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Graphene oxide ternary nanohybrids co-functionalized by phenyl porphyrins and thieyl-appended porphyrins for efficient optical limiting
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Graphene oxide ternary nanohybrids co-functionalized by phenyl porphyrins and thieyl-appended porphyrins for efficient optical limiting Xiaodong Chen a, Yun Wang b, Lilan Zhou b, Aijian Wang a, *, Chi Zhang a, ** a b
School of Chemistry & Chemical Engineering, Jiangsu University, Zhenjiang, 212013, PR China Jingjiang College, Jiangsu University, Zhenjiang, 212013, PR China
A R T I C L E I N F O
A B S T R A C T
Keywords: Graphene oxide Porphyrins Ternary nanohybrid Charge transfer Optical limiting
The combination of graphene oxide and different porphyrins is attracted much attention as optical limiting systems. In this article, three novel porphyrins covalently functionalized GO nanohybrids (TPP-GO, TTP-GO and TPP-GO-TTP) have been designed and synthesized by covalent functionalization approach. The formation of these nanohybrids has been confirmed by various spectroscopic techniques including Fourier transform infrared spectroscopy, Raman, scanning electron microscope images, X-ray photoelectron spectroscopy and thermogra vimetric analysis. Raman spectra and photophysical studies demonstrated effective charge transfer effect from the porphyrins to the GO. The as-prepared nanohybrids exhibited superior nonlinear absorption and optical limiting performances exciting by the 4 ns laser pulses, significantly better than their components due to more effective charge transfer effect. Particularly, the TPP-GO-TTP ternary nanohybrid showed the best nonlinear optical and optical limiting properties in comparison with those of other both binary nanohybrids, highlighting the influence of the introduction of different porphyrins on the photophysical and optical limiting performances of the as-prepared nanohybrids.
1. Introduction In recent years, optical limiting materials have been the focus of considerable research interest due to they can protect the human eyes and sensitive optical sensors from intense laser radiations [1,2]. An ideal optical limiting system (optical limiter) can exhibit high linear trans mittance for low intensity of input laser pulses up to a clamping threshold, and then the optical limiting system starts to attenuate the incident radiation when the incident laser fluence is above the clamping threshold [3].A desirable nonlinear optical material in optical limiter requires high linear transmittance, good optical quality, low optical limiting threshold, and large nonlinear optical response et al. [4,5]The main mechanisms for optical limiting are nonlinear absorption (exci ted-state absorption, reverse saturable absorption, free-carrier absorp tion and two-photon absorption), nonlinear refraction and nonlinear scattering depending on the material and laser pulse [2,6].Despite their importance, the capability of the existing optical limiters is still far from ideal. Indeed, for practical applications, no single optical limiting ma terial or mechanism can meet the stringent application requirements. Therefore, exploring novel systems with efficient nonlinear optical
performances suitable for use in harsh environments is a noteworthy attempt for the development of practical optical limiters for the laser protection applications. Many research during the past several years has focused on the porphyrin/phthalocyanine functionalized graphene binary nanohybrids for optical limiting applications [7–11]. However, to the best of our knowledge, the possibility of instantaneous introduction of two different porphyrins onto the graphene nanosheets to form ternary nanohybrids for optical limiting has not been attempted, even though this design strategy may provide new insight into the development of multifunc tional optical limiting materials with versatile properties. Accordingly, we became interested in combining two kinds of porphyrins and gra phene oxide in a single system and exploring their optical limiting performances. In this study, we report that the design of graphene oxide ternary nanohybrids co-functionalized by phenyl porphyrins and thieyl-appended porphyrins is an effective way to prepare efficient op tical limiting materials.
* Corresponding author. ** Corresponding author. E-mail addresses: [email protected] (A. Wang), [email protected] (C. Zhang). https://doi.org/10.1016/j.dyepig.2019.108057 Received 29 July 2019; Received in revised form 14 October 2019; Accepted 17 November 2019 Available online 18 November 2019 0143-7208/© 2019 Elsevier Ltd. All rights reserved.
Please cite this article as: Xiaodong Chen, Dyes and Pigments, https://doi.org/10.1016/j.dyepig.2019.108057
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2. Experimental section
2.4. Preparation of TTP covalently functionalized GO (TTP-GO)
2.1. Materials and reagents
In a typical reaction, the GO-(CO)Cl (80 mg) and TTP (26.7 mg) was added to a mixture of DMF (anhydrous, 15 mL) and Et3N (anhydrous, 0.5 mL), and the mixture was sonicated at 150 W power for 30 min to form a homogeneous solution. The reaction mixture was heated at 90 � C for 5 days under N2.The resulting solution was cooled to room temper ature after removing the heat source. The ice water (150 mL) was added to the obtained solution to settle down the product. The black precipi tate was filtered by using a 0.45 μm single layer nylon film, and washed with CH3OH, dichloromethane, deionized water, and EtOH to remove unreacted precursors and other contaminants, after which the filtrate was colorless. The final nanohybrid was dried under vacuum for 24 h and labeled as TTP-GO (Scheme 1).
The dimethylformamide (DMF), pyrrole and triethylamine (Et3N) were dried over CaH2and distilled before use. All other reagents and chemicals obtained from Shanghai Sinopharm Chemical Reagent Co. Ltd. were of chemical and analytical grade, and were used as received unless otherwise noted. Graphene oxide (GO), acyl chlorinated GO (GO(CO)Cl), monohydroxyporphyrin (TPP) and thieyl-appended porphyrin (TTP) were prepared based on the previous reported synthetic methods [12–14]. 2.2. Characterization methods
2.5. Preparation of TPP grafted GO (TPP-GO)
The Fourier transform infrared (FTIR) spectra using spectroscopic grade KBr pellets were carried out on a MB154S-FTIR spectrometer (Canada).Raman spectra were obtained on a RenishawInvia Raman Microscope at room temperature upon excitation by the Arion laser source at 532 nm. X-ray photoelectron spectroscopy (XPS) was taken from a PHI–5000C ESCA (PerkinElmer) spectrometer by using a monochromatic Al Kα (1486.6 eV) X-ray source. The scanning electron microscopy (SEM) images were measured on a HitachiS4800electron microscope at accelerating voltage of 5.0 kV. Thet hermogravimetric analysis (TGA) was carried out on a PerkinElmer 1 system in a flowing nitrogen gas atmosphere with a heating rate of 10 � C/min.
Initially, the TPP (26 mg) was dissolved in a mixture of DMF (anhydrous, 15 mL) and Et3N (anhydrous, 0.5 mL). Thereafter, the GO (80 mg) was added to above solution and then was stirred at 90 � C for 5 days (Scheme 2).After the reaction, the handing procedures were as above for the TTP-GO nanohybrid. 2.6. Preparation of ternary nanohybrid (TPP-GO-TTP) The graphene oxide ternary nanohybrids co-functionalized by phenyl porphyrins and thieyl-appended porphyrins (TPP-GO-TPP) was prepared following a similar synthetic procedure to those for TTP-GO and TPP-GO. Briefly, GO (80 mg) was added to a solution of TPP (13 mg) and TTP (13.4 mg) in a mixture of DMF (anhydrous, 15 mL) and Et3N (anhydrous, 0.5 mL) under a N2 atmosphere. The resulting solution was stirred at 90 � C for 5 days (Scheme 3). The handing procedures were as above for the TTP-PPy nanohybrid.
2.3. Photophysical and nonlinear optical measurements The ultraviolet–visible (UV–Vis) absorption and fluorescence spectra were carried out to investigate the photophysical properties of the asprepared samples, which were recorded by using a Shimadzu UV-2450 spectrophotometer and a QuantaMaster™ 40Spectrofluorometer (Photon Technology International, Inc), respectively. The Z-scan tech nique with a Nd:YAG laser (Continuum, Surelite II) at 532 nm pulse of 4 ns was used to investigate the nonlinear optical performances (including nonlinear absorption and optical limiting) of the samples at a repetition rate of 2 Hz. The laser beam energy employed is 12 μJ. The samples uniformly dissolved in DMSO by ultrasonic treatment were positioned in 1 mm length of quartz cuvette for the measurement. For comparison purposes, all samples in DMSO were adjusted to have the same linear transmittance of 75%. The detailed informations about the laser system and experimental procedures were given by previous reported litera tures [6,10,11].
3. Results and discussion 3.1. Structure, composition and morphology The FTIR and Raman spectra provide some information about the formation of the as-prepared nanohybrids. Fig. 1 shows the FTIR spectra of GO, TPP, TTP, TPP-GO, TTP-GO and TPP-GO-TTP. For GO, the peaks observed at 1378 (νC-OH), 1623 (νC¼C), 1731 (νC¼O), and 3405 (νO-H) cm 1 correspond the characteristic peaks of the C–OH, aromatic C¼C bond, carboxyland hydroxyl groups present in GO, respectively, which are consistent with previous reports [15]. In the case of the as-prepared
Scheme 1. Synthetic routes of TTP-GO. 2
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Scheme 2. Synthetic routes of TPP-GO.
Scheme 3. Synthetic routes of TPP-GO-TTP.
order scattering of E2g phonons from sp2 carbon atoms, respectively [17].The Raman spectrum of TPP-GO exhibits two peaks at around 1341.13 and 1596.65 cm 1, respectively, while the D- and G-bands of TTP-GO were also blue-shifted, being found at around 1344.98 and 1587.97 cm 1, respectively. After the introduction of TPP and TTP, the D- and G-bands of TPP-GO-TTP are observed at 1332.19 and 1582.89 cm 1, respectively. It should be noted that the G-band of GO shifts to lower frequency after the introduction of one electron donor compo nent, and consistent with the charge transfer from the donor component to the GO [18]. In contrast, when an electron acceptor component is introduced, the G-band shifts to higher frequency, implying the occur rence of charge transfer from the GO to the dopant component. It is thus that above results indicate that there is interfacial interactions between porphyrins and GO, which is favorable for the charge transfer from the porphyrins to the GO. Particularly, the TPP-GO-TTP exhibits the largest
nanohybrids, some characteristic peaks observed in the spectra of GO and porphyrins can be found, confirming the porphyrins have been grafted onto the GO sheets. The disappearance of the peak observed at 1378 cm 1 further implied that the porphyrins have been covalently bonded to the GO via the carboxylic acid linkage [16].In the case of the TPP-GO-TTP nanohybrid, the peak at 1731 cm 1 corresponding to the carboxyl group disappeared, and a new peak at 1710 cm 1was observed, which can be assigned to the formation of the ester bond. Similar results were also observed for TPP-GO and TTP-GO. The absence of the peak at 1623 cm 1 suggest that the introduction of porhyrins influences the aromatic system in GO, which was confirmed by the Raman spectra (Fig. 2). The Raman spectrum of GO exhibits two characteristic peaks, i.e. the D band at 1348.84 cm 1 and G band at 1599.54 cm 1, corresponding to the breathing mode of k-point phonons of A1g symmetry and the first3
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down-shift of the G band when compared to those of TPP-GO and TTP-GO, consistent with more effective charge transfer effect. Of particular note is the intensity ratio of D/G bands (ID/IG) provides a measure of the local defects and disorder in graphene. The ID/IG ratio of TPP-GO-TTP (1.066) is larger than those of GO (0.979), TPP-GO (1.048) and TTP-GO (1.035), which can be ascribed to the presence of more defects resulting from the strong interactions between porphyrins and GO. These changes indicate that the porphyrins have been covalently linked to the GO sheets, and the defective degree of TPP-GO-TTP is at high level, which is higher than those of TPP-GO and TTP-GO. Raman technique is sensitive to the electronic structure of the materials, so above results are consistent with the chemical functionalization. The formation of the as-prepared nanohybrids was further confirmed by the SEM images (Fig. 3). The GO has a sheet-like morphology with some wrinkled texture (Fig. 3a). The surface of TPP-GO (Fig. 3b), TTP-GO (Fig. 3c) and TPP-GO-TTP (Fig. 3d) are much rougher than that of GO due to the covalent grafting of porphyrins onto the GO nanosheet. Particularly, the TPP-GO-TTP has a dense surface, composed of plate-like particles with scrolled edges. The covalent attachment of porphyrins onto GO nanosheets was further confirmed by the XPS spectra. Fig. 4 displays the survey spectra of the as-prepared samples. It can be seen that only two peaks corre sponding to C and O elements were detected in the spectrum of GO. After the introduction of porphyrins, one additional peak can be observed for TPP-GO that originated from the N 1s. In the case of TTP-GO and TPPGO-TTP, two additional elements N and S can be detected, suggesting the successful grafting of porphyrins onto the GO surface. Fig. 5 shows the high-resolution XPS spectra of N 1s and S 2p for the as-prepared samples. As shown in Fig. 5a, the N 1s peak of TPP-GO is centered at 399.80 eV. In contrast, the bonding energies of N 1s for TTP-GO and TPP-GO-TTP are shifted to 399.97 and 399.73 eV. The S 2p peak of TTPGO appears at 163.88 eV. However, there is an obvious blue-shift for the S 2p peak of TPP-GO-TTP (163.88–163.67 eV) when compared to TTPGO. Both N 1s and S 2p spectra present the direct evidence of successful fabrication of porphyrins functionalized GO. The loading content of porphyrin molecules covalently grafted onto
Fig. 1. FTIR spectra of the as-prepared samples.
Fig. 2. Raman spectra of the as-prepared samples.
Fig. 3. SEM images of (a) GO, (b) TPP-GO, (c) TTP-GO, and (d) TPP-GO-TTP. 4
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corresponding to the TPP moieties is shifted from 421 to 424 nm, whereas this typical Soret absorption became even weaker and broader. Similarly, when compared to the TTP solution, the typical peak of TTP-GO gets broadened and red-shifted (428–430 nm), and the intensity is diminished. The TPP-GO-TTP nanohybrid exhibits a suppressed Soret band at around 423 nm, corresponding to a red-shift of 2 nm and a blue-shift of 5 nm compared to that of TPP and TTP, respectively. These results are consistent with the grafting of different porphyrins to GO modifying the ground state spectral performance. It should be noted that the peak shifts for the as-prepared nanohybrids are relatively small, which may be due to the fact that the para position as in the present work typically has a weaker effect [22]. As known, the occurrence of charge transfer between porphyrins and GO could be verified by the fluorescence spectra, where it has been demonstrated that the fluorescence intensity of porphyrins would decrease when they are hybridized with an electron acceptor component [23]. As shown in Fig. 7b, TPP and TTP exhibit typical porphyrin fluo rescence emission performance by exciting at the same wavelength and at constant absorption, while no fluorescence signal was observed for GO. Compared to TPP, the TPP-GO fluorescence intensity is quenched by 68%, implying the occurrence of excited-state events, i.e. energy transfer and/or electron transfer [24]. The fluorescence spectrum of TTP-GO has the similar profile as that of TTP, but its fluorescence emission quantum yield is only approximate 38% of that of TTP. It is thus that the magnitude of fluorescence quenching ofTPP-GO is larger than that of TTP-GO. Interestingly, the fluorescence intensity of TPP-GO-TTP is larger than those of TTP and TTP-GO due to the presence of TPP. However, compared to TPP-GO, the larger fluorescence quenching can be observed for TPP-GO-TTP (83%) in comparison with that of TPP, stemming from the introduction of TTP in TPP-GO-TTP. In other words, the strongest fluorescence degree was observed for TPP-GO-TTP in comparison with those of TPP-GO and TTP-GO.
Fig. 4. XPS spectra of GO, TPP-GO, TTP-GO, andTPP-GO-TTP.
the GO nanosheets for the as-prepared nanohybrids was determined by the TGA analysis [19].As shown in Fig. 6, the weight loss of GO at 800 � C is about 44.1%. In contrast, the TGA curves of TPP-GO, TTP-GO, and TPP-GO-TTPexhibited about 67.4%, 61.2% and64.6% weight loss, respectively. Therefore, the amount of porphyrins linked to GO can be determined to be about 23.3% (TPP), 17.1% (TTP) and 20.5% (TPP þ TTP) for TPP-GO, TTP-GO, and TPP-GO-TTP, respectively. Moreover, it is clear that the weight loss of the as-prepared nanohybrids is much larger than that of GO in the range of 30–800 � C, which can be ascribed to the thermolysis of porphyrin molecules covalently linked onto the GO nanosheets. In addition, the loading content of TPP and TTP function alized on the GO nanohybrids is determined to be about 26.3% and 18.2% using molar extinction coefficient (Figs. S1 and S2), which are consistent with the results of TGA. However, due to the presence of two types of porphyrins (TPP and TTP), it may be difficult to calculate the content of TPP and TTP on the TPP-GO-TTP using molar extinction coefficient. 3.2. Photophysical properties The UV–vis absorption spectra were recorded as a probe for exploring the electronic configuration of the as-prepared samples. As shown in Fig. 7a, the spectrum of GO is a typically featureless curve, while the three nanohybrids have an obvious Soret absorption band, which is possibly due to the introduced porphyrin molecules [20]. Obviously, the UV–vis absorption spectra of the as-prepared nano hybrids present a composite curve including GO and porphyrins, and the characteristic absorption peaks of porphyrins and GO were influenced by the porphyrins covalent grafted onto the GO nanosheets. The TPP has a sharp and intense Soret band at around 421 nm and four Q-bands in the range of 500–700 nm, which arethe characteristic peak of porphyrin [21]. After covalently linked with GO, the Soret band of TPP-GO
Fig. 6. TGA curves of GO, TPP-GO, TTP-GO, and TPP-GO-TTP.
Fig. 5. The amplified N 1s (a) and S 2p (b) XPS spectra of the as-prepared samples. 5
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Fig. 7. (a) UV–vis absorption and (b) steady state fluorescence spectra of the as-prepared samples.
Consistent with the results of Raman spectra, the fluorescence quench ing further confirms the efficient charge transfer effect between por phyrins (electron donor) and GO (electron acceptor), resulting in the enhanced optoelectronic performances.
TPP-GO was superior to that of TTP-GO, but inferior to that of TTP-GO-TPP. The TTP-GO-TPP has the largest dip in the transmittance of all samples, implying that it should have the best optical limiting [29]. This observation clearly suggested that the introduction of different porphyrins onto the GO nanosheets exert a crucial effect on the nonlinear absorption performances of the resultant nanohybrids. The TTP-GO-TPP exhibited better nonlinear absorption property than those of multiwalled carbon nanotubes and reduced graphene oxide cova lently functionalized by axially coordinated metal-porphyrins [10,11], but further comment is not warranted due to the different experimental geometry. Fig. 9 displays the optical limiting performances of the as-prepared samples. For the purpose of comparison, the GO was used as a stan dard. It can be clearly seen that the TPP-GO-TTP present much better optical limiting property than those of TPP-GO and TTP-GO at the same linear transmittance, consistent with the open-aperture Z-scan results. The limiting thresholds of TPP-GO, TTP-GO and TPP-GO-TTP are determined to be 1.65, 1.16 and 1.08 J/cm2, respectively. These values are considerably better than those of GO (>3.0 J/cm2) [12], C60 (2.2 J/cm2) [12] and single-wallled carbon nanotubes (2.5 J/cm2) [30], though different experimental conditions should be cautioned. The limiting thresholds and optical limiting properties of TPP and TTP were not presented in the present case, due to the normalized transmittance did not drop below 50% of the linear transmittance. Considering the donor-acceptor motif of TPP-GO, TTP-GO and TPP-GO-TTP nanohybrids in the excited-state, the increased optical limiting can be ascribed to the charge-separated excited state generated by the photoinduced electron transfer from the electron donor porphyrins to the electron acceptor GO. Indeed, the more effective charge transfer effect of TPP-GO-TTP has been confirmed by fluorescence and Raman spectra, and thus the TPP-GO-TTP exhibited the best optical limiting effect. Comparatively, the enhancement of optical limiting response of TTP-GO is the smallest among the as-prepared three nanohybrids, due to the low charge transfer efficiency. Based on above results, it is clear that the attachment of porphyrins onto the GO nanosheets obviously improved the nonlinear optical and optical limiting performances of these porphyrins-GO functionalized materials. The enhanced optical limiting performances render these nanohybrids suitable for potential applications as optical limiters in ns regime. The optoelectronic performances of GO can be tuned by the chemical functionalization (indeed the introduction of different por phyrins), so one can expect such chemical modification to result in the control and tailoring of the optical limiting performances of GO. This may also enable the generation of GO-based optical limiters, which could be comparable to, if not better than, the traditional optical devices.
3.3. Nonlinear optical performances In recent years, nonlinear optical performances of graphene have been investigated widely because of their excellent optical limiting and broadband applicability [25]. Porphyrins functionalized GO has been reported to be good optical limiting system with a combination of mechanisms [1–3]. Nevertheless, the nonlinear optical properties have hardly been investigated for functionalized GO with two different por phyrins. So it is very interesting to study the nonlinear optical (including optical limiting) performances of the nanohybrid system of GO with phenyl porphyrins and thieyl-appended porphyrins. The nonlinear optical performances of the as-prepared samples were investigated by the open-aperture Z-scan technique. The experimental process is similar to that in the literature [26]. For comparison, all samples were adjusted to have the same linear transmittance of 75% at 532 nm. As shown in Fig. 8, all samples exhibited a reduction on the focal point of the lens upon excitation at 532 nm with 4 ns pulses, indicating a decreasing transmittance for reverse saturable absorption, and consistent with the occurrence of optical limiting [27,28]. No obvious nonlinear optical signal was observed for the solvent DMSO under the same experimental process, so the observed nonlinear ab sorption effect must result from the solutes. At the focal point, the normalized transmittances of GO, TPP, TPP-GO, TTP, TTP-GO and TTP-GO-TPP decrease to be 52%, 75%, 29%, 84%, 36% and 17% of the input fluence, respectively (Fig. 8). Obviously, the nonlinear optical performances of TPP-GO, TTP-GO and TTP-GO-TPP are better than those of their components. The nonlinear absorption performance of
4. Conclusions In summary, three novel porphyrins covalently functionalized GO
Fig. 8. The open-aperture Z-scan curves of the as-prepared samples. 6
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Fig. 9. Comparison of optical limiting performance of (a) GO, (b) TTP-GO, (c) TPP-GO and TPP-GO-TTP.
nanohybrids (TPP-GO, TTP-GO and TPP-GO-TTP) have been designed and synthesized, and are characterized by various spectroscopic tech niques including FTIR, Raman, SEM, XPS and TGA spectra. Raman spectra and photophysical studies demonstrated effective charge trans fer effect from the porphyrins to the GO. The nonlinear optical and optical limiting performances were investigated by using the Z-scan technique at 532 nm under nanosecond regime. The as-prepared nano hybrids exhibited superior nonlinear absorption and optical limiting performances exciting by the 4 ns laser pulses, significantly better than their components. The enhanced nonlinear optical performances were ascribed to the effective charge transfer effect between porphyrins and GO. Particularly, the TPP-GO-TTP ternary nanohybrid showed the best nonlinear optical and optical limiting properties in comparison with those of other both binary nanohybrids, due to more effective charge transfer effect. The type of porphyrins was found to be an important factor influencing the optical nonlinearities of the porphyrins-GO nanohybrids. These results indicate that the combination GO with different porphyrins is a promising approach to design and prepare practical optical limiting devices.
References [1] Chen Y, Bai T, Dong NN, Fan F, Zhang SF, Zhuang XD, Sun J, Zhang B, Zhang XY, Wang J, Blau WJ. Graphene and its derivatives for laser protection. Prog Mater Sci 2016;84:118–57. [2] Wang AJ, Ye J, Humphrey MG, Zhang C. Graphene and carbon-nanotube nanohybrids covalently functionalized by porphyrins and phthalocyanines for optoelectronic properties. Adv Mater 2018;30:1705704. [3] Dissanayake DMAS, Cifuentes MP, Humphrey MG. Optical limiting properties of (reduced) graphene oxide covalently functionalized by coordination complexes. Coord Chem Rev 2018;375:489–513. [4] Liang GW, Tsang YH, Zeng LH, Liu X, Li J, Qu JL, Wen Q. Optical limiting properties of a few-layer MoS2/PMMA composite under excitation of ultrafast pulses. J Mater Chem C 2019;7:495–502. [5] Harris J, Gai LZ, Kubheka G, Mack J, Nyokong T, Shen Z. Optical limiting properties of 3,5-dithienylenevinylene BODIPY dyes at 532 nm. Chem Eur J 2017; 23:14507–14. [6] Wang AJ, Long LL, Meng SC, Li XF, Zhao W, Song YL, Cifuentes MP, Humphrey MG, Zhang C. Cooperative enhancement of optical nonlinearities in a porphyrin derivative bearing a pyrimidine chromophore at the periphery. Org Biomol Chem 2013;11:4250–7. [7] Zhu JH, Li YX, Chen Y, Wang J, Zhang B, Zhang JJ, Blau WJ. Graphene oxide covalently functionalized with zinc phthalocyanine for broadband optical limiting. Carbon 2011;49:1900–5. [8] Song WN, He CY, Zhang W, Gao YC, Yang YX, Wu YQ, Chen ZM, Li XC, Dong YL. Synthesis and nonlinear optical properties of reduced graphene oxide hybrid material covalently functionalized with zinc phthalocyanine. Carbon 2014;77: 1020–30. [9] Xu YF, Liu ZB, Zhang XL, Wang Y, Tian JG, Huang Y, Ma YF, Zhang XY, Chen YS. A graphene hybrid material covalently functionalized with porphyrin: synthesis and optical limiting property. Adv Mater 2009;21:1275–9. [10] Wang AJ, Song JB, Jia D, Yu W, Long LL, Song YL, Cifuentes MP, Humphrey MG, Zhang L, Shao JD, Zhang C. Functionalization of reduced graphene oxide with axially-coordinated metal-porphyrins: facile syntheses and temporally-dependent nonlinear optical properties. Inorg Chem Front 2016;3:296–305. [11] Wang AJ, Song JB, Huang ZP, Song YL, Yu W, Dong HL, Hu WP, Cifuentes MP, Humphrey MG, Zhang L, Shao JD, Zhang C. Mult-iwalled carbon nanotubes covalently functionalized by axially coordinated metal-porphyrins: facile syntheses and temporally dependent optical performance. Nano Res 2016;9:458–72. [12] Liu R, Hu JY, Zhu SQ, Lu JP, Zhu HJ. Synergistically enhanced optical limiting property of graphene oxide hybrid materials functionalized with Pt complexes. ACS Appl Mater Interfaces 2017;9:33029–40. [13] Wang AJ, Fang Y, Yu W, Long LL, Song YL, Zhao W, Cifuentes MP, Humphrey MG, Zhang C. Allyloxyporphyrin-functionalized multiwalled carbon nanotubes: synthesis by radical polymerization and enhanced optical-limiting properties. Chem Asian J 2014;9. 639-548. [14] Inoue M, Kim KS, Suzuki M, Lim JM, Shin JY, Kim D, Osuka A. Thermal fusion reactions of meso-(3-thienyl) groups in [26]hexaphyrins to produce Mobius aromatic molecules. Angew Chem Int Ed 2009;48:6687–90.
Declaration of competing interest The authors declare no conflict of interest. Acknowledgements This work was supported by the National Natural Science Foundation of China (51432006 and 51172100), the Ministry of Education of China for the Changjiang Innovation Research Team (IRT13R24), the Ministry of Education and the State Administration of Foreign Experts Affairs of China for the 111 Project (B13025), and the China Postdoctoral Foun dation (2016M601733, 2018T110446) and the Innovation Program of Shanghai Municipal Education Commission. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi. org/10.1016/j.dyepig.2019.108057. 7
X. Chen et al.
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[15] Krishan MBM, Venkatramaiah N, Venkatesan R, Rao DN. Synthesis and structural, spectroscopic and nonlinear optical measurements of graphene oxide and its composites with metal and metal free porphyrins. J Mater Chem 2012;22:3059–68. [16] Liu ZB, Xu YF, Zhang XY, Zhang XL, Chen YS, Tian JG. Porphyrin and fullerene covalently functionalized graphene hybrid materials with large nonlinear optical properties. J Phys Chem B 2009;113:9681–6. [17] Wang AJ, Yu W, Fang Y, Song YL, Jia D, Long LL, Cifuentes MP, Humphrey MG, Zhang C. Facile hydrothermal synthesis and optical limiting properties of TiO2reduced graphene oxide nanocomposites. Carbon 2015;89:130–41. [18] Ouyang QY, Xu Z, Lei ZY, Dong HW, Yu HL, Qi LH, Li CY, Chen YJ. Enhanced nonlinear optical and optical limiting properties of graphene/ZnO hybrid organic glasses. Carbon 2014;67:214–20. [19] Song WN, He CY, Dong YL, Zhang W, Gao YC, Wu YQ, Chen ZM. The effects of central metals on the photophysical and nonlinear optical properties of reduced graphene oxide-metal (II) phthalocyanine hybrids. Phys Chem Chem Phys 2015;17: 7149–57. [20] X. Y. Zhang, L. L. Hou, A. Cnossen, A. C. Coleman, O. Ivashenko, P. Rudolf, B. J. van Wees, W. R. Browne, B. L. Feringa, One-pot functionalization of graphene with porphyrin through cycloaddition reactions, Chem Eur J, 1017, 17, 8957-8964. [21] Wu L, Wang JS, Feng LY, Ren JS, Wei WL, Ou XG. Lable-free ultrasensitive detection of human telomerase activity using porphyrin-functionalized graphene and electrochemiluminescence techniaue. Adv Mater 2012;24:2447–52. [22] Wang AJ, Yu W, Huang ZP, Zhou F, Song JB, Song YL, Long LL, Cifuentes MP, Humphrey MG, Zhang L, Shao JD, Zhang C. Covalent functionalization of reduced
[23] [24] [25] [26] [27] [28] [29]
[30]
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graphene oxide with porphyrin by means of diazonium chemistry for nonlinear optical performance. Sci Rep 2016;6:23325. Du YL, Zhu K, Fang Y, Zhang SL, Zhang XR, Lu YN, Yang YC, Song YL, Wang GB. Poly(arylene ether ketone)s with pendant porphyrins: synthesis and investigation on optical limiting properties. RSC Adv 2015;5:48311–22. Karousis N, Economopoulos SP, Sarantopoulou E, Tagmatarchis N. Porphyrin counter anion in imidazolium-modified graphene-oxide. Carbon 2010;48:854–60. Wang J, Hernandez Y, Lotya M, Coleman JN, Blau WJ. Broadband nonlinear optical response of graphene dispersions. Adv Mater 2009;21:2430–5. Wang AJ, Zhao W, Yu W. Effect of acid/base on the third-order optical nonlinearity of polypyrrole. J Mol Struct 2015;1099:291–6. Zhao W, Wang Y, Wang AJ, Qian J, Zhu WH, Dou SP, Wang Q, Zhong Q, Chen QH. Novel Bi2O2CO3/polypyrrole/g-C3N4 nanocomposites with efficient photocatalytic and nonlinear optical properties. RSC Adv 2017;7:7658–70. Zhao W, Li C, Wang AJ, Lv CC, Zhu WH, Dou SP, Wang Q, Zhong Q. Polyaniline decorated Bi2MoO6 nanosheets with effective interfacial charge transfer as photocatalysts and optical limiters. Phys Chem Chem Phys 2017;19:28696–709. Zhao W, Wang AJ, Wang Y, Lv CC, Zhu WH, Dou SP, Wang Q, Zhong Q. Accessible fabrication and mechanism insight of heterostructured BiOCl/Bi2MoO6/g-C3N4 nanocomposites with efficient photosensitized activity. J Alloy Comp 2017;726: 164–72. Liu ZB, Tian JG, Guo Z, Ren DM, Du F, Zheng JY, Chen YS. Enhanced optical limiting effects in porphyrin-covalently functionalized single-walled carbon nanotubes. Adv Mater 2008;20:511–5.
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Dyes and Pigments journal homepage: http://www.elsevier.com/locate/dyepig
Graphene oxide ternary nanohybrids co-functionalized by phenyl porphyrins and thieyl-appended porphyrins for efficient optical limiting Xiaodong Chen a, Yun Wang b, Lilan Zhou b, Aijian Wang a, *, Chi Zhang a, ** a b
School of Chemistry & Chemical Engineering, Jiangsu University, Zhenjiang, 212013, PR China Jingjiang College, Jiangsu University, Zhenjiang, 212013, PR China
A R T I C L E I N F O
A B S T R A C T
Keywords: Graphene oxide Porphyrins Ternary nanohybrid Charge transfer Optical limiting
The combination of graphene oxide and different porphyrins is attracted much attention as optical limiting systems. In this article, three novel porphyrins covalently functionalized GO nanohybrids (TPP-GO, TTP-GO and TPP-GO-TTP) have been designed and synthesized by covalent functionalization approach. The formation of these nanohybrids has been confirmed by various spectroscopic techniques including Fourier transform infrared spectroscopy, Raman, scanning electron microscope images, X-ray photoelectron spectroscopy and thermogra vimetric analysis. Raman spectra and photophysical studies demonstrated effective charge transfer effect from the porphyrins to the GO. The as-prepared nanohybrids exhibited superior nonlinear absorption and optical limiting performances exciting by the 4 ns laser pulses, significantly better than their components due to more effective charge transfer effect. Particularly, the TPP-GO-TTP ternary nanohybrid showed the best nonlinear optical and optical limiting properties in comparison with those of other both binary nanohybrids, highlighting the influence of the introduction of different porphyrins on the photophysical and optical limiting performances of the as-prepared nanohybrids.
1. Introduction In recent years, optical limiting materials have been the focus of considerable research interest due to they can protect the human eyes and sensitive optical sensors from intense laser radiations [1,2]. An ideal optical limiting system (optical limiter) can exhibit high linear trans mittance for low intensity of input laser pulses up to a clamping threshold, and then the optical limiting system starts to attenuate the incident radiation when the incident laser fluence is above the clamping threshold [3].A desirable nonlinear optical material in optical limiter requires high linear transmittance, good optical quality, low optical limiting threshold, and large nonlinear optical response et al. [4,5]The main mechanisms for optical limiting are nonlinear absorption (exci ted-state absorption, reverse saturable absorption, free-carrier absorp tion and two-photon absorption), nonlinear refraction and nonlinear scattering depending on the material and laser pulse [2,6].Despite their importance, the capability of the existing optical limiters is still far from ideal. Indeed, for practical applications, no single optical limiting ma terial or mechanism can meet the stringent application requirements. Therefore, exploring novel systems with efficient nonlinear optical
performances suitable for use in harsh environments is a noteworthy attempt for the development of practical optical limiters for the laser protection applications. Many research during the past several years has focused on the porphyrin/phthalocyanine functionalized graphene binary nanohybrids for optical limiting applications [7–11]. However, to the best of our knowledge, the possibility of instantaneous introduction of two different porphyrins onto the graphene nanosheets to form ternary nanohybrids for optical limiting has not been attempted, even though this design strategy may provide new insight into the development of multifunc tional optical limiting materials with versatile properties. Accordingly, we became interested in combining two kinds of porphyrins and gra phene oxide in a single system and exploring their optical limiting performances. In this study, we report that the design of graphene oxide ternary nanohybrids co-functionalized by phenyl porphyrins and thieyl-appended porphyrins is an effective way to prepare efficient op tical limiting materials.
* Corresponding author. ** Corresponding author. E-mail addresses: [email protected] (A. Wang), [email protected] (C. Zhang). https://doi.org/10.1016/j.dyepig.2019.108057 Received 29 July 2019; Received in revised form 14 October 2019; Accepted 17 November 2019 Available online 18 November 2019 0143-7208/© 2019 Elsevier Ltd. All rights reserved.
Please cite this article as: Xiaodong Chen, Dyes and Pigments, https://doi.org/10.1016/j.dyepig.2019.108057
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2. Experimental section
2.4. Preparation of TTP covalently functionalized GO (TTP-GO)
2.1. Materials and reagents
In a typical reaction, the GO-(CO)Cl (80 mg) and TTP (26.7 mg) was added to a mixture of DMF (anhydrous, 15 mL) and Et3N (anhydrous, 0.5 mL), and the mixture was sonicated at 150 W power for 30 min to form a homogeneous solution. The reaction mixture was heated at 90 � C for 5 days under N2.The resulting solution was cooled to room temper ature after removing the heat source. The ice water (150 mL) was added to the obtained solution to settle down the product. The black precipi tate was filtered by using a 0.45 μm single layer nylon film, and washed with CH3OH, dichloromethane, deionized water, and EtOH to remove unreacted precursors and other contaminants, after which the filtrate was colorless. The final nanohybrid was dried under vacuum for 24 h and labeled as TTP-GO (Scheme 1).
The dimethylformamide (DMF), pyrrole and triethylamine (Et3N) were dried over CaH2and distilled before use. All other reagents and chemicals obtained from Shanghai Sinopharm Chemical Reagent Co. Ltd. were of chemical and analytical grade, and were used as received unless otherwise noted. Graphene oxide (GO), acyl chlorinated GO (GO(CO)Cl), monohydroxyporphyrin (TPP) and thieyl-appended porphyrin (TTP) were prepared based on the previous reported synthetic methods [12–14]. 2.2. Characterization methods
2.5. Preparation of TPP grafted GO (TPP-GO)
The Fourier transform infrared (FTIR) spectra using spectroscopic grade KBr pellets were carried out on a MB154S-FTIR spectrometer (Canada).Raman spectra were obtained on a RenishawInvia Raman Microscope at room temperature upon excitation by the Arion laser source at 532 nm. X-ray photoelectron spectroscopy (XPS) was taken from a PHI–5000C ESCA (PerkinElmer) spectrometer by using a monochromatic Al Kα (1486.6 eV) X-ray source. The scanning electron microscopy (SEM) images were measured on a HitachiS4800electron microscope at accelerating voltage of 5.0 kV. Thet hermogravimetric analysis (TGA) was carried out on a PerkinElmer 1 system in a flowing nitrogen gas atmosphere with a heating rate of 10 � C/min.
Initially, the TPP (26 mg) was dissolved in a mixture of DMF (anhydrous, 15 mL) and Et3N (anhydrous, 0.5 mL). Thereafter, the GO (80 mg) was added to above solution and then was stirred at 90 � C for 5 days (Scheme 2).After the reaction, the handing procedures were as above for the TTP-GO nanohybrid. 2.6. Preparation of ternary nanohybrid (TPP-GO-TTP) The graphene oxide ternary nanohybrids co-functionalized by phenyl porphyrins and thieyl-appended porphyrins (TPP-GO-TPP) was prepared following a similar synthetic procedure to those for TTP-GO and TPP-GO. Briefly, GO (80 mg) was added to a solution of TPP (13 mg) and TTP (13.4 mg) in a mixture of DMF (anhydrous, 15 mL) and Et3N (anhydrous, 0.5 mL) under a N2 atmosphere. The resulting solution was stirred at 90 � C for 5 days (Scheme 3). The handing procedures were as above for the TTP-PPy nanohybrid.
2.3. Photophysical and nonlinear optical measurements The ultraviolet–visible (UV–Vis) absorption and fluorescence spectra were carried out to investigate the photophysical properties of the asprepared samples, which were recorded by using a Shimadzu UV-2450 spectrophotometer and a QuantaMaster™ 40Spectrofluorometer (Photon Technology International, Inc), respectively. The Z-scan tech nique with a Nd:YAG laser (Continuum, Surelite II) at 532 nm pulse of 4 ns was used to investigate the nonlinear optical performances (including nonlinear absorption and optical limiting) of the samples at a repetition rate of 2 Hz. The laser beam energy employed is 12 μJ. The samples uniformly dissolved in DMSO by ultrasonic treatment were positioned in 1 mm length of quartz cuvette for the measurement. For comparison purposes, all samples in DMSO were adjusted to have the same linear transmittance of 75%. The detailed informations about the laser system and experimental procedures were given by previous reported litera tures [6,10,11].
3. Results and discussion 3.1. Structure, composition and morphology The FTIR and Raman spectra provide some information about the formation of the as-prepared nanohybrids. Fig. 1 shows the FTIR spectra of GO, TPP, TTP, TPP-GO, TTP-GO and TPP-GO-TTP. For GO, the peaks observed at 1378 (νC-OH), 1623 (νC¼C), 1731 (νC¼O), and 3405 (νO-H) cm 1 correspond the characteristic peaks of the C–OH, aromatic C¼C bond, carboxyland hydroxyl groups present in GO, respectively, which are consistent with previous reports [15]. In the case of the as-prepared
Scheme 1. Synthetic routes of TTP-GO. 2
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Scheme 2. Synthetic routes of TPP-GO.
Scheme 3. Synthetic routes of TPP-GO-TTP.
order scattering of E2g phonons from sp2 carbon atoms, respectively [17].The Raman spectrum of TPP-GO exhibits two peaks at around 1341.13 and 1596.65 cm 1, respectively, while the D- and G-bands of TTP-GO were also blue-shifted, being found at around 1344.98 and 1587.97 cm 1, respectively. After the introduction of TPP and TTP, the D- and G-bands of TPP-GO-TTP are observed at 1332.19 and 1582.89 cm 1, respectively. It should be noted that the G-band of GO shifts to lower frequency after the introduction of one electron donor compo nent, and consistent with the charge transfer from the donor component to the GO [18]. In contrast, when an electron acceptor component is introduced, the G-band shifts to higher frequency, implying the occur rence of charge transfer from the GO to the dopant component. It is thus that above results indicate that there is interfacial interactions between porphyrins and GO, which is favorable for the charge transfer from the porphyrins to the GO. Particularly, the TPP-GO-TTP exhibits the largest
nanohybrids, some characteristic peaks observed in the spectra of GO and porphyrins can be found, confirming the porphyrins have been grafted onto the GO sheets. The disappearance of the peak observed at 1378 cm 1 further implied that the porphyrins have been covalently bonded to the GO via the carboxylic acid linkage [16].In the case of the TPP-GO-TTP nanohybrid, the peak at 1731 cm 1 corresponding to the carboxyl group disappeared, and a new peak at 1710 cm 1was observed, which can be assigned to the formation of the ester bond. Similar results were also observed for TPP-GO and TTP-GO. The absence of the peak at 1623 cm 1 suggest that the introduction of porhyrins influences the aromatic system in GO, which was confirmed by the Raman spectra (Fig. 2). The Raman spectrum of GO exhibits two characteristic peaks, i.e. the D band at 1348.84 cm 1 and G band at 1599.54 cm 1, corresponding to the breathing mode of k-point phonons of A1g symmetry and the first3
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down-shift of the G band when compared to those of TPP-GO and TTP-GO, consistent with more effective charge transfer effect. Of particular note is the intensity ratio of D/G bands (ID/IG) provides a measure of the local defects and disorder in graphene. The ID/IG ratio of TPP-GO-TTP (1.066) is larger than those of GO (0.979), TPP-GO (1.048) and TTP-GO (1.035), which can be ascribed to the presence of more defects resulting from the strong interactions between porphyrins and GO. These changes indicate that the porphyrins have been covalently linked to the GO sheets, and the defective degree of TPP-GO-TTP is at high level, which is higher than those of TPP-GO and TTP-GO. Raman technique is sensitive to the electronic structure of the materials, so above results are consistent with the chemical functionalization. The formation of the as-prepared nanohybrids was further confirmed by the SEM images (Fig. 3). The GO has a sheet-like morphology with some wrinkled texture (Fig. 3a). The surface of TPP-GO (Fig. 3b), TTP-GO (Fig. 3c) and TPP-GO-TTP (Fig. 3d) are much rougher than that of GO due to the covalent grafting of porphyrins onto the GO nanosheet. Particularly, the TPP-GO-TTP has a dense surface, composed of plate-like particles with scrolled edges. The covalent attachment of porphyrins onto GO nanosheets was further confirmed by the XPS spectra. Fig. 4 displays the survey spectra of the as-prepared samples. It can be seen that only two peaks corre sponding to C and O elements were detected in the spectrum of GO. After the introduction of porphyrins, one additional peak can be observed for TPP-GO that originated from the N 1s. In the case of TTP-GO and TPPGO-TTP, two additional elements N and S can be detected, suggesting the successful grafting of porphyrins onto the GO surface. Fig. 5 shows the high-resolution XPS spectra of N 1s and S 2p for the as-prepared samples. As shown in Fig. 5a, the N 1s peak of TPP-GO is centered at 399.80 eV. In contrast, the bonding energies of N 1s for TTP-GO and TPP-GO-TTP are shifted to 399.97 and 399.73 eV. The S 2p peak of TTPGO appears at 163.88 eV. However, there is an obvious blue-shift for the S 2p peak of TPP-GO-TTP (163.88–163.67 eV) when compared to TTPGO. Both N 1s and S 2p spectra present the direct evidence of successful fabrication of porphyrins functionalized GO. The loading content of porphyrin molecules covalently grafted onto
Fig. 1. FTIR spectra of the as-prepared samples.
Fig. 2. Raman spectra of the as-prepared samples.
Fig. 3. SEM images of (a) GO, (b) TPP-GO, (c) TTP-GO, and (d) TPP-GO-TTP. 4
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corresponding to the TPP moieties is shifted from 421 to 424 nm, whereas this typical Soret absorption became even weaker and broader. Similarly, when compared to the TTP solution, the typical peak of TTP-GO gets broadened and red-shifted (428–430 nm), and the intensity is diminished. The TPP-GO-TTP nanohybrid exhibits a suppressed Soret band at around 423 nm, corresponding to a red-shift of 2 nm and a blue-shift of 5 nm compared to that of TPP and TTP, respectively. These results are consistent with the grafting of different porphyrins to GO modifying the ground state spectral performance. It should be noted that the peak shifts for the as-prepared nanohybrids are relatively small, which may be due to the fact that the para position as in the present work typically has a weaker effect [22]. As known, the occurrence of charge transfer between porphyrins and GO could be verified by the fluorescence spectra, where it has been demonstrated that the fluorescence intensity of porphyrins would decrease when they are hybridized with an electron acceptor component [23]. As shown in Fig. 7b, TPP and TTP exhibit typical porphyrin fluo rescence emission performance by exciting at the same wavelength and at constant absorption, while no fluorescence signal was observed for GO. Compared to TPP, the TPP-GO fluorescence intensity is quenched by 68%, implying the occurrence of excited-state events, i.e. energy transfer and/or electron transfer [24]. The fluorescence spectrum of TTP-GO has the similar profile as that of TTP, but its fluorescence emission quantum yield is only approximate 38% of that of TTP. It is thus that the magnitude of fluorescence quenching ofTPP-GO is larger than that of TTP-GO. Interestingly, the fluorescence intensity of TPP-GO-TTP is larger than those of TTP and TTP-GO due to the presence of TPP. However, compared to TPP-GO, the larger fluorescence quenching can be observed for TPP-GO-TTP (83%) in comparison with that of TPP, stemming from the introduction of TTP in TPP-GO-TTP. In other words, the strongest fluorescence degree was observed for TPP-GO-TTP in comparison with those of TPP-GO and TTP-GO.
Fig. 4. XPS spectra of GO, TPP-GO, TTP-GO, andTPP-GO-TTP.
the GO nanosheets for the as-prepared nanohybrids was determined by the TGA analysis [19].As shown in Fig. 6, the weight loss of GO at 800 � C is about 44.1%. In contrast, the TGA curves of TPP-GO, TTP-GO, and TPP-GO-TTPexhibited about 67.4%, 61.2% and64.6% weight loss, respectively. Therefore, the amount of porphyrins linked to GO can be determined to be about 23.3% (TPP), 17.1% (TTP) and 20.5% (TPP þ TTP) for TPP-GO, TTP-GO, and TPP-GO-TTP, respectively. Moreover, it is clear that the weight loss of the as-prepared nanohybrids is much larger than that of GO in the range of 30–800 � C, which can be ascribed to the thermolysis of porphyrin molecules covalently linked onto the GO nanosheets. In addition, the loading content of TPP and TTP function alized on the GO nanohybrids is determined to be about 26.3% and 18.2% using molar extinction coefficient (Figs. S1 and S2), which are consistent with the results of TGA. However, due to the presence of two types of porphyrins (TPP and TTP), it may be difficult to calculate the content of TPP and TTP on the TPP-GO-TTP using molar extinction coefficient. 3.2. Photophysical properties The UV–vis absorption spectra were recorded as a probe for exploring the electronic configuration of the as-prepared samples. As shown in Fig. 7a, the spectrum of GO is a typically featureless curve, while the three nanohybrids have an obvious Soret absorption band, which is possibly due to the introduced porphyrin molecules [20]. Obviously, the UV–vis absorption spectra of the as-prepared nano hybrids present a composite curve including GO and porphyrins, and the characteristic absorption peaks of porphyrins and GO were influenced by the porphyrins covalent grafted onto the GO nanosheets. The TPP has a sharp and intense Soret band at around 421 nm and four Q-bands in the range of 500–700 nm, which arethe characteristic peak of porphyrin [21]. After covalently linked with GO, the Soret band of TPP-GO
Fig. 6. TGA curves of GO, TPP-GO, TTP-GO, and TPP-GO-TTP.
Fig. 5. The amplified N 1s (a) and S 2p (b) XPS spectra of the as-prepared samples. 5
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Fig. 7. (a) UV–vis absorption and (b) steady state fluorescence spectra of the as-prepared samples.
Consistent with the results of Raman spectra, the fluorescence quench ing further confirms the efficient charge transfer effect between por phyrins (electron donor) and GO (electron acceptor), resulting in the enhanced optoelectronic performances.
TPP-GO was superior to that of TTP-GO, but inferior to that of TTP-GO-TPP. The TTP-GO-TPP has the largest dip in the transmittance of all samples, implying that it should have the best optical limiting [29]. This observation clearly suggested that the introduction of different porphyrins onto the GO nanosheets exert a crucial effect on the nonlinear absorption performances of the resultant nanohybrids. The TTP-GO-TPP exhibited better nonlinear absorption property than those of multiwalled carbon nanotubes and reduced graphene oxide cova lently functionalized by axially coordinated metal-porphyrins [10,11], but further comment is not warranted due to the different experimental geometry. Fig. 9 displays the optical limiting performances of the as-prepared samples. For the purpose of comparison, the GO was used as a stan dard. It can be clearly seen that the TPP-GO-TTP present much better optical limiting property than those of TPP-GO and TTP-GO at the same linear transmittance, consistent with the open-aperture Z-scan results. The limiting thresholds of TPP-GO, TTP-GO and TPP-GO-TTP are determined to be 1.65, 1.16 and 1.08 J/cm2, respectively. These values are considerably better than those of GO (>3.0 J/cm2) [12], C60 (2.2 J/cm2) [12] and single-wallled carbon nanotubes (2.5 J/cm2) [30], though different experimental conditions should be cautioned. The limiting thresholds and optical limiting properties of TPP and TTP were not presented in the present case, due to the normalized transmittance did not drop below 50% of the linear transmittance. Considering the donor-acceptor motif of TPP-GO, TTP-GO and TPP-GO-TTP nanohybrids in the excited-state, the increased optical limiting can be ascribed to the charge-separated excited state generated by the photoinduced electron transfer from the electron donor porphyrins to the electron acceptor GO. Indeed, the more effective charge transfer effect of TPP-GO-TTP has been confirmed by fluorescence and Raman spectra, and thus the TPP-GO-TTP exhibited the best optical limiting effect. Comparatively, the enhancement of optical limiting response of TTP-GO is the smallest among the as-prepared three nanohybrids, due to the low charge transfer efficiency. Based on above results, it is clear that the attachment of porphyrins onto the GO nanosheets obviously improved the nonlinear optical and optical limiting performances of these porphyrins-GO functionalized materials. The enhanced optical limiting performances render these nanohybrids suitable for potential applications as optical limiters in ns regime. The optoelectronic performances of GO can be tuned by the chemical functionalization (indeed the introduction of different por phyrins), so one can expect such chemical modification to result in the control and tailoring of the optical limiting performances of GO. This may also enable the generation of GO-based optical limiters, which could be comparable to, if not better than, the traditional optical devices.
3.3. Nonlinear optical performances In recent years, nonlinear optical performances of graphene have been investigated widely because of their excellent optical limiting and broadband applicability [25]. Porphyrins functionalized GO has been reported to be good optical limiting system with a combination of mechanisms [1–3]. Nevertheless, the nonlinear optical properties have hardly been investigated for functionalized GO with two different por phyrins. So it is very interesting to study the nonlinear optical (including optical limiting) performances of the nanohybrid system of GO with phenyl porphyrins and thieyl-appended porphyrins. The nonlinear optical performances of the as-prepared samples were investigated by the open-aperture Z-scan technique. The experimental process is similar to that in the literature [26]. For comparison, all samples were adjusted to have the same linear transmittance of 75% at 532 nm. As shown in Fig. 8, all samples exhibited a reduction on the focal point of the lens upon excitation at 532 nm with 4 ns pulses, indicating a decreasing transmittance for reverse saturable absorption, and consistent with the occurrence of optical limiting [27,28]. No obvious nonlinear optical signal was observed for the solvent DMSO under the same experimental process, so the observed nonlinear ab sorption effect must result from the solutes. At the focal point, the normalized transmittances of GO, TPP, TPP-GO, TTP, TTP-GO and TTP-GO-TPP decrease to be 52%, 75%, 29%, 84%, 36% and 17% of the input fluence, respectively (Fig. 8). Obviously, the nonlinear optical performances of TPP-GO, TTP-GO and TTP-GO-TPP are better than those of their components. The nonlinear absorption performance of
4. Conclusions In summary, three novel porphyrins covalently functionalized GO
Fig. 8. The open-aperture Z-scan curves of the as-prepared samples. 6
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Fig. 9. Comparison of optical limiting performance of (a) GO, (b) TTP-GO, (c) TPP-GO and TPP-GO-TTP.
nanohybrids (TPP-GO, TTP-GO and TPP-GO-TTP) have been designed and synthesized, and are characterized by various spectroscopic tech niques including FTIR, Raman, SEM, XPS and TGA spectra. Raman spectra and photophysical studies demonstrated effective charge trans fer effect from the porphyrins to the GO. The nonlinear optical and optical limiting performances were investigated by using the Z-scan technique at 532 nm under nanosecond regime. The as-prepared nano hybrids exhibited superior nonlinear absorption and optical limiting performances exciting by the 4 ns laser pulses, significantly better than their components. The enhanced nonlinear optical performances were ascribed to the effective charge transfer effect between porphyrins and GO. Particularly, the TPP-GO-TTP ternary nanohybrid showed the best nonlinear optical and optical limiting properties in comparison with those of other both binary nanohybrids, due to more effective charge transfer effect. The type of porphyrins was found to be an important factor influencing the optical nonlinearities of the porphyrins-GO nanohybrids. These results indicate that the combination GO with different porphyrins is a promising approach to design and prepare practical optical limiting devices.
References [1] Chen Y, Bai T, Dong NN, Fan F, Zhang SF, Zhuang XD, Sun J, Zhang B, Zhang XY, Wang J, Blau WJ. Graphene and its derivatives for laser protection. Prog Mater Sci 2016;84:118–57. [2] Wang AJ, Ye J, Humphrey MG, Zhang C. Graphene and carbon-nanotube nanohybrids covalently functionalized by porphyrins and phthalocyanines for optoelectronic properties. Adv Mater 2018;30:1705704. [3] Dissanayake DMAS, Cifuentes MP, Humphrey MG. Optical limiting properties of (reduced) graphene oxide covalently functionalized by coordination complexes. Coord Chem Rev 2018;375:489–513. [4] Liang GW, Tsang YH, Zeng LH, Liu X, Li J, Qu JL, Wen Q. Optical limiting properties of a few-layer MoS2/PMMA composite under excitation of ultrafast pulses. J Mater Chem C 2019;7:495–502. [5] Harris J, Gai LZ, Kubheka G, Mack J, Nyokong T, Shen Z. Optical limiting properties of 3,5-dithienylenevinylene BODIPY dyes at 532 nm. Chem Eur J 2017; 23:14507–14. [6] Wang AJ, Long LL, Meng SC, Li XF, Zhao W, Song YL, Cifuentes MP, Humphrey MG, Zhang C. Cooperative enhancement of optical nonlinearities in a porphyrin derivative bearing a pyrimidine chromophore at the periphery. Org Biomol Chem 2013;11:4250–7. [7] Zhu JH, Li YX, Chen Y, Wang J, Zhang B, Zhang JJ, Blau WJ. Graphene oxide covalently functionalized with zinc phthalocyanine for broadband optical limiting. Carbon 2011;49:1900–5. [8] Song WN, He CY, Zhang W, Gao YC, Yang YX, Wu YQ, Chen ZM, Li XC, Dong YL. Synthesis and nonlinear optical properties of reduced graphene oxide hybrid material covalently functionalized with zinc phthalocyanine. Carbon 2014;77: 1020–30. [9] Xu YF, Liu ZB, Zhang XL, Wang Y, Tian JG, Huang Y, Ma YF, Zhang XY, Chen YS. A graphene hybrid material covalently functionalized with porphyrin: synthesis and optical limiting property. Adv Mater 2009;21:1275–9. [10] Wang AJ, Song JB, Jia D, Yu W, Long LL, Song YL, Cifuentes MP, Humphrey MG, Zhang L, Shao JD, Zhang C. Functionalization of reduced graphene oxide with axially-coordinated metal-porphyrins: facile syntheses and temporally-dependent nonlinear optical properties. Inorg Chem Front 2016;3:296–305. [11] Wang AJ, Song JB, Huang ZP, Song YL, Yu W, Dong HL, Hu WP, Cifuentes MP, Humphrey MG, Zhang L, Shao JD, Zhang C. Mult-iwalled carbon nanotubes covalently functionalized by axially coordinated metal-porphyrins: facile syntheses and temporally dependent optical performance. Nano Res 2016;9:458–72. [12] Liu R, Hu JY, Zhu SQ, Lu JP, Zhu HJ. Synergistically enhanced optical limiting property of graphene oxide hybrid materials functionalized with Pt complexes. ACS Appl Mater Interfaces 2017;9:33029–40. [13] Wang AJ, Fang Y, Yu W, Long LL, Song YL, Zhao W, Cifuentes MP, Humphrey MG, Zhang C. Allyloxyporphyrin-functionalized multiwalled carbon nanotubes: synthesis by radical polymerization and enhanced optical-limiting properties. Chem Asian J 2014;9. 639-548. [14] Inoue M, Kim KS, Suzuki M, Lim JM, Shin JY, Kim D, Osuka A. Thermal fusion reactions of meso-(3-thienyl) groups in [26]hexaphyrins to produce Mobius aromatic molecules. Angew Chem Int Ed 2009;48:6687–90.
Declaration of competing interest The authors declare no conflict of interest. Acknowledgements This work was supported by the National Natural Science Foundation of China (51432006 and 51172100), the Ministry of Education of China for the Changjiang Innovation Research Team (IRT13R24), the Ministry of Education and the State Administration of Foreign Experts Affairs of China for the 111 Project (B13025), and the China Postdoctoral Foun dation (2016M601733, 2018T110446) and the Innovation Program of Shanghai Municipal Education Commission. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi. org/10.1016/j.dyepig.2019.108057. 7
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[15] Krishan MBM, Venkatramaiah N, Venkatesan R, Rao DN. Synthesis and structural, spectroscopic and nonlinear optical measurements of graphene oxide and its composites with metal and metal free porphyrins. J Mater Chem 2012;22:3059–68. [16] Liu ZB, Xu YF, Zhang XY, Zhang XL, Chen YS, Tian JG. Porphyrin and fullerene covalently functionalized graphene hybrid materials with large nonlinear optical properties. J Phys Chem B 2009;113:9681–6. [17] Wang AJ, Yu W, Fang Y, Song YL, Jia D, Long LL, Cifuentes MP, Humphrey MG, Zhang C. Facile hydrothermal synthesis and optical limiting properties of TiO2reduced graphene oxide nanocomposites. Carbon 2015;89:130–41. [18] Ouyang QY, Xu Z, Lei ZY, Dong HW, Yu HL, Qi LH, Li CY, Chen YJ. Enhanced nonlinear optical and optical limiting properties of graphene/ZnO hybrid organic glasses. Carbon 2014;67:214–20. [19] Song WN, He CY, Dong YL, Zhang W, Gao YC, Wu YQ, Chen ZM. The effects of central metals on the photophysical and nonlinear optical properties of reduced graphene oxide-metal (II) phthalocyanine hybrids. Phys Chem Chem Phys 2015;17: 7149–57. [20] X. Y. Zhang, L. L. Hou, A. Cnossen, A. C. Coleman, O. Ivashenko, P. Rudolf, B. J. van Wees, W. R. Browne, B. L. Feringa, One-pot functionalization of graphene with porphyrin through cycloaddition reactions, Chem Eur J, 1017, 17, 8957-8964. [21] Wu L, Wang JS, Feng LY, Ren JS, Wei WL, Ou XG. Lable-free ultrasensitive detection of human telomerase activity using porphyrin-functionalized graphene and electrochemiluminescence techniaue. Adv Mater 2012;24:2447–52. [22] Wang AJ, Yu W, Huang ZP, Zhou F, Song JB, Song YL, Long LL, Cifuentes MP, Humphrey MG, Zhang L, Shao JD, Zhang C. Covalent functionalization of reduced
[23] [24] [25] [26] [27] [28] [29]
[30]
8
graphene oxide with porphyrin by means of diazonium chemistry for nonlinear optical performance. Sci Rep 2016;6:23325. Du YL, Zhu K, Fang Y, Zhang SL, Zhang XR, Lu YN, Yang YC, Song YL, Wang GB. Poly(arylene ether ketone)s with pendant porphyrins: synthesis and investigation on optical limiting properties. RSC Adv 2015;5:48311–22. Karousis N, Economopoulos SP, Sarantopoulou E, Tagmatarchis N. Porphyrin counter anion in imidazolium-modified graphene-oxide. Carbon 2010;48:854–60. Wang J, Hernandez Y, Lotya M, Coleman JN, Blau WJ. Broadband nonlinear optical response of graphene dispersions. Adv Mater 2009;21:2430–5. Wang AJ, Zhao W, Yu W. Effect of acid/base on the third-order optical nonlinearity of polypyrrole. J Mol Struct 2015;1099:291–6. Zhao W, Wang Y, Wang AJ, Qian J, Zhu WH, Dou SP, Wang Q, Zhong Q, Chen QH. Novel Bi2O2CO3/polypyrrole/g-C3N4 nanocomposites with efficient photocatalytic and nonlinear optical properties. RSC Adv 2017;7:7658–70. Zhao W, Li C, Wang AJ, Lv CC, Zhu WH, Dou SP, Wang Q, Zhong Q. Polyaniline decorated Bi2MoO6 nanosheets with effective interfacial charge transfer as photocatalysts and optical limiters. Phys Chem Chem Phys 2017;19:28696–709. Zhao W, Wang AJ, Wang Y, Lv CC, Zhu WH, Dou SP, Wang Q, Zhong Q. Accessible fabrication and mechanism insight of heterostructured BiOCl/Bi2MoO6/g-C3N4 nanocomposites with efficient photosensitized activity. J Alloy Comp 2017;726: 164–72. Liu ZB, Tian JG, Guo Z, Ren DM, Du F, Zheng JY, Chen YS. Enhanced optical limiting effects in porphyrin-covalently functionalized single-walled carbon nanotubes. Adv Mater 2008;20:511–5.