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CdSe nanoparticles co-deposited SnO2(TiO2) spherical structure film for photoelectrochemical application
Materials Letters 239 (2019) 59–62
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
CdS/CdSe nanoparticles co-deposited SnO2(TiO2) spherical structure film for photoelectrochemical application Xiaoming Zhou a,⇑, Xinyue Zhang a, Benyi Li a, Risong Li a, Lili Gao b, Songbo Zhang b, Miao Zhang b, Jiajia Mu b, Xin Zhang a a b
College of Materials Science and Engineering, Beihua University, Jilin, China College of Science, Beihua University, Jilin, China
a r t i c l e
i n f o
Article history: Received 4 November 2018 Received in revised form 2 December 2018 Accepted 11 December 2018 Available online 19 December 2018 Keywords: Thin films Nanocomposites Heterostructure Photoelectrochemisty
a b s t r a c t Herein, SnO2 spherical structure was directly deposited on FTO substrate by hydrothermal synthesis. As light absorber, CdS and CdSe nanoparticles were assembled onto the TiCl4-treated SnO2 spherical particles (SnO2(TiO2)) films by using SILAR method. The number of CdS and CdSe deposition cycles that influence the optical and photoelectrochemical performance of the photoelectrodes are evaluated. The best-performed sample is the co-deposition of 5 cycles of CdS and 4 cycles of CdSe on SnO2(TiO2) photoelectrode, and its photocurrent density is about 2.61 mA cm 2 versus Ag/AgCl at 0 V. The significant photoelectrochemical performance is due to a synergistic contribution from the enhanced light absorption range of the hybrid nanocomposite and the formation of type-II heterostructure, which plays important role in the effective charge separation process. Our results show that CdS/CdSe co-deposition SnO2(TiO2) photoelectrode may have great potential application in photovoltaic field. Ó 2018 Elsevier B.V. All rights reserved.
1. Introduction Tin dioxide (SnO2), one of the important metal oxide semiconductors, is considered as a suitable material for extensive investigation in the photovoltaic field. SnO2 has its own advantages and characteristics. For example it has high electron mobility (100–200 cm2 V 1 S 1) and a large bandgap of 3.6 eV [1]. Higher electron mobility facilitates more rapid transfer of photo-injected electrons to the collection electrode and large band-gap can make SnO2 create fewer oxidative holes in the valence band (VB) under UV illumination comparing to that in TiO2 (3.2 eV) [2]. Moreover, the conduction band (CB) of SnO2 is more positive compared to TiO2, which suggests a more efficient charge injection from low band gap. In addition to charge separation and charge transport, the generation of photo-induced carriers is also necessary for photoelectrochemical cells photoelectrode [3,4]. In order to achieve these goals, photoelectrodes with the following two structural features are desirable. Firstly, it is desirable to have large specific surface area so as to carry more light absorbing materials and to produce more photogenerated carriers. Secondly, a structure with excellent light scattering ability is required, which will maximize the use of ⇑ Corresponding author. E-mail address: [email protected] (X. Zhou). https://doi.org/10.1016/j.matlet.2018.12.054 0167-577X/Ó 2018 Elsevier B.V. All rights reserved.
the light in the sample to produce photogenerated carriers as many as possible. Now, the idea is realized with a submicron-sized mesoporous, which are aggregated by 1D single crystalline nanostructures. This structure has both large surface areas and excellent light scattering capability [5,6]. In addition, the 1D single crystalline nanostructure can provide fast pathways for electron transport. However, it should be noted that the study of such structure photoelectrodes are mainly focused on TiO2. There is almost no report on the SnO2 photoelectrodes of this structure. In this study, the SnO2(TiO2) spherical structure was prepared by hydrothermal approach and treated by TiCl4. The spherical particles have a submicron size and agglomerated by many 1D nanorods. The photoelectrochemical properties of the CdS/CdSe nanoparticles co-deposited SnO2(TiO2) spherical particles films were investigated. As far as we know, there is no report on CdS/ CdSe nanoparticles co-deposited SnO2(TiO2) spherical particles structure for photoelectrochemical cells. 2. Experimental Preparation of SnO2 spherical particles film, deposition of CdS/CdSe nanoparticles and test instruments are detailed in supplementary material and our previous article [7,8]. Na2SeSO3 was used as Se source. The deposition time and temperature in Se source was 1 h and 50 °C, respectively. Photoelectrochemical
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test used three electrodes system. A mixed aqueous solution of 0.35 M Na2SO3 and 0.25 M Na2S was used as electrolyte. The light intensity was 100 mW cm 2. 3. Results and discussion As shown in Fig. 1, the XRD pattern of SnO2 spherical particles film without TiCl4 treatment can be agreed with the SnO2 (rutile phase, 41-1445). No significant difference is detected in XRD spectra of the SnO2 spherical particles film after TiCl4 treatment (SnO2(TiO2)). It should be noted that the introduction of TiCl4 have an important role here. After the SnO2 spherical particles film is treated by TiCl4, the combination between the SnO2 spherical particles film and FTO becomes even stronger, which will be beneficial to the electron transfer [9]. Similarly, no other typical CdS or CdSe peaks are observed in the XRD pattern of SnO2(TiO2)/CdS(5)/CdSe (4) heterostructure sample, which might be due to its low amount and relatively low diffraction intensity of CdS and CdSe nanoparticles in comparison to that of SnO2.
Fig. 1. The XRD patterns of the samples.
Fig. 2a is a top view image of SnO2 film, which reveals that densified SnO2 spherical particles have covered on the surface of the FTO substrate and the thickness of the SnO2 film is about 2.1 lm. Fig. 2b shows that the spherical structures are agglomerated by a large number of 1D nanorods. The TEM image of Fig. 2c shows clearly that the spherical structures are agglomerated by nanorods. Fig. 2d is the HRTEM image of a typical nanorod, which clearly illustrates that the nanorod has smooth surface. Lattice fringe with spacing of 0.334 nm is observed, which correspond to the (1 1 0) lattice planes of rutile phase SnO2 (card 41-1445). This also shows that the nanorods have good crystallinity and grow along the [0 0 1] direction. The Fourier-transform patterns (FFT) (inset in Fig. 2d) and its HRTEM image reveal that the nanorods are single crystal structure. Fig. 2e is a HRTEM image of the sample of SnO2(TiO2)/CdS(5)/CdSe(4). The lattice fringes with interplanar spacings of 0.334 nm are well matched to the (1 1 0) lattice planes of SnO2. The 0.335 nm fringes of the nanoparticles on the SnO2 nanorod are matched to the (1 1 1) planes of the CdS (cubic phase, card 80-0019). The observed 0.214 nm and 0.352 nm fringe of the CdS nanoparticles are matched to the (1 1 0) and (0 0 2) planes of the CdSe (hexagonal phase, card 08-0459). In the EDS spectrum (Fig. 2f), there are six major elements observed, Sn, O, Ti, Cd, S and Se, which are resulted from the SnO2, TiO2, CdS and CdSe nanoparticles, respectively. The atomic ratio of Cd, S and Se in the sample is about 4.08%, 1.52% and 2.52%, respectively. The approximately 1:1 M ratio of S and Se to Cd means high quality CdS and CdSe are successfully synthesized. STEM-EDX elemental mapping and STEM images of the sample are shown in Fig. 2g, which are corresponds to the distribution of Sn, O, Ti, Cd, S and Se elements in the sample of SnO2(TiO2)/CdS(5)/CdSe(4) and no impurities present in them. These findings further confirmed the successful deposition of CdS and CdSe nanoparticles on the SnO2(TiO2) spherical structure. Fig. 3a shows the UV-vis absorption spectrum of the samples. The SnO2(TiO2) film can only absorb ultraviolet light due to its large energy gap. After 5 cycles of CdS nanoparticles deposition, the light absorption range is extended to about 520 nm. When CdSe nanoparticles grow on SnO2(TiO2)/CdS(5) film, the codeposited films have wider wavelength absorption than that of SnO2(TiO2)/CdS(5) film. As the number of CdSe deposition cycles
Fig. 2. (a), (b) FESEM images and (c) TEM image of the SnO2 spheres; (d) HRTEM image and its FFT of one typical nanorod of the spherical structure; (e) HRTEM image, (f) EDS spectrum and (g) STEM-EDX elemental mapping of the SnO2(TiO2)/CdS(5)/CdSe(4) electrode.
X. Zhou et al. / Materials Letters 239 (2019) 59–62
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Fig. 3. (a) UV-vis absorption spectra, (b) and (c) the J-V curves of the samples; (d) energy band of SnO2(TiO2)-CdS-CdSe coupled semiconductor.
increasing, the light absorption range of the samples increase gradually due to the size-induced electronic quantization phenomena, which is considered to the result of the increased deposition of CdSe nanoparticles. Fig. 3b shows the current density versus potential (J-V) characteristics of the CdS nanoparticles-deposited SnO2(TiO2) photoelectrode for different cycles. The photocurrent density of the SnO2(TiO2) sample is about 0.26 mA cm 2 versus Ag/AgCl at 0 V. The maximum photocurrent density is 5 cycles of CdS nanoparticles deposited film. The photocurrent density is about 1.50 mA cm 2. We keep the deposition cycles of CdS at 5 cycles, while depositing them with CdSe layers. In Fig. 3c, as the number of CdSe deposition cycles increases, the photocurrent density of the samples improve significantly. When 4 cycles of CdSe are deposited, the current density reaches a maximum value of about 2.61 mA cm 2 at 0 V versus Ag/AgCl. For the bare SnO2(TiO2) photoelectrode, the open circuit photovoltage is only 0.79 V. When 5 cycles of CdS and 4 cycles of CdSe are deposited, the open circuit voltage increases to about 0.87 V, which indicates that a heterosturcture has formed between CdSe、CdS and SnO2(TiO2). This is because the Fermi level shift to a more negative potential [10], suggesting more efficient separation of photogenerated carriers over the SnO2(TiO2)-CdS-CdSe heterostructures. When the CdSe deposition cycles number increases to 5, the photocurrent value decreased. This is because too much CdSe can become a potential barrier in photocarrier transport and can block the pore on the surface of the photoelectrode. The contact area between photoelectrode and electrolyte will decrease, which is not conducive to the transfer of electrons between the electrolyte and photoelectrode interface [7]. The superior photoelectrochemical performance of SnO2(TiO2)/ CdS(5)/CdSe(4) photoelectrode can be attributed to the following reasons. Firstly, compared with SnO2(TiO2) and SnO2(TiO2)/CdS photoelectrodes, this CdS/CdSe co-deposited SnO2(TiO2) electrodes have wider and stronger visible light absorption, which can greatly improve the utilization rate of the solar energy. Secondly, the formation of type-II heterostructures for SnO2(TiO2)/CdS(5)/CdSe(4)
photoelectrode (Fig. 3d) plays an important role in the effective charge separation and can help to extend the lifetime of photogenerated carriers [11]. Thirdly, SnO2 spherical structures are agglomerated by a large number of 1D single crystal nanorods. This structure has a large specific surface area and good light scattering ability, while the single crystal nanorods can facilitate the transmission of photogenerated electrons [7]. In addition, when SnO2 film was treated by TiCl4, the surface of SnO2 can be effectively passivated and the combination between the SnO2 spherical particles and FTO become stronger, which are beneficial to the electron transfer and subsequently can enhance the electron transfer efficiency [11]. 4. Conclusions In this study, CdS/CdSe nanoparticles co-deposited SnO2(TiO2) spherical structure films on FTO substrates were prepared. The SnO2(TiO2) spherical structures are agglomerated by a large number of 1D single crystal nanorods. The number of CdS and CdSe deposition cycles has an important influence on the photoelectrochemical properties of the photoelectrode. The optimal photoelectrode is SnO2(TiO2)/CdS(5)/CdSe(4) sample, its photocurrent density is about 2.61 mA cm 2 versus Ag/AgCl at 0 V, which can be attributed to the synergetic effect in strong visible-light absorption and heterojunction structure. Acknowledgments This work was financially supported by the National Natural Science Foundation of China (No.61504002, 11504007 and 51602006), the Scientific and Technological Research Project of Jilin Provincial Education Department (No. JJKH20170026KJ and 2016049), Science and Technology Development Program of Jilin Province (NO. 20170520108JH), College Students Innovation and Entrepreneurship Training Program of Jilin Province (NO.201711923097).
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Conflicts of interest
References
The authors declare that the publication of this article has no conflicts of interest.
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11]
Declaration of interest statement The authors declare that there are no competing interests regarding the publication of this paper. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.matlet.2018.12.054.
F.Y. Xie, Y.F. Li, J. Dou, et al., J. Power. Sources 336 (2016) 143–149. Y.J. Kim, K.H. Kim, P. Kang, et al., Langmuir 28 (2012) 10620–10626. Q. Zhang, K. Park, J. Xie, et al., Adv. Energy Mater. 1 (2011) 988–1001. T.Y. Tsai, S.Y. Lu, Electrochem. Commun. 11 (2009) 2180–2183. D. Chen, F. Huang, Y.B. Cheng, R.A. Caruso, Adv. Mater. 21 (2009) 2206–2210. Y.J. Kim, M.H. Lee, H.J. Kim, et al., Adv. Mater. 21 (2009) 3668–3673. X.M. Zhou, W.Y. Fu, H.B. Yang, et al., Electrochimi. Acta. 89 (2013) 510–515. J.W. Ma, S. Su, W.Y. Fu, et al., Crystengcomm. 16 (2014) 2910–2916. Y.F. Wang, J.W. Li, Y.F. Hou, et al., Chem. Eur. J. 16 (2010) 8620–8625. Y. Huang, J. Chen, W. Zou, et al., Dalton. Trans. 45 (2016) 1160–1165. M.A. Hossain, J.R. Jennings, Z.Y. Koh, Q. Wang, ACS Nano 5 (2011) 3172–3181.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
CdS/CdSe nanoparticles co-deposited SnO2(TiO2) spherical structure film for photoelectrochemical application Xiaoming Zhou a,⇑, Xinyue Zhang a, Benyi Li a, Risong Li a, Lili Gao b, Songbo Zhang b, Miao Zhang b, Jiajia Mu b, Xin Zhang a a b
College of Materials Science and Engineering, Beihua University, Jilin, China College of Science, Beihua University, Jilin, China
a r t i c l e
i n f o
Article history: Received 4 November 2018 Received in revised form 2 December 2018 Accepted 11 December 2018 Available online 19 December 2018 Keywords: Thin films Nanocomposites Heterostructure Photoelectrochemisty
a b s t r a c t Herein, SnO2 spherical structure was directly deposited on FTO substrate by hydrothermal synthesis. As light absorber, CdS and CdSe nanoparticles were assembled onto the TiCl4-treated SnO2 spherical particles (SnO2(TiO2)) films by using SILAR method. The number of CdS and CdSe deposition cycles that influence the optical and photoelectrochemical performance of the photoelectrodes are evaluated. The best-performed sample is the co-deposition of 5 cycles of CdS and 4 cycles of CdSe on SnO2(TiO2) photoelectrode, and its photocurrent density is about 2.61 mA cm 2 versus Ag/AgCl at 0 V. The significant photoelectrochemical performance is due to a synergistic contribution from the enhanced light absorption range of the hybrid nanocomposite and the formation of type-II heterostructure, which plays important role in the effective charge separation process. Our results show that CdS/CdSe co-deposition SnO2(TiO2) photoelectrode may have great potential application in photovoltaic field. Ó 2018 Elsevier B.V. All rights reserved.
1. Introduction Tin dioxide (SnO2), one of the important metal oxide semiconductors, is considered as a suitable material for extensive investigation in the photovoltaic field. SnO2 has its own advantages and characteristics. For example it has high electron mobility (100–200 cm2 V 1 S 1) and a large bandgap of 3.6 eV [1]. Higher electron mobility facilitates more rapid transfer of photo-injected electrons to the collection electrode and large band-gap can make SnO2 create fewer oxidative holes in the valence band (VB) under UV illumination comparing to that in TiO2 (3.2 eV) [2]. Moreover, the conduction band (CB) of SnO2 is more positive compared to TiO2, which suggests a more efficient charge injection from low band gap. In addition to charge separation and charge transport, the generation of photo-induced carriers is also necessary for photoelectrochemical cells photoelectrode [3,4]. In order to achieve these goals, photoelectrodes with the following two structural features are desirable. Firstly, it is desirable to have large specific surface area so as to carry more light absorbing materials and to produce more photogenerated carriers. Secondly, a structure with excellent light scattering ability is required, which will maximize the use of ⇑ Corresponding author. E-mail address: [email protected] (X. Zhou). https://doi.org/10.1016/j.matlet.2018.12.054 0167-577X/Ó 2018 Elsevier B.V. All rights reserved.
the light in the sample to produce photogenerated carriers as many as possible. Now, the idea is realized with a submicron-sized mesoporous, which are aggregated by 1D single crystalline nanostructures. This structure has both large surface areas and excellent light scattering capability [5,6]. In addition, the 1D single crystalline nanostructure can provide fast pathways for electron transport. However, it should be noted that the study of such structure photoelectrodes are mainly focused on TiO2. There is almost no report on the SnO2 photoelectrodes of this structure. In this study, the SnO2(TiO2) spherical structure was prepared by hydrothermal approach and treated by TiCl4. The spherical particles have a submicron size and agglomerated by many 1D nanorods. The photoelectrochemical properties of the CdS/CdSe nanoparticles co-deposited SnO2(TiO2) spherical particles films were investigated. As far as we know, there is no report on CdS/ CdSe nanoparticles co-deposited SnO2(TiO2) spherical particles structure for photoelectrochemical cells. 2. Experimental Preparation of SnO2 spherical particles film, deposition of CdS/CdSe nanoparticles and test instruments are detailed in supplementary material and our previous article [7,8]. Na2SeSO3 was used as Se source. The deposition time and temperature in Se source was 1 h and 50 °C, respectively. Photoelectrochemical
60
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test used three electrodes system. A mixed aqueous solution of 0.35 M Na2SO3 and 0.25 M Na2S was used as electrolyte. The light intensity was 100 mW cm 2. 3. Results and discussion As shown in Fig. 1, the XRD pattern of SnO2 spherical particles film without TiCl4 treatment can be agreed with the SnO2 (rutile phase, 41-1445). No significant difference is detected in XRD spectra of the SnO2 spherical particles film after TiCl4 treatment (SnO2(TiO2)). It should be noted that the introduction of TiCl4 have an important role here. After the SnO2 spherical particles film is treated by TiCl4, the combination between the SnO2 spherical particles film and FTO becomes even stronger, which will be beneficial to the electron transfer [9]. Similarly, no other typical CdS or CdSe peaks are observed in the XRD pattern of SnO2(TiO2)/CdS(5)/CdSe (4) heterostructure sample, which might be due to its low amount and relatively low diffraction intensity of CdS and CdSe nanoparticles in comparison to that of SnO2.
Fig. 1. The XRD patterns of the samples.
Fig. 2a is a top view image of SnO2 film, which reveals that densified SnO2 spherical particles have covered on the surface of the FTO substrate and the thickness of the SnO2 film is about 2.1 lm. Fig. 2b shows that the spherical structures are agglomerated by a large number of 1D nanorods. The TEM image of Fig. 2c shows clearly that the spherical structures are agglomerated by nanorods. Fig. 2d is the HRTEM image of a typical nanorod, which clearly illustrates that the nanorod has smooth surface. Lattice fringe with spacing of 0.334 nm is observed, which correspond to the (1 1 0) lattice planes of rutile phase SnO2 (card 41-1445). This also shows that the nanorods have good crystallinity and grow along the [0 0 1] direction. The Fourier-transform patterns (FFT) (inset in Fig. 2d) and its HRTEM image reveal that the nanorods are single crystal structure. Fig. 2e is a HRTEM image of the sample of SnO2(TiO2)/CdS(5)/CdSe(4). The lattice fringes with interplanar spacings of 0.334 nm are well matched to the (1 1 0) lattice planes of SnO2. The 0.335 nm fringes of the nanoparticles on the SnO2 nanorod are matched to the (1 1 1) planes of the CdS (cubic phase, card 80-0019). The observed 0.214 nm and 0.352 nm fringe of the CdS nanoparticles are matched to the (1 1 0) and (0 0 2) planes of the CdSe (hexagonal phase, card 08-0459). In the EDS spectrum (Fig. 2f), there are six major elements observed, Sn, O, Ti, Cd, S and Se, which are resulted from the SnO2, TiO2, CdS and CdSe nanoparticles, respectively. The atomic ratio of Cd, S and Se in the sample is about 4.08%, 1.52% and 2.52%, respectively. The approximately 1:1 M ratio of S and Se to Cd means high quality CdS and CdSe are successfully synthesized. STEM-EDX elemental mapping and STEM images of the sample are shown in Fig. 2g, which are corresponds to the distribution of Sn, O, Ti, Cd, S and Se elements in the sample of SnO2(TiO2)/CdS(5)/CdSe(4) and no impurities present in them. These findings further confirmed the successful deposition of CdS and CdSe nanoparticles on the SnO2(TiO2) spherical structure. Fig. 3a shows the UV-vis absorption spectrum of the samples. The SnO2(TiO2) film can only absorb ultraviolet light due to its large energy gap. After 5 cycles of CdS nanoparticles deposition, the light absorption range is extended to about 520 nm. When CdSe nanoparticles grow on SnO2(TiO2)/CdS(5) film, the codeposited films have wider wavelength absorption than that of SnO2(TiO2)/CdS(5) film. As the number of CdSe deposition cycles
Fig. 2. (a), (b) FESEM images and (c) TEM image of the SnO2 spheres; (d) HRTEM image and its FFT of one typical nanorod of the spherical structure; (e) HRTEM image, (f) EDS spectrum and (g) STEM-EDX elemental mapping of the SnO2(TiO2)/CdS(5)/CdSe(4) electrode.
X. Zhou et al. / Materials Letters 239 (2019) 59–62
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Fig. 3. (a) UV-vis absorption spectra, (b) and (c) the J-V curves of the samples; (d) energy band of SnO2(TiO2)-CdS-CdSe coupled semiconductor.
increasing, the light absorption range of the samples increase gradually due to the size-induced electronic quantization phenomena, which is considered to the result of the increased deposition of CdSe nanoparticles. Fig. 3b shows the current density versus potential (J-V) characteristics of the CdS nanoparticles-deposited SnO2(TiO2) photoelectrode for different cycles. The photocurrent density of the SnO2(TiO2) sample is about 0.26 mA cm 2 versus Ag/AgCl at 0 V. The maximum photocurrent density is 5 cycles of CdS nanoparticles deposited film. The photocurrent density is about 1.50 mA cm 2. We keep the deposition cycles of CdS at 5 cycles, while depositing them with CdSe layers. In Fig. 3c, as the number of CdSe deposition cycles increases, the photocurrent density of the samples improve significantly. When 4 cycles of CdSe are deposited, the current density reaches a maximum value of about 2.61 mA cm 2 at 0 V versus Ag/AgCl. For the bare SnO2(TiO2) photoelectrode, the open circuit photovoltage is only 0.79 V. When 5 cycles of CdS and 4 cycles of CdSe are deposited, the open circuit voltage increases to about 0.87 V, which indicates that a heterosturcture has formed between CdSe、CdS and SnO2(TiO2). This is because the Fermi level shift to a more negative potential [10], suggesting more efficient separation of photogenerated carriers over the SnO2(TiO2)-CdS-CdSe heterostructures. When the CdSe deposition cycles number increases to 5, the photocurrent value decreased. This is because too much CdSe can become a potential barrier in photocarrier transport and can block the pore on the surface of the photoelectrode. The contact area between photoelectrode and electrolyte will decrease, which is not conducive to the transfer of electrons between the electrolyte and photoelectrode interface [7]. The superior photoelectrochemical performance of SnO2(TiO2)/ CdS(5)/CdSe(4) photoelectrode can be attributed to the following reasons. Firstly, compared with SnO2(TiO2) and SnO2(TiO2)/CdS photoelectrodes, this CdS/CdSe co-deposited SnO2(TiO2) electrodes have wider and stronger visible light absorption, which can greatly improve the utilization rate of the solar energy. Secondly, the formation of type-II heterostructures for SnO2(TiO2)/CdS(5)/CdSe(4)
photoelectrode (Fig. 3d) plays an important role in the effective charge separation and can help to extend the lifetime of photogenerated carriers [11]. Thirdly, SnO2 spherical structures are agglomerated by a large number of 1D single crystal nanorods. This structure has a large specific surface area and good light scattering ability, while the single crystal nanorods can facilitate the transmission of photogenerated electrons [7]. In addition, when SnO2 film was treated by TiCl4, the surface of SnO2 can be effectively passivated and the combination between the SnO2 spherical particles and FTO become stronger, which are beneficial to the electron transfer and subsequently can enhance the electron transfer efficiency [11]. 4. Conclusions In this study, CdS/CdSe nanoparticles co-deposited SnO2(TiO2) spherical structure films on FTO substrates were prepared. The SnO2(TiO2) spherical structures are agglomerated by a large number of 1D single crystal nanorods. The number of CdS and CdSe deposition cycles has an important influence on the photoelectrochemical properties of the photoelectrode. The optimal photoelectrode is SnO2(TiO2)/CdS(5)/CdSe(4) sample, its photocurrent density is about 2.61 mA cm 2 versus Ag/AgCl at 0 V, which can be attributed to the synergetic effect in strong visible-light absorption and heterojunction structure. Acknowledgments This work was financially supported by the National Natural Science Foundation of China (No.61504002, 11504007 and 51602006), the Scientific and Technological Research Project of Jilin Provincial Education Department (No. JJKH20170026KJ and 2016049), Science and Technology Development Program of Jilin Province (NO. 20170520108JH), College Students Innovation and Entrepreneurship Training Program of Jilin Province (NO.201711923097).
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X. Zhou et al. / Materials Letters 239 (2019) 59–62
Conflicts of interest
References
The authors declare that the publication of this article has no conflicts of interest.
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11]
Declaration of interest statement The authors declare that there are no competing interests regarding the publication of this paper. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.matlet.2018.12.054.
F.Y. Xie, Y.F. Li, J. Dou, et al., J. Power. Sources 336 (2016) 143–149. Y.J. Kim, K.H. Kim, P. Kang, et al., Langmuir 28 (2012) 10620–10626. Q. Zhang, K. Park, J. Xie, et al., Adv. Energy Mater. 1 (2011) 988–1001. T.Y. Tsai, S.Y. Lu, Electrochem. Commun. 11 (2009) 2180–2183. D. Chen, F. Huang, Y.B. Cheng, R.A. Caruso, Adv. Mater. 21 (2009) 2206–2210. Y.J. Kim, M.H. Lee, H.J. Kim, et al., Adv. Mater. 21 (2009) 3668–3673. X.M. Zhou, W.Y. Fu, H.B. Yang, et al., Electrochimi. Acta. 89 (2013) 510–515. J.W. Ma, S. Su, W.Y. Fu, et al., Crystengcomm. 16 (2014) 2910–2916. Y.F. Wang, J.W. Li, Y.F. Hou, et al., Chem. Eur. J. 16 (2010) 8620–8625. Y. Huang, J. Chen, W. Zou, et al., Dalton. Trans. 45 (2016) 1160–1165. M.A. Hossain, J.R. Jennings, Z.Y. Koh, Q. Wang, ACS Nano 5 (2011) 3172–3181.