- Email: [email protected]
reduced graphene oxide nanocomposites as supercapacitors electrodes
Materials Letters 159 (2015) 54–57
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
Boron nitride/reduced graphene oxide nanocomposites as supercapacitors electrodes Tao Gao n, Lai-jiang Gong, Zhao Wang, Zhong-kui Yang, Wu Pan, Li He, Jie Zhang, En-cai Ou, Yuanqin Xiong, Weijian Xu n College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China
art ic l e i nf o
a b s t r a c t
Article history: Received 5 March 2015 Received in revised form 6 May 2015 Accepted 19 June 2015 Available online 20 June 2015
Boron nitride/reduced graphene oxide (BN/RGO) nanocomposites were synthesized by a facile liquidphase exfoliation method. And the supercapacitors based on these nanocomposites show a high specific capacitance (140 F g 1 at 2 A g 1), good rate performance (71.5 F g 1 at 50 A g 1), and excellent cyclic stability (105.5% capacitance retention after 1000 cycles). These remarkable electrochemical performances imply that the BN/RGO nanocomposites would have great potential applications in supercapacitors. & 2015 Elsevier B.V. All rights reserved.
Keywords: Carbon materials Energy storage and conversion Nanocomposites
1. Introduction Supercapacitors, known as electrochemical capacitors, play a very important role in energy storage and conversion for electric devices [1]. Supercapacitors have many advantages, such as high power density, long cycle life, and fast charging/discharging rates [2]. Many carbon-based materials have been investigated as electrode materials for supercapacitors due to their intriguing properties including low cost, environmental friendliness and stability [3]. In the family of carbon materials, graphene is considered as a promising material for the next-generation supercapacitors [4] because of its high specific surface area, excellent electrical conductivity, and high theoretical specific capacitance. Ruoff first explored graphene as electrode materials, and specific capacitance of 99 F g 1 was achieved in organic electrolyte [5]. It predicts that the specific capacitances of graphene could reach 550 F g 1 [6], but the specific capacitance of most supercapacitors based on graphene is low, even lower at a large current density, it is less than 40 F g 1 at a large current density of 10 A g 1 [7,8]. Herein, we use liquid-phase exfoliation method for the synthesis of BN/RGO nanocomposites. BN consists of similar structural lattice as that found for the carbons of graphene, it can be exfoliated to small nanoparticle materials with a liquid-phase exfoliation method [9,10]. BN nanoparticle is deposited on RGO nanosheet to form BN/RGO nanocomposites, it alleviates the
agglomeration and restacking of graphene nanosheet. The asprepared BN/RGO nanocomposites show high performance in supercapacitor applications.
2. Experimental 2.1. Preparation of GO, RGO, BN, and BN/RGO GO was prepared by modified Hummers method [11]. 200 mg GO was dispersed in deionized water (200 mL) by ultrasonic vibration for 2 h. Then, 3 g ammonia and 3 mL hydrazine hydrate (80%) were added. The reaction was heated to 100 °C and stirred for 2 h. Finally, the product was washed and dried to obtain RGO nanosheet. 200 mg bulk BN was dispersed in isopropyl alcohol (200 mL) by ultrasonic vibration for 2 h. Finally, the product was washed and dried to obtain BN nanoparticle. 20 mg bulk BN and 180 mg GO were dispersed in the mixed solvents of isopropyl alcohol (100 mL) and deionized water (100 mL) by ultrasonic vibration for 2 h. Then, 3 g ammonia and 3 mL hydrazine hydrate (80%) were added. The reaction was heated to 100 °C and stirred for 2 h. Finally, the product was washed and dried to obtain BN/RGO nanocomposites. 2.2. Characterization
n
Corresponding authors. Tel.: þ 86 731 88821749; fax: þ 86 731 88821549. E-mail addresses: [email protected] (T. Gao), [email protected] (W. Xu). http://dx.doi.org/10.1016/j.matlet.2015.06.072 0167-577X/& 2015 Elsevier B.V. All rights reserved.
The products were characterized by Fourier transform infrared spectroscopy (FTIR, Affinity-1), X-ray diffraction (XRD, BRUKER
T. Gao et al. / Materials Letters 159 (2015) 54–57
D8-ADVANCE X-ray diffractometer), Laser Raman spectroscopy (Raman, LABRAM-010), scanning electron microscopy (SEM, Hitachi S-4800), transmission electron microscopy (TEM, JEOL-3010), and atomic force microscopy (AFM, Bioscope system). Nitrogen adsorption–desorption measurements were carried out on Autusorb-1C-TCD (Quantachrome, USA). Electrochemical tests were performed on an electrochemical workstation (CHI 660B) in a three electrode system in 6 M KOH solution, with Pt foil and saturated calomel electrode (SCE) as the counter electrode and reference electrode. The active material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10. The mixture was then pressed onto nickel foam and dried as the working electrode. The mass loading is about 5 mg. Cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) tests were recorded in the potential range of 0.6 V to 0.4 V. And electrochemical impedance spectroscopy (EIS) studies were conducted between 0.01 Hz to 10 kHz at amplitude of 5 mV. Specific capacitance was calculated from CV (Cs,c) and GCD curves (Cs,g) by following formulas.
Cs, c =
Cs, g =
∫ idv 2⁎m⁎ΔV ⁎S
(1)
ΔI t d mΔV
(2)
S is the scan rate, m is the mass of active material, ΔI is the discharge current, td is the discharge time, ΔV is the electrochemical window.
3. Results and discussion Fig. 1(a) shows the FTIR spectra of BN, RGO and BN/RGO. Obviously, BN exhibites two absorption peaks at 1384 cm 1 and 800 cm 1, corresponding to the bending and shearing vibrations of B–N bonds, respectively. In the spectrum of RGO, following functional groups are identified: –OH groups center at 3450 cm 1, C ¼C groups center at 1635 cm 1. In the spectrum of BN/RGO, there four mainly peaks center at 3450 cm 1, 1 1 1 and 800 cm . As shown in Fig. 1(b), a 1635 cm ,1384 cm characteristic peak centered at 1372 cm 1 is observed, which can be ascribed to the high-frequency E2g vibrating mode of h-BN [12]. RGO displays two prominent peaks at 1345 cm 1 and 1590 cm 1, corresponding to the well-documented D and G bands, respectively. For BN/RGO, there are two peaks at 1340 cm 1 and 1590 cm 1. Under the same measurement condition, the peak at 1340 cm 1 for BN/RGO showed a red-shift of 5 cm 1 in comparison with the peak at 1345 cm 1 for RGO. In addition, the crystalline structure of BN, RGO and BN/RGO were determined by powder XRD [Fig. 1(c)]. The peak at 26° correspond to the (002)
55
reflection of BN (indexed by JCPDS no. 85-1068). The peak at 24.5° correspond to the (002) reflection of RGO (indexed by JCPDS no. 75-2078). For BN/RGO, the peaks at 24.5°, 26° correspond to the (002) reflections of RGO and BN, respectively. The IR, Raman and XRD test results indicates that BN had been successfully deposited on RGO to form BN/RGO nanocomposites. Fig. 2(a) shows the SEM image of bulk BN, in which BN has a diameters of 100–300 nm and a large thickness of 30–50 nm. Fig. 2 (b) shows the SEM image of BN/RGO, it clearly shown that BN/RGO appears as a thin film and BN nanoparticle is deposited on RGO nanosheet with diameters of 80–200 nm. Fig. 2(c) shows the TEM image of BN/RGO, it shown that BN nanoparticle is deposited on RGO nanosheet with diameters of 80–200 nm. Fig. 2(d) shows the high-magnification TEM (HRTEM) images and selected area electron diffraction (SAED) pattern of BN/RGO, they are similar with that in the literature [13]. The thickness and morphology of BN/RGO were further characterized by AFM imaging [Fig. 3(a) and (b)]. The thickness of RGO nanosheet was measured to be ∼3 nm (nearly ten layers). The thickness of BN nanoparticle is measured to be ∼20 nm and the diameter is about 80 nm, which agrees well with the results of SEM and TEM. The nitrogen adsorption/desorption isotherms and pore-size distribution curves are shown in Fig. 3(c) and (d). Both RGO and BN/RGO exhibit type IV isotherms (Fig. 3(c)) with a distinct hysteresis loop. The Brunauer–Emmett–Teller (BET) specific surface areas of RGO and BN/RGO are 121 and 181 m2 g 1, respectively. Fig. 3(d) shows the pore-size distribution curves of the two samples calculated based on the Barrett–Joyner–Halenda (BJH) method. Although the surface areas of RGO and BN/RGO are very small, them still larger than some reportde literatures (such as 3D graphene are 81.7 m2 g 1 [1]; H-rGO are 142 m2 g 1 [14]). And BN/RGO has a larger surface area and a wider pore size distribution than that of RGO. The moderate specific surface area and porous structure of BN/RGO provide the possibility of efficient transport of electrons and ions in the electrode, hence leading to enhanced electrochemical property. Fig. 4(a) shows CV curves of of BN, RGO and BN/RGO electrodes under the scan rate of 10 mV s 1, respectively. It is striking to note that the maximal integral area of the CV loop for BN/RGO is larger than that for BN and RGO, which indicates the nanocomposites produce positive synergistic effects in specific capacitance. GCD test was also conducted to obtain the specific capacitances of RGO and BN/RGO. As shown in Fig. 4(b), at a current density of 2 A g 1, the specific capacitances of RGO and BN/RGO are 80 and 140 F g 1, respectively. With the addition of BN nanoparticle, the nanocomposites' capacitance increases 75%. GCD curves from 2 to 50 A g 1 are shown in Fig. 4(c). The specific capacitances of BN/ RGO at 2, 5, 10, 20, 50 A g 1 are 140, 125.5, 111, 93.2, 71.5 F g 1 respectively, which are much higher than that of RGO at the same current densities [Fig. 4(d) (e)]. BN/RGO has a good rate capability. The cycling durability of BN/RGO was tested by CV at 200 mV s 1 (Fig. 4(e)). To be surprised, the capacitance of BN/RGO increases
Fig.1. (a) IR spectra, (b) Raman spectra and (c) XRD patterns of BN, RGO and BN/RGO.
56
T. Gao et al. / Materials Letters 159 (2015) 54–57
Fig. 2. (a) SEM images of bulk BN (inset, high resolution SEM), (b) SEM images of BN/RGO (inset, high resolution SEM), (c) TEM image of BN/RGO, and (d) HRTEM images and SAED patten of BN/RGO.
Fig.3. (a), (b) AFM images of BN/RGO, (c) nitrogen adsorption–desorption isotherms and (d) pore-size distributions of RGO and BN/RGO.
5.5% after 1000 cycles, which is similar to some of the reported literature [15], it indicates that BN/RGO is very stable. Fig. 4 (f) presents the EIS studies of BN, RGO and BN/RGO. The BN electrode has a large solution and charge transfer resistance, however, the solution and charge transfer resistance of BN/RGO
are 1 Ω and 0.5 Ω, respectively. 4. Conclusions In summary, BN/RGO nanocomposite has been prepared by
T. Gao et al. / Materials Letters 159 (2015) 54–57
57
Fig.4. (a) CV curves of BN, RGO and BN/RGO, (b), (c), (d), (f) GCD curves, rate performances and EIS studies of RGO and BN/RGO, (e) Cyclic performances of BN/RGO.
liquid-phase exfoliations method. BN nanoparticle is deposited on RGO nanosheet to form BN/RGO nanocomposites. The BN/RGO electrode exhibits a high specific capacitance (140 F g 1 at 2 A g 1), good rate capability (71.5 F g 1 at 50 A g 1), and excellent cycle stability (the capacitance increases 5.5% after 1000 cycles), and a low resistance. These results suggest that BN/RGO is a promising material for high-performance supercapacitors applications.
References [1] [2] [3] [4]
J. Hu, Z. Kang, F. Li, X. Huang, Carbon 67 (2014) 221–229. A.K. Mishra, S.J. Ramaprabhu, Phys. Chem. C 115 (2011) 14006–14013. H. Jiang, P.S. Lee, C.Z. Li, Energy Environ. Sci. 6 (2013) 41–53. Z.W. Xu, Z. Li, C.M.B. Holt, X.H. Tan, H.L. Wang, B.S. Amirkhiz, T. Stephenson, D. J. Mitlin, Phys. Chem. Lett. 3 (2012) 2928–2933.
[5] M.D. Stoller, S.J. Park, Y.W. Zhu, J.H. An, R.S. Ruoff, Nano Lett. 8 (2008) 3498–3502. [6] M.F. El-Kady, V. Strong, S. Dubin, R.B. Kaner, Science 335 (2012) 1326–1330. [7] K. Gopalakrishnan, K. Moses, A. Govindaraj, C.N.R. Rao, Solid State Commun. 175–176 (2013) 43–50. [8] D. Yan, Y. Liu, Y.H. Li, R.F. Zhuo, Z.G. Wu, P.Y. Ren, et al., Mater. Lett. 127 (2014) 53–55. [9] M. Sajjad, G. Morell, P. Feng, ACS Appl. Mater. Interfaces 5 (2013) 5051–5056. [10] M.S. Xu, T. Liang, M.M. Shi, H.Z. Chen, Chem. Rev. 113 (2013) 3766–3798. [11] D.C. Marcano, D.V. Kosynkin, J.M. Berlin, et al., ACS Nano 4 (2010) 4806–4814. [12] C.J. Huang, C. Chen, X.X. Ye, W.Q. Ye, J.L. Hu, C. Xu, X.Q. Qiu, J. Mater. Chem. A 1 (2013) 12192–12197. [13] J.F. Shen, Y.Z. Hu, M. Shi, X. Lu, C. Qin, C. Li, M.Q. Ye, Chem. Mater. 21 (2009) 3514–3520. [14] J.L. Shi, W.C. Du, Y.X. Yin, Y.G. Guo, L.J. Wan, J. Mater. Chem. A 2 (2014) 10830–10834. [15] J.Y. Cao, P. Xiao, Y.C. Chen, Y. Zhou, J.H. OUYANG, D.C. Jia, Carbon 56 (2013) 383–391.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
Boron nitride/reduced graphene oxide nanocomposites as supercapacitors electrodes Tao Gao n, Lai-jiang Gong, Zhao Wang, Zhong-kui Yang, Wu Pan, Li He, Jie Zhang, En-cai Ou, Yuanqin Xiong, Weijian Xu n College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China
art ic l e i nf o
a b s t r a c t
Article history: Received 5 March 2015 Received in revised form 6 May 2015 Accepted 19 June 2015 Available online 20 June 2015
Boron nitride/reduced graphene oxide (BN/RGO) nanocomposites were synthesized by a facile liquidphase exfoliation method. And the supercapacitors based on these nanocomposites show a high specific capacitance (140 F g 1 at 2 A g 1), good rate performance (71.5 F g 1 at 50 A g 1), and excellent cyclic stability (105.5% capacitance retention after 1000 cycles). These remarkable electrochemical performances imply that the BN/RGO nanocomposites would have great potential applications in supercapacitors. & 2015 Elsevier B.V. All rights reserved.
Keywords: Carbon materials Energy storage and conversion Nanocomposites
1. Introduction Supercapacitors, known as electrochemical capacitors, play a very important role in energy storage and conversion for electric devices [1]. Supercapacitors have many advantages, such as high power density, long cycle life, and fast charging/discharging rates [2]. Many carbon-based materials have been investigated as electrode materials for supercapacitors due to their intriguing properties including low cost, environmental friendliness and stability [3]. In the family of carbon materials, graphene is considered as a promising material for the next-generation supercapacitors [4] because of its high specific surface area, excellent electrical conductivity, and high theoretical specific capacitance. Ruoff first explored graphene as electrode materials, and specific capacitance of 99 F g 1 was achieved in organic electrolyte [5]. It predicts that the specific capacitances of graphene could reach 550 F g 1 [6], but the specific capacitance of most supercapacitors based on graphene is low, even lower at a large current density, it is less than 40 F g 1 at a large current density of 10 A g 1 [7,8]. Herein, we use liquid-phase exfoliation method for the synthesis of BN/RGO nanocomposites. BN consists of similar structural lattice as that found for the carbons of graphene, it can be exfoliated to small nanoparticle materials with a liquid-phase exfoliation method [9,10]. BN nanoparticle is deposited on RGO nanosheet to form BN/RGO nanocomposites, it alleviates the
agglomeration and restacking of graphene nanosheet. The asprepared BN/RGO nanocomposites show high performance in supercapacitor applications.
2. Experimental 2.1. Preparation of GO, RGO, BN, and BN/RGO GO was prepared by modified Hummers method [11]. 200 mg GO was dispersed in deionized water (200 mL) by ultrasonic vibration for 2 h. Then, 3 g ammonia and 3 mL hydrazine hydrate (80%) were added. The reaction was heated to 100 °C and stirred for 2 h. Finally, the product was washed and dried to obtain RGO nanosheet. 200 mg bulk BN was dispersed in isopropyl alcohol (200 mL) by ultrasonic vibration for 2 h. Finally, the product was washed and dried to obtain BN nanoparticle. 20 mg bulk BN and 180 mg GO were dispersed in the mixed solvents of isopropyl alcohol (100 mL) and deionized water (100 mL) by ultrasonic vibration for 2 h. Then, 3 g ammonia and 3 mL hydrazine hydrate (80%) were added. The reaction was heated to 100 °C and stirred for 2 h. Finally, the product was washed and dried to obtain BN/RGO nanocomposites. 2.2. Characterization
n
Corresponding authors. Tel.: þ 86 731 88821749; fax: þ 86 731 88821549. E-mail addresses: [email protected] (T. Gao), [email protected] (W. Xu). http://dx.doi.org/10.1016/j.matlet.2015.06.072 0167-577X/& 2015 Elsevier B.V. All rights reserved.
The products were characterized by Fourier transform infrared spectroscopy (FTIR, Affinity-1), X-ray diffraction (XRD, BRUKER
T. Gao et al. / Materials Letters 159 (2015) 54–57
D8-ADVANCE X-ray diffractometer), Laser Raman spectroscopy (Raman, LABRAM-010), scanning electron microscopy (SEM, Hitachi S-4800), transmission electron microscopy (TEM, JEOL-3010), and atomic force microscopy (AFM, Bioscope system). Nitrogen adsorption–desorption measurements were carried out on Autusorb-1C-TCD (Quantachrome, USA). Electrochemical tests were performed on an electrochemical workstation (CHI 660B) in a three electrode system in 6 M KOH solution, with Pt foil and saturated calomel electrode (SCE) as the counter electrode and reference electrode. The active material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10. The mixture was then pressed onto nickel foam and dried as the working electrode. The mass loading is about 5 mg. Cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) tests were recorded in the potential range of 0.6 V to 0.4 V. And electrochemical impedance spectroscopy (EIS) studies were conducted between 0.01 Hz to 10 kHz at amplitude of 5 mV. Specific capacitance was calculated from CV (Cs,c) and GCD curves (Cs,g) by following formulas.
Cs, c =
Cs, g =
∫ idv 2⁎m⁎ΔV ⁎S
(1)
ΔI t d mΔV
(2)
S is the scan rate, m is the mass of active material, ΔI is the discharge current, td is the discharge time, ΔV is the electrochemical window.
3. Results and discussion Fig. 1(a) shows the FTIR spectra of BN, RGO and BN/RGO. Obviously, BN exhibites two absorption peaks at 1384 cm 1 and 800 cm 1, corresponding to the bending and shearing vibrations of B–N bonds, respectively. In the spectrum of RGO, following functional groups are identified: –OH groups center at 3450 cm 1, C ¼C groups center at 1635 cm 1. In the spectrum of BN/RGO, there four mainly peaks center at 3450 cm 1, 1 1 1 and 800 cm . As shown in Fig. 1(b), a 1635 cm ,1384 cm characteristic peak centered at 1372 cm 1 is observed, which can be ascribed to the high-frequency E2g vibrating mode of h-BN [12]. RGO displays two prominent peaks at 1345 cm 1 and 1590 cm 1, corresponding to the well-documented D and G bands, respectively. For BN/RGO, there are two peaks at 1340 cm 1 and 1590 cm 1. Under the same measurement condition, the peak at 1340 cm 1 for BN/RGO showed a red-shift of 5 cm 1 in comparison with the peak at 1345 cm 1 for RGO. In addition, the crystalline structure of BN, RGO and BN/RGO were determined by powder XRD [Fig. 1(c)]. The peak at 26° correspond to the (002)
55
reflection of BN (indexed by JCPDS no. 85-1068). The peak at 24.5° correspond to the (002) reflection of RGO (indexed by JCPDS no. 75-2078). For BN/RGO, the peaks at 24.5°, 26° correspond to the (002) reflections of RGO and BN, respectively. The IR, Raman and XRD test results indicates that BN had been successfully deposited on RGO to form BN/RGO nanocomposites. Fig. 2(a) shows the SEM image of bulk BN, in which BN has a diameters of 100–300 nm and a large thickness of 30–50 nm. Fig. 2 (b) shows the SEM image of BN/RGO, it clearly shown that BN/RGO appears as a thin film and BN nanoparticle is deposited on RGO nanosheet with diameters of 80–200 nm. Fig. 2(c) shows the TEM image of BN/RGO, it shown that BN nanoparticle is deposited on RGO nanosheet with diameters of 80–200 nm. Fig. 2(d) shows the high-magnification TEM (HRTEM) images and selected area electron diffraction (SAED) pattern of BN/RGO, they are similar with that in the literature [13]. The thickness and morphology of BN/RGO were further characterized by AFM imaging [Fig. 3(a) and (b)]. The thickness of RGO nanosheet was measured to be ∼3 nm (nearly ten layers). The thickness of BN nanoparticle is measured to be ∼20 nm and the diameter is about 80 nm, which agrees well with the results of SEM and TEM. The nitrogen adsorption/desorption isotherms and pore-size distribution curves are shown in Fig. 3(c) and (d). Both RGO and BN/RGO exhibit type IV isotherms (Fig. 3(c)) with a distinct hysteresis loop. The Brunauer–Emmett–Teller (BET) specific surface areas of RGO and BN/RGO are 121 and 181 m2 g 1, respectively. Fig. 3(d) shows the pore-size distribution curves of the two samples calculated based on the Barrett–Joyner–Halenda (BJH) method. Although the surface areas of RGO and BN/RGO are very small, them still larger than some reportde literatures (such as 3D graphene are 81.7 m2 g 1 [1]; H-rGO are 142 m2 g 1 [14]). And BN/RGO has a larger surface area and a wider pore size distribution than that of RGO. The moderate specific surface area and porous structure of BN/RGO provide the possibility of efficient transport of electrons and ions in the electrode, hence leading to enhanced electrochemical property. Fig. 4(a) shows CV curves of of BN, RGO and BN/RGO electrodes under the scan rate of 10 mV s 1, respectively. It is striking to note that the maximal integral area of the CV loop for BN/RGO is larger than that for BN and RGO, which indicates the nanocomposites produce positive synergistic effects in specific capacitance. GCD test was also conducted to obtain the specific capacitances of RGO and BN/RGO. As shown in Fig. 4(b), at a current density of 2 A g 1, the specific capacitances of RGO and BN/RGO are 80 and 140 F g 1, respectively. With the addition of BN nanoparticle, the nanocomposites' capacitance increases 75%. GCD curves from 2 to 50 A g 1 are shown in Fig. 4(c). The specific capacitances of BN/ RGO at 2, 5, 10, 20, 50 A g 1 are 140, 125.5, 111, 93.2, 71.5 F g 1 respectively, which are much higher than that of RGO at the same current densities [Fig. 4(d) (e)]. BN/RGO has a good rate capability. The cycling durability of BN/RGO was tested by CV at 200 mV s 1 (Fig. 4(e)). To be surprised, the capacitance of BN/RGO increases
Fig.1. (a) IR spectra, (b) Raman spectra and (c) XRD patterns of BN, RGO and BN/RGO.
56
T. Gao et al. / Materials Letters 159 (2015) 54–57
Fig. 2. (a) SEM images of bulk BN (inset, high resolution SEM), (b) SEM images of BN/RGO (inset, high resolution SEM), (c) TEM image of BN/RGO, and (d) HRTEM images and SAED patten of BN/RGO.
Fig.3. (a), (b) AFM images of BN/RGO, (c) nitrogen adsorption–desorption isotherms and (d) pore-size distributions of RGO and BN/RGO.
5.5% after 1000 cycles, which is similar to some of the reported literature [15], it indicates that BN/RGO is very stable. Fig. 4 (f) presents the EIS studies of BN, RGO and BN/RGO. The BN electrode has a large solution and charge transfer resistance, however, the solution and charge transfer resistance of BN/RGO
are 1 Ω and 0.5 Ω, respectively. 4. Conclusions In summary, BN/RGO nanocomposite has been prepared by
T. Gao et al. / Materials Letters 159 (2015) 54–57
57
Fig.4. (a) CV curves of BN, RGO and BN/RGO, (b), (c), (d), (f) GCD curves, rate performances and EIS studies of RGO and BN/RGO, (e) Cyclic performances of BN/RGO.
liquid-phase exfoliations method. BN nanoparticle is deposited on RGO nanosheet to form BN/RGO nanocomposites. The BN/RGO electrode exhibits a high specific capacitance (140 F g 1 at 2 A g 1), good rate capability (71.5 F g 1 at 50 A g 1), and excellent cycle stability (the capacitance increases 5.5% after 1000 cycles), and a low resistance. These results suggest that BN/RGO is a promising material for high-performance supercapacitors applications.
References [1] [2] [3] [4]
J. Hu, Z. Kang, F. Li, X. Huang, Carbon 67 (2014) 221–229. A.K. Mishra, S.J. Ramaprabhu, Phys. Chem. C 115 (2011) 14006–14013. H. Jiang, P.S. Lee, C.Z. Li, Energy Environ. Sci. 6 (2013) 41–53. Z.W. Xu, Z. Li, C.M.B. Holt, X.H. Tan, H.L. Wang, B.S. Amirkhiz, T. Stephenson, D. J. Mitlin, Phys. Chem. Lett. 3 (2012) 2928–2933.
[5] M.D. Stoller, S.J. Park, Y.W. Zhu, J.H. An, R.S. Ruoff, Nano Lett. 8 (2008) 3498–3502. [6] M.F. El-Kady, V. Strong, S. Dubin, R.B. Kaner, Science 335 (2012) 1326–1330. [7] K. Gopalakrishnan, K. Moses, A. Govindaraj, C.N.R. Rao, Solid State Commun. 175–176 (2013) 43–50. [8] D. Yan, Y. Liu, Y.H. Li, R.F. Zhuo, Z.G. Wu, P.Y. Ren, et al., Mater. Lett. 127 (2014) 53–55. [9] M. Sajjad, G. Morell, P. Feng, ACS Appl. Mater. Interfaces 5 (2013) 5051–5056. [10] M.S. Xu, T. Liang, M.M. Shi, H.Z. Chen, Chem. Rev. 113 (2013) 3766–3798. [11] D.C. Marcano, D.V. Kosynkin, J.M. Berlin, et al., ACS Nano 4 (2010) 4806–4814. [12] C.J. Huang, C. Chen, X.X. Ye, W.Q. Ye, J.L. Hu, C. Xu, X.Q. Qiu, J. Mater. Chem. A 1 (2013) 12192–12197. [13] J.F. Shen, Y.Z. Hu, M. Shi, X. Lu, C. Qin, C. Li, M.Q. Ye, Chem. Mater. 21 (2009) 3514–3520. [14] J.L. Shi, W.C. Du, Y.X. Yin, Y.G. Guo, L.J. Wan, J. Mater. Chem. A 2 (2014) 10830–10834. [15] J.Y. Cao, P. Xiao, Y.C. Chen, Y. Zhou, J.H. OUYANG, D.C. Jia, Carbon 56 (2013) 383–391.