Co-reporter:Qingsong Jiang, Ni Xiong, Kai Pan, Mei Wu, Yuhan Zhou
Materials Science in Semiconductor Processing 2017 Volume 66(Volume 66) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.mssp.2017.04.030
Fabrication of low-cost counter electrodes with high electrocatalytic performance is one of the most important challenges for dye-sensitized solar cells. Vertically aligned Ni3Se2 arrays with dendritic-like structure have been synthesized by a simple solvothermal method in this paper. Due to direct electron transfer and more catalytic active sites, Ni3Se2 arrays can be used as counter electrodes of dye-sensitized solar cells. The dye-sensitized solar cell based on Ni3Se2 array counter electrode shows a high photovoltaic performance with a high photoelectrical conversion efficiency of 4.62%, which is comparable with that of the dye-sensitized solar cell based on platinum counter electrode. To understand the chemical catalysis toward I3- reduction and interfacial charge transfer, the Ni3Se2 array counter electrode has been quantitatively investigated by the electrochemical measurements. The results indicate that the Ni3Se2 array counter electrode exhibits good catalytic activity and direct electron transfer for the reduction of I3-. Our research work will provide insight into the design and fabrication of counter electrode materials with high electrocatalytic performance for dye-sensitized solar cells.
Co-reporter:Qingsong Jiang, Kai Pan, Chun-Sing Lee, Guang Hu, Yuhan Zhou
Electrochimica Acta 2017 Volume 235(Volume 235) pp:
Publication Date(Web):1 May 2017
DOI:10.1016/j.electacta.2017.03.100
•Co-Ni based ternary selenides are synthesized by one-step solvothermal method.•CoxNi1-xSe with different Co and Ni ratios have been applied to DSSCs.•CoxNi1-xSe CEs show high electrocatalytic activity due to the synergistic effect.•The PCE of the DSSC with Co0.42Ni0.58Se CE is enhanced by 11.2% compared with Pt CE.One important challenge in dye-sensitized solar cells (DSSCs) is to design and construct low-cost counter electrodes (CEs) with good electrocatalytic performance. In this work, a one-step solvothermal method was used to prepare cobalt-nickel (Co-Ni) based ternary selenides with different Co and Ni ratios. Co-Ni based ternary selenide films were fabricated by simple spray deposition for applications as low-cost and high-performance CEs in DSSCs. Electrochemical measurements demonstrate that the Co-Ni based ternary selenide CEs exhibit high electrocatalytic activity and strong charge-transfer ability for the reduction of I3− due to the synergistic effect between Co and Ni ions in Co-Ni based ternary selenides. In particular, Co0.42Ni0.58Se CE shows the higher electrocatalytic activity than other Co-Ni based ternary selenide CEs and platinum (Pt) CE. Furthermore, the DSSC with Co0.42Ni0.58Se CE exhibits photoelectrical conversion efficiency (PCE) of 6.15%, which is considerably higher than that of the DSSC with Pt CE (5.53%).Co-Ni based ternary selenide counter electrodes show high electrocatalytic activity for the I3− reduction, and the dye-sensitized solar cells with Co0.42Ni0.58Se counter electrode exhibits the highest photoelectrical conversion efficiency.
Co-reporter:Xiuwen Wang;Ying Xie;Buhe Bateer;Yangtao Zhou;Yi Zhang
Nano Research 2016 Volume 9( Issue 10) pp:2862-2874
Publication Date(Web):2016 October
DOI:10.1007/s12274-016-1172-0
The catalytic activity of materials is highly dependent on their composition and surface structure, especially the density of low-coordinated surface atoms. In this work, we have prepared two-dimensional hexagonal FeS with high-energy (001) facets (FeS-HE-001) via a solution-phase chemical method. Nanosheets (NSs) with exposed high-energy planes usually possess better reaction activity, so FeS-HE-001 was used as a counter electrode (CE) material for dye-sensitized solar cells (DSSCs). FeS-HE-001 achieved an average power conversion efficiency (PCE) of 8.88% (with the PCE of champion cells being 9.10%), which was almost 1.15 times higher than that of the Pt-based DSSCs (7.73%) measured in parallel. Cyclic voltammetry and Tafel polarization measurements revealed the excellent electrocatalytic activities of FeS-HE-001 towards the I3–/I– redox reaction. This can be attributed to the promotion of photoelectron transfer, which was measured by electrochemical impedance spectroscopy and scanning Kelvin probe, and the strong I3– adsorption and reduction activities, which were investigated using first-principles calculations. The presence of high-energy (001) facets in the NSs was an important factor for improving the catalytic reduction of I3–. We believe that our method is a promising way for the design and synthesis of advanced CE materials for energy harvesting.
Co-reporter:Xiuwen Wang, Buhe Batter, Ying Xie, Kai Pan, Yongping Liao, Chunmei Lv, Mingxia Li, Siyu Sui and Honggang Fu
Journal of Materials Chemistry A 2015 vol. 3(Issue 31) pp:15905-15912
Publication Date(Web):23 Jun 2015
DOI:10.1039/C5TA02946E
We report the synthesis of highly crystalline, small sized, α-NiS nanocrystal inks for the fabrication of a counter electrode for dye-sensitized solar cells. Monodisperse α-NiS nanocrystals (about 7 nm) are obtained via a noninjection, solution-phase chemical synthesis method. During the growth process of α-NiS nanocrystals, the Ni–oleate complex, which is generated in situ from the reaction of nickel chloride and sodium oleate, is decomposed and acts effectively as a growth source in synthesizing monodisperse nanocrystals. By controlling the reaction temperature, the resultant nanocrystal sizes and crystallinity can be well tuned. Compared to conventionally obtained NiS bulk materials, monodisperse α-NiS nanocrystals possess abundant catalytic reaction sites for dye-sensitized solar cells due to their small particle size and high crystallinity. First-principles calculations have been employed for the first time to investigate the adsorption energy of I3− molecules on the (111) surface of α-NiS with equilibrium shape. DSSCs based on monodisperse α-NiS nanocrystal ink with higher crystallinity display a power conversion efficiency of 7.33%, which is comparable to that based on the Pt cathode (7.53%), but significantly higher than that based on the bulk NiS (4.64%) and relatively low-crystalline α-NiS nanocrystals (6.32%). It can be attributed to more reaction catalytic sites due to the surface effect of small α-NiS nanocrystals, and the highest work function level (5.5 eV) that matched the redox shuttle potential. We believe that our method paves a promising way to design and synthesize advanced counter electrode materials for energy harvesting.
Co-reporter:Yongping Liao, Kai Pan, Qingjiang Pan, Guofeng Wang, Wei Zhou and Honggang Fu
Nanoscale 2015 vol. 7(Issue 5) pp:1623-1626
Publication Date(Web):08 Dec 2014
DOI:10.1039/C4NR06534D
A NiS/Ni3S2 nanorod composite array that directly grows on Ni foil has been used as a counter electrode for dye-sensitized solar cells; these nickel sulfide nanorods exhibit excellent photo-electrical conversion efficiency when compared with conventional noble-metal Pt electrodes.
Co-reporter:Dr. Yongping Liao; Ying Xie; Kai Pan; Guofeng Wang; Qingjiang Pan; Wei Zhou; Lei Wang; Baojiang Jiang ; Honggang Fu
ChemSusChem 2015 Volume 8( Issue 4) pp:726-733
Publication Date(Web):
DOI:10.1002/cssc.201402654
Abstract
Fe3W3C/WC/graphitic carbon (GC) ternary nanojunction hybrids are synthesized through a solid-state pyrolysis process for dye-sensitized solar cells (DSSCs). First-principles calculations have been first employed to investigate the adsorption energy between I3− and Fe3W3C and WC nanoclusters. Scanning Kelvin probe images indicate that the work function changes greatly due to the formation of ternary nanojunctions, which favor fast photoelectron transfer. A photoelectrical conversion efficiency of 7.1 % is achieved based on Fe3W3C/WC/GC hybrid counter electrodes, which is much higher than those of pure GC (5.02 %) and WC/GC hybrids (6.11 %). It has been further revealed that Fe3W3C/WC/GC hybrid counter electrodes exhibit the best catalytic performances according to relevant electrochemical measurements, which can be attributed to fast photoelectron transfer due to the ternary junctions and the addition of Fe3W3C with more catalytic metallic atoms.
Co-reporter:Dr. Xiaohuan Miao; Kai Pan; Guofeng Wang;Dr. Yongping Liao;Dr. Lei Wang;Dr. Wei Zhou;Dr. Baojiang Jiang; Qingjiang Pan ; Guohui Tian
Chemistry - A European Journal 2014 Volume 20( Issue 2) pp:474-482
Publication Date(Web):
DOI:10.1002/chem.201303558
Abstract
With a facile electrophoretic deposition and chemical bath process, CoS nanoparticles have been uniformly dispersed on the surface of the functionalized graphene nanosheets (FGNS). The composite was employed as a counter electrode of dye-sensitized solar cells (DSSCs), which yielded a power conversion efficiency of 5.54 %. It is found that this efficiency is higher than those of DSSCs based on the non-uniform CoS nanoparticles on FGNS (4.45 %) and built on the naked CoS nanoparticles (4.79 %). The achieved efficiency of our cost-effective DSSC is also comparable to that of noble metal Pt-based DSSC (5.90 %). Our studies have revealed that both the exceptional electrical conductivity of the FGNS and the excellent catalytic activity of the CoS nanoparticles improve the conversion efficiency of the uniformly FGNS-CoS composite counter electrode. The electrochemical impedance spectra, cyclic voltammetry, and Tafel polarization have evidenced the best catalytic activity and the fastest electron transport. Additionally, the dispersion condition of CoS nanoparticles on FGNS plays an important role for catalytic reduction of I3−.
Co-reporter:Xiaohuan Miao, Kai Pan, Yongping Liao, Wei Zhou, Qingjiang Pan, Guohui Tian and Guofeng Wang
Journal of Materials Chemistry A 2013 vol. 1(Issue 34) pp:9853-9861
Publication Date(Web):06 Jun 2013
DOI:10.1039/C3TA11625E
TiO2 microspheres with a large surface area, high crystallinity, uniform nanostructure and good light scattering properties were synthesized in an acetone–phenol mixed solvent via a simple solvothermal process. X-ray diffraction patterns and electron microscopy images indicated that the prepared TiO2 microspheres had a highly mesoporous structure and were composed of highly crystalline anatase nanoparticles. By tuning the ratio of the mixed solvent, high-quality TiO2 microspheres were obtained with controllable surface areas of 122–168 m2 g−1. Then, the mesoporous anatase TiO2 microspheres were used as the scattering layer of the photoelectrode, which is expected to produce high efficiency dye-sensitized solar cells (DSSCs). Compared with photoelectrodes with pure TiO2 nanoparticles or mesoporous anatase TiO2 microspheres, DSSCs based on a photoelectrode with a TiO2 nanoparticle underlayer and a microsphere scattering layer yield the highest photoelectrical conversion efficiency of 7.94%. This is because the obtained TiO2 microspheres have a large surface area and exhibit excellent light scattering, allowing for fast interfacial charge transfer, low series resistance, and superior charge collection efficiency. This has been systematically observed by the electrochemical impedance spectroscopy, intensity-modulated photocurrent spectroscopy and intensity-modulated photovoltage spectroscopy.
Co-reporter:Yongping Liao, Kai Pan, Lei Wang, Qingjiang Pan, Wei Zhou, Xiaohuan Miao, Baojiang Jiang, Chungui Tian, Guohui Tian, Guofeng Wang, and Honggang Fu
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 9) pp:3663
Publication Date(Web):April 8, 2013
DOI:10.1021/am4001584
Because of the advantages of both rapid electron transport of graphitic carbon and high catalytic performance of Fe3C nanoparticle, highly crystalline graphitic carbon (GC)/Fe3C nanocomposites have been prepared by a facile solid-state pyrolysis approach and used as counter electrode materials for high-efficiency dye-sensitized solar cells (DSSCs). The content of Fe3C in the composites can be modified by different hydrochloric acid treatment time. In comparison with pure highly crystalline GC, the DSSC based on GC/Fe3C nanocomposite with 13.5 wt % Fe3C content shows higher conversion efficiency (6.04%), which indicates a comparable performance to the Pt-based DSSC (6.4%) as well. Moreover, not only does our DSSCs have comparable performance to that of the Pt-based DSSC (6.4%), but also is more cost-effective as well. To evaluate the chemical catalysis and stability of nanocomposite counter electrodes toward I3– reduction and the interfacial charge transfer properties, GC/Fe3C nanocomposites have been quantitatively characterized by cyclic voltammetry, electrochemical impedance spectra, and Tafel polarization curve. All the results have revealed that the GC/Fe3C nanocomposite counter electrodes can exhibit high catalytic performance and fast interfacial electron transfer, which can be acted as a very promising and high cost-effective materital for DSSCs.Keywords: catalysis; counter electrode; Fe3C; graphitic carbon; interfacial charge transfer;
Co-reporter:Kai Pan, Youzhen Dong, Wei Zhou, Qingjiang Pan, Ying Xie, Tengfeng Xie, Guohui Tian, and Guofeng Wang
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 17) pp:8314
Publication Date(Web):August 19, 2013
DOI:10.1021/am402154k
The TiO2 nanobelt/ZnO nanorod composite photoelectrodes with flower-like and/or grass-like microstructures have been fabricated via a facile solution growth routine, just by controlling the treatment of the TiO2 nanobelt substrate. For the flower-like composite, the ZnO nanorods disperse orientationally on TiO2 nanobelt films, while for the grass-like one, ZnO nanorods grow disorderly like grass on the TiO2 nanobelt film surface. Furthermore, quasi-Fermi energy level changes of both photoelectrodes have been quantitatively characterized by the surface photovoltage based on the Kelvin probe, which clearly reveals the efficiency of photogenerated electron–hole separation. Owing to the decrease of quasi-Fermi energy level, the flower-like TiO2 nanobelt/ZnO nanorod heterogeneous nanostructure presents a high efficiency of photogenerated electron–hole separation. Therefore, the flower-like TiO2 nanobelt/ZnO nanorod heterogeneous nanostructure photoelectrode has achieved a better performance of water splitting compared with the grass-like TiO2 nanobelt/ZnO nanorod one.Keywords: electron−hole separation; heterogeneous nanostructure; quasi-Fermi energy level; surface photovoltage; water splitting;
Co-reporter:Xiaohuan Miao, Kai Pan, Qingjiang Pan, Wei Zhou, Lei Wang, Yongping Liao, Guohui Tian, Guofeng Wang
Electrochimica Acta 2013 Volume 96() pp:155-163
Publication Date(Web):30 April 2013
DOI:10.1016/j.electacta.2013.02.092
Highly crystalline graphene/carbon black composite counter electrodes, possessing advantages of both rapid electron transport of graphene and high surface area of carbon black, have been prepared using a facile approach. Tuning composite content allows for the fabrication of high-efficiency dye-sensitized solar cells (DSSCs) in this work. The ratio of graphene and carbon black at ca. 1:3 in weight has been confirmed optimum for synthesizing the composite counter electrode. By comparison with those made of either highly crystalline graphene or carbon black, the DSSC based on composite counter electrode has higher conversion efficiency. Moreover, not only does our DSSCs have comparable performance to that of the Pt-based DSSC, but is more cost-effective. Additionally, the chemical catalysis and stability of composite counter electrodes toward I3− reduction, and the interfacial charge transfer have been quantitatively investigated by cyclic voltammetry and electrochemical impedance spectra. The results have revealed that the content of graphene and carbon black in composite counter electrodes is very important for fabricating the DSSCs with high catalytic performance and fast interfacial electron transfer.Graphical abstractHighlights► Certain graphene in composite counter electrode (CE) boosted the efficiency of DSSCs. ► Composite CE combined the merits of graphene and carbon black. ► Systematic research showed the importance of the amount of graphene in composite CE. ► Composite counter electrode had excellent electrochemical stability.
Co-reporter:Kai Pan, Youzhen Dong, Wei Zhou, Guofeng Wang, Qingjiang Pan, Yu Yuan, Xiaohuan Miao, Guohui Tian
Electrochimica Acta 2013 Volume 88() pp:263-269
Publication Date(Web):15 January 2013
DOI:10.1016/j.electacta.2012.10.066
The TiO2-B nanobelt (NB)/anatase TiO2 nanoparticle (NP) heterophase nanostructure is fabricated via layer-by-layer assembly. The heterophase nanostructure composition (i.e. the nanobelt-to-nanoparticle ratio) can be tuned conveniently by controlling the experimental conditions of the layer-by-layer assembly. The formation of heterophase junction is good for the separation of photogenerated electrons and holes. So, the heterophase nanostructures have been used to fabricate photoelectrode for high-efficiency dye-sensitized solar cells (DSSCs), which combines the advantages of the rapid electron transport in NBs and the high surface area of NPs. It is found that, with the optimum preparation conditions, DSSCs with heterophase composite photoelectrode show better photoelectric conversion efficiency (7.54%) than that either with the naked NB photoelectrode or the mechanical mixing NB–NP photoelectrode. It is elucidated by the photoelectron-injection drive force and the interfacial electron transport of DSSCs, which are characterized quantitatively, using the surface photovoltage spectra and electrochemical impedance spectra. The DSSC with optimal NB/NP ratio displays the larger photoelectron injection drive force and the fastest interfacial electron transfer.
Co-reporter:Guoliang Zhang, Kai Pan, Wei Zhou, Yang Qu, Qingjing Pan, Baojiang Jiang, Guohui Tian, Guofeng Wang, Ying Xie, Youzhen Dong, Xiaohuan Miao and Chungui Tian
Dalton Transactions 2012 vol. 41(Issue 41) pp:12683-12689
Publication Date(Web):24 Aug 2012
DOI:10.1039/C2DT31046E
The anatase TiO2 pillar (PL)–TiO2 nanoparticle (NP) composite is fabricated via layer-by-layer assembly. The composition of the nanostructures (i.e. the pillar-to-nanoparticle ratio) can be conveniently tuned by controlling the experimental conditions of the layer-by-layer assembly. It has been used to fabricate photoelectrodes for high-efficiency dye-sensitized solar cells (DSSCs), which combine the advantages of the rapid electron transport in PLs with the high surface area of NPs. It was found that, with optimum preparation conditions, DSSCs with the composite photoelectrode show a better photoelectrical conversion efficiency (8.06%) than those with either the naked PL photoelectrode or the mechanically mixed PL–NP photoelectrode. This is explained by the photoelectron injection drive force and the interfacial electron transport of the DSSCs, which are quantitatively characterized using the surface photovoltage spectra and electrochemical impedance spectroscopy measurements. It is evident that the DSSC with the optimal PL/NP ratio displays the largest photoelectron injection drive force and the fastest interfacial electron transfer.
Co-reporter:Xiaohuan Miao, Kai Pan, Yongping Liao, Wei Zhou, Qingjiang Pan, Guohui Tian and Guofeng Wang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 34) pp:NaN9861-9861
Publication Date(Web):2013/06/06
DOI:10.1039/C3TA11625E
TiO2 microspheres with a large surface area, high crystallinity, uniform nanostructure and good light scattering properties were synthesized in an acetone–phenol mixed solvent via a simple solvothermal process. X-ray diffraction patterns and electron microscopy images indicated that the prepared TiO2 microspheres had a highly mesoporous structure and were composed of highly crystalline anatase nanoparticles. By tuning the ratio of the mixed solvent, high-quality TiO2 microspheres were obtained with controllable surface areas of 122–168 m2 g−1. Then, the mesoporous anatase TiO2 microspheres were used as the scattering layer of the photoelectrode, which is expected to produce high efficiency dye-sensitized solar cells (DSSCs). Compared with photoelectrodes with pure TiO2 nanoparticles or mesoporous anatase TiO2 microspheres, DSSCs based on a photoelectrode with a TiO2 nanoparticle underlayer and a microsphere scattering layer yield the highest photoelectrical conversion efficiency of 7.94%. This is because the obtained TiO2 microspheres have a large surface area and exhibit excellent light scattering, allowing for fast interfacial charge transfer, low series resistance, and superior charge collection efficiency. This has been systematically observed by the electrochemical impedance spectroscopy, intensity-modulated photocurrent spectroscopy and intensity-modulated photovoltage spectroscopy.
Co-reporter:Xiuwen Wang, Buhe Batter, Ying Xie, Kai Pan, Yongping Liao, Chunmei Lv, Mingxia Li, Siyu Sui and Honggang Fu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 31) pp:NaN15912-15912
Publication Date(Web):2015/06/23
DOI:10.1039/C5TA02946E
We report the synthesis of highly crystalline, small sized, α-NiS nanocrystal inks for the fabrication of a counter electrode for dye-sensitized solar cells. Monodisperse α-NiS nanocrystals (about 7 nm) are obtained via a noninjection, solution-phase chemical synthesis method. During the growth process of α-NiS nanocrystals, the Ni–oleate complex, which is generated in situ from the reaction of nickel chloride and sodium oleate, is decomposed and acts effectively as a growth source in synthesizing monodisperse nanocrystals. By controlling the reaction temperature, the resultant nanocrystal sizes and crystallinity can be well tuned. Compared to conventionally obtained NiS bulk materials, monodisperse α-NiS nanocrystals possess abundant catalytic reaction sites for dye-sensitized solar cells due to their small particle size and high crystallinity. First-principles calculations have been employed for the first time to investigate the adsorption energy of I3− molecules on the (111) surface of α-NiS with equilibrium shape. DSSCs based on monodisperse α-NiS nanocrystal ink with higher crystallinity display a power conversion efficiency of 7.33%, which is comparable to that based on the Pt cathode (7.53%), but significantly higher than that based on the bulk NiS (4.64%) and relatively low-crystalline α-NiS nanocrystals (6.32%). It can be attributed to more reaction catalytic sites due to the surface effect of small α-NiS nanocrystals, and the highest work function level (5.5 eV) that matched the redox shuttle potential. We believe that our method paves a promising way to design and synthesize advanced counter electrode materials for energy harvesting.
Co-reporter:Guoliang Zhang, Kai Pan, Wei Zhou, Yang Qu, Qingjing Pan, Baojiang Jiang, Guohui Tian, Guofeng Wang, Ying Xie, Youzhen Dong, Xiaohuan Miao and Chungui Tian
Dalton Transactions 2012 - vol. 41(Issue 41) pp:NaN12689-12689
Publication Date(Web):2012/08/24
DOI:10.1039/C2DT31046E
The anatase TiO2 pillar (PL)–TiO2 nanoparticle (NP) composite is fabricated via layer-by-layer assembly. The composition of the nanostructures (i.e. the pillar-to-nanoparticle ratio) can be conveniently tuned by controlling the experimental conditions of the layer-by-layer assembly. It has been used to fabricate photoelectrodes for high-efficiency dye-sensitized solar cells (DSSCs), which combine the advantages of the rapid electron transport in PLs with the high surface area of NPs. It was found that, with optimum preparation conditions, DSSCs with the composite photoelectrode show a better photoelectrical conversion efficiency (8.06%) than those with either the naked PL photoelectrode or the mechanically mixed PL–NP photoelectrode. This is explained by the photoelectron injection drive force and the interfacial electron transport of the DSSCs, which are quantitatively characterized using the surface photovoltage spectra and electrochemical impedance spectroscopy measurements. It is evident that the DSSC with the optimal PL/NP ratio displays the largest photoelectron injection drive force and the fastest interfacial electron transfer.
