Rational design of electrocatalysts for simultaneously promoting bulk charge separation and surface charge transfer in solar water splitting photoelectrodes†,Journal of Materials Chemistry A

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Rational design of electrocatalysts for simultaneously promoting bulk charge separation and surface charge transfer in solar water splitting photoelectrodes†
Journal of Materials Chemistry A ( IF 10.7 ) Pub Date : 2018-01-03 00:00:00 , DOI: 10.1039/c7ta10361a
Yingfei Hu _{1,

2,

3,

4,

5} , Yangqing Wu _{4,

5,

6,

7} , Jianyong Feng _{1,

2,

3,

4,

5} , Huiting Huang _{1,

2,

3,

4,

5} , Chunchen Zhang _{1,

2,

3,

4,

5} , Qinfeng Qian _{1,

2,

3,

4,

5} , Tao Fang _{1,

2,

3,

4,

5} , Jun Xu _{4,

5,

6,

7} , Peng Wang _{1,

2,

3,

4,

5} , Zhaosheng Li _{1,

2,

3,

4,

5} , Zhigang Zou _{1,

2,

3,

4,

5}

Affiliation

For a photoanode, a large overpotential for water oxidation, which limits the solar-to-hydrogen efficiency, may be caused by slow water oxidation kinetics and the recombination of photo-induced electrons and holes. Herein, taking flat and thin BiVO₄ photoanodes as an example, the composite AgO_x/NiO_x electrocatalyst was found to promote not only the water oxidation kinetics, but also the bulk charge separation. As a result, the surface charge injection efficiency (η_inj) and the bulk charge separation efficiency (η_sep) of BiVO₄ photoanodes were improved by the composite AgO_x/NiO_x electrocatalyst. Photo-assisted electrochemical impedance spectroscopy (EIS) was employed to illustrate the significantly reduced surface charge transfer resistance of the BiVO₄/AgO_x/NiO_x sample at the interface between the photoanode surface and the electrolyte. Analysis of the surface potential changes obtained from photo-assisted Kelvin probe force microscopy (KPFM) revealed that the surface photovoltage (SPV) of the BiVO₄/AgO_x/NiO_x photoanode is higher than those of BiVO₄/AgO_x and BiVO₄/NiO_x, representing its large band bending region for bulk charge separation. The open circuit photovoltage (OCP) measurements also demonstrated the superior charge separation ability of the BiVO₄/AgO_x/NiO_x photoanode. The possible working mechanism is that one component of the composite AgO_x/NiO_x electrocatalyst may stabilize the high valence states of the other metal ions, which is beneficial for the formation of water oxidation active sites and the extension of the band bending region.

中文翻译：

合理设计电催化剂，以同时促进太阳能分水光电极中的大量电荷分离和表面电荷转移†

对于光阳极而言，水氧化的过大电势限制了太阳能转化效率，这可能是由于水氧化动力学缓慢以及光生电子和空穴的复合引起的。在此，以扁平且薄的BiVO _4光阳极为例，发现复合AgO _x / NiO _x电催化剂不仅促进水氧化动力学，而且促进整体电荷分离。其结果是，表面的电荷注入效率（η _INJ），松电荷分离效率（η_月）BiVO的_4个光阳极被提高了复合的AgO _X /氧化镍_X电催化剂。使用光辅助电化学阻抗谱（EIS）来说明在光阳极表面和电解质之间的界面处BiVO ₄ / AgO _x / NiO _x样品的表面电荷转移电阻显着降低。通过光辅助开尔文探针力显微镜（KPFM）获得的表面电势变化的分析表明，BiVO ₄ / AgO _x / NiO _x光电阳极的表面光电压（SPV）高于BiVO ₄ / AgO _x和BiVO ₄的表面光电压。/氧化镍_X，代表用于大批电荷分离的大弯曲带区域。开路光电压（OCP）测量也证明了BiVO ₄ / AgO _x / NiO _x光电阳极具有优异的电荷分离能力。可能的工作机制是复合AgO _x / NiO _x电催化剂的一种组分可以稳定其他金属离子的高价态，这对形成水氧化活性位点和扩展带弯曲区是有益的。

更新日期：2018-01-03

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