An investigation on the role of W doping in BiVO4 photoanodes used for solar water splitting
An investigation on the role of W doping in BiVO4 photoanodes used for solar water splitting
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W掺杂在用于太阳能水分解的BiVO4光阳极中的作用研究
DOI：
10.1039/c8cp01316k
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发表时间：
2018
影响因子：
3.3
通讯作者：
Chen Zhong
中科院分区：
文献类型：
--
作者：
Zhao Xin;Hu Jun;Chen Shi;Chen Zhong
在用于分解水的光电化学电池中，N型掺杂被广泛用于提高光阳极的性能。然而，关于表面催化过程中掺杂对催化活性的影响，人们知之甚少。本文以BiVO4为例，从实验和理论两个方面研究了掺杂对表面催化性能的影响。为了能够进行公正的比较，我们制备了掺钨和不掺钨的平面BiVO4薄膜。结果表明，W掺杂对薄膜的形貌、结晶度和光吸收没有明显影响，但显著提高了薄膜的光电流。这种增强是由两个重要因素造成的：更好的电荷分离效率和更好的表面电荷转移效率。电化学分析表明，W掺杂降低了表面电荷转移电阻，形成了活性表面态，促进了电荷转移。理论分析表明，W掺杂激活了V原子，使其成为反应中心。此外，水裂解过程中所涉及的吸附能和吸附物种(OHads、OADs和OOHads)之间的距离变得更有利于表面电荷转移。目前的研究对W掺杂在BiVO4中的作用，特别是在表面催化过程中的作用提供了深入的了解。
n-Type doping has been widely employed to enhance the performance of a photoanode in a photoelectrochemical cell used for water splitting. However, little is known about how doping affects the catalytic activity during surface catalysis. Herein, we took BiVO4 as an example to investigate the effect of doping on surface catalysis from both experimental and theoretical perspectives. To enable an impartial comparison, we have prepared planar BiVO4 thin films with and without W doping. It was found that W doping had no obvious effect on the morphology, crystallinity, and light absorption of the film; however, the photocurrent was significantly enhanced upon W doping. This enhancement is contributed by two important factors: better charge separation efficiency and improved surface charge transfer efficiency. Electrochemical analysis reveals that W doping lowers the surface charge transfer resistance and forms active surface states, facilitating charge transfer. Theoretical analysis shows that W doping activates the V atoms to be reactive sites. Moreover, the adsorption energies and distance between adsorption species (OHads, Oads, and OOHads) involved in the water splitting process become more favorable for surface charge transfer. The current study provides an insight into the roles of W doping in BiVO4, especially during surface catalysis.