Pattengale B, Huang J
Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, USA.
Phys Chem Chem Phys. 2017 Mar 1;19(9):6831-6837. doi: 10.1039/c6cp08564d.
Monoclinic-scheelite BiVO has been widely studied as a promising oxygen evolution reaction (OER) catalyst in artificial photosynthesis. Though significant progress to improve or augment its catalysis performance has been made, fundamental understanding of its relatively poor performance as a bare material is lacking. In this paper, we report the correlation of the surface structure and trap states with charge separation efficiency and OER performance of bare BiVO photoanodes via varying the sample thickness. Using X-ray absorption spectroscopy (XAS), we observed a more compacted, symmetric Bi center in the surface state. Using transient absorption (TA) spectroscopy, we show that the structural properties of the surface lead to shallow and deep hole trap states and electron trapping that occurs at the surface of the material. Despite more severe carrier trapping on the surface, our OER measurements demonstrate that a significant bulk structure is required for light absorption but is only beneficial until the carrier mobility becomes the limiting factor in photoelectrochemical cell studies.
单斜白钨矿BiVO作为人工光合作用中一种很有前景的析氧反应（OER）催化剂已得到广泛研究。尽管在改善或增强其催化性能方面已取得显著进展，但对于其作为裸材料时相对较差性能的基本认识仍很缺乏。在本文中，我们通过改变样品厚度，报道了裸BiVO光阳极的表面结构和陷阱态与电荷分离效率及OER性能之间的相关性。利用X射线吸收光谱（XAS），我们观察到表面态中有一个更紧凑、对称的Bi中心。利用瞬态吸收（TA）光谱，我们表明表面的结构特性导致了浅和深的空穴陷阱态以及在材料表面发生的电子俘获。尽管表面上有更严重的载流子俘获，但我们的OER测量表明，光吸收需要一个显著的体相结构，并且在光化学电池研究中，直到载流子迁移率成为限制因素之前，体相结构才是有益的。
