Effect of substitution doping and surface adsorption of Al atoms on photocatalytic decomposition of water and oxygen from BiVO4 (010) crystal surface br

Using solar photoelectrochemical decomposition of water to produce hydrogen and oxygen is one of themost feasible approaches to obtaining renewable energy. Compared with hydrogen-evolution reaction (HER),the oxygen-evolution reaction (OER) is very complex, there are four sluggish proton-coupled electron transferprocesses. It is critical to improve OER performance. The BiVO4 (010) facet possesses low surface energy,strong visible absorption, and good activity for OER, and is considered as one of the most suitable PECcatalysts. However, its poor electron conductivity, low charge carrier mobility, and high charge recombinationrates significantly limit its practical applications. To achieve highly active OER photocatalysts, we modifyBiVO4 (010) facet by substitutial doping with Al atom and surface adsorption with Al atom. According todensity functional theory calculations, we compare OER performances of these two modified BiVO4 (010) facets.The results show that both approaches can effectively regulate the electronic structure of BiVO4 and then tuneOER activity resulting from the change of the structure. Though Al substitutional doping reduces the band gapof the (010) facet and enhances the visible light absorption, the improvement of OER performance is notsignificant because the doping site is inside and has little influence on the surface active site. Importantly, thesurface adsorption of Al atom is considered as an efficient means to improve the OER activity on BiVO4 (010)facet due to the combined action between surface adsorbed Al and active site Bi atoms. Al adsorbed (010) facetexhibits excellent OER catalytic activity: 1) the induction of localized states and the reduction of band gap areconducive to the electronic transition, optical absorption, thus increasing the electrical conductivity; 2) there islower hole effective mass, and thus effectively enhancing the ability to transfer from anode surface to electrolytesurface, thereby increasing the difference between the effective mass ratio of electron-hole pairs and 1 andeffectively reducing the electron-hole recombination; 3) the nteraction between the active sites and oxygen-containing intermediates is reinforced in the OER process, therefore the potential determining step of OERdecreases effectively. This work provides an important reference for designing efficient and stable two-dimensional semiconductor-based photocatalysts for OER. We believe that it will arouse great interest of theBiVO4 community and motivate numerous experimental researches