Ag_3XO_4(X=P,As,V)电子结构及光催化性质的第一性原理计算

基于密度泛函理论的第一性原理对Ag_3XO_4(X=P,As,V)电子结构及光催化性质进行了对比研究。与Ag_3XO_4相比,Ag_3VO_4较好的光催化稳定性主要源于其结构中Ag-O间较强的作用力增加了对Ag+的控制,而Ag_3VO_4弱的光催化活性与其导带底中存在d轨道成份以及较低的价带边势(2.335 V,vs NHE)有关;对Ag_3AsO_4而言,其优于Ag_3XO_4光催化活性的原因基于三个方面:(1)由高分散Ags-Ags杂化轨道构成的导带底能带;(2)窄的带隙(1.91 e V);(3)宽的可见光响应范围以及高的光吸收系数。此外,Ag_3XO_4(X=P,As,V)均为间接带隙半导体光催化材料,其中,Ag_3VO_4有用于分解水制氢研究的可能;上述计算结果与实验结果吻合。

First-Principles Study on the Electronic and Photocatalytic Properties of Ag3XO4 (X = P,As, V)

In this study, the electronic structures and photocatalytic properties of Ag₃XO₄ (X = P, As, V) were investigated using the first principles based on the density functional theory. In comparison to Ag₃PO₄, Ag₃VO₄ shows better photocatalytic stability, mainly due to the enhanced Ag―O bonds and improved Ag ion stability, but poorer photocatalytic activity in the visible light region mainly due to the presence of d orbital character at the conduction band minimum (CBM) and lower valence band maximum (VBM) potentials (2.335 V, vs NHE). Ag₃AsO₄ shows photocatalytic activity superior to Ag₃PO₄, which may be attributed to the following reasons: (1) the highly dispersive band structure of the CBM resulting fromAg s-Ag s hybridization, (2) a smaller band gap of 1.91 eV, (3) the broader absorption range and higher absorption capacity of visible light. Moreover, our theoretical results demonstrate that though Ag₃XO₄ (X = P, As, V) species act as indirect band gap photocatalytic semiconductors, only Ag₃VO₄ is a potential candidate for the photocatalytic hydrogen generation from water. The calculated results mentioned above are in good agreement with experimental results.