Electronic Structure\nof Monoclinic BiVO₄

Abstract

A comprehensive approach to understanding\nthe electronic structure\nof monoclinic scheelite bismuth vanadate (<i>ms</i>-BiVO₄), including both valence band (VB) and conduction band (CB)\norbital character, is presented. Density functional theory (DFT) calculations\nare directly compared to experimental data obtained via X-ray absorption\nspectroscopy (XAS), X-ray emission spectroscopy, resonant inelastic\nX-ray spectroscopy (RIXS), and X-ray photoelectron spectroscopy to\nprovide a complete portrait of the total and partial density of states\n(DOS) near the bandgap. DFT calculations are presented to confirm\nthe VB maximum and CB minimum are comprised primarily of O 2p and\nV 3d orbitals, respectively. Predicted triplet d-manifold splitting\nof V 3d CB states, arising from lone pair-induced lattice distortions,\nis quantified by V L- and O K-edge XAS. Furthermore, the partial contributions\nto the total DOS within both the CB and VB, determined by RIXS, are\nfound to be in excellent agreement with DFT calculations. Energy levels\nare placed relative to the vacuum level by photoemission spectroscopy,\nwhich provides a measure of the work function and electron affinity\nof the investigated BiVO₄ thin film. The implications of\nthe fundamental electronic structure of <i>ms</i>-BiVO₄ on its photocatalytic behavior, as well as considerations\nfor improvements by substitutional incorporation of additional elements,\nare discussed.