Sulfur doping improves the weak adsorption on BiVO4 (0 1 0) facet to enhance the oxygen evolution performance

Abstract

Photoelectrochemical (PEC) water splitting is one of the most effective methods for sustainable hydrogen production, but the undesirable binding between the oxygen-containing intermediates and active sites limits the performance of the oxygen evolution reaction (OER) of BiVO4 (0 1 0) crystal. Our density functional theory (DFT) calculations show that non-metallic sulfur doping can effectively improve this weak interaction on the surface by tuning the electronic structure of BiVO4. The introduction of the S atom greatly improves the photoelectric properties. The band gap reduces from 2.22 eV to 1.51 eV, favoring visible light absorption and electronic conductivity. The effective mass of the electrons reduces from 1.55 me to 0.76 me, indicating carrier mobility increases. The effective mass ratio reduces from 1.04 to 0.54, meaning the photogenerated electron-hole recombination is suppressed. More importantly, S doping-induced charge rearrangement promotes more charges distributed around the active site Bi atom, greatly improving the interaction between the oxygen-containing intermediate and the surface during the OER process, and therefore the OER overpotential reduces to 0.34 V. These interesting findings may provide an important reference for the design of high-efficiency two-dimensional semiconductor photocatalysts for the OER.