Synthesis of BiVO4 nanoparticles with tunable oxygen vacancy level: the phenomena and mechanism for their enhanced photocatalytic performance

Abstract The development of efficient visible-light-driven photocatalysts is a great challenge due to their high charge recombination rate. Herein, BiVO4 nanoparticles with controllable oxygen vacancy levels were synthesized via a hydrothermal approach, followed by post-annealing treatment in an oxygen-deficient environment. The oxygen vacancy level within BiVO4 nanoparticles could be modulated by varying the annealing temperature between 300 and 400 oC in an Ar gas environment. Different oxygen vacancy levels could effectively change the bandgap of BiVO4, resulting in changes in photocatalytic efficiency. The BiVO4 nanoparticles with the optimal oxygen vacancy level showed a photocatalytic efficiency of 98%, which was 38% increased over pure BiVO4. A series of characterizations, including impedance spectra, transient photocurrent response, and electron spin resonance spectra, revealed that the increased photocatalytic efficiency was mainly ascribed to the efficient suppression of electron/hole recombination.