Defect-designed Mo-doped BiVO4 photoanode for efficient photoelectrochemical degradation of phenol

Abstract

The monoclinic scheelite BiVO4 has impressive properties such as a narrow energy band gap, exceptional stability, and extended absorption in visible light, making it a suitable photoanode. Nevertheless, the BiVO4 material encounters challenges such as the high recombination rate of photogenerated electron-hole pairs and poor photoelectron conductivity, which limits photocatalytic activity. To address this problem, we developed Mo-doped BiVO4 films on FTO substrates for photoelectrocatalytic degradation of phenol. When exposed to visible light, the Mo-BiVO4 film attained a 70% degradation of phenol in 120 min with a 1.2 V vs. Ag/AgCl bias—a 3.7 times improvement from pristine BiVO4. Mo-doping facilitates better migration and separation of electron-hole pairs and increases the concentration of photogenerated carriers, leading to an upward shift of the valence band potential direction, and an improvement in oxidation capacity. Furthermore, density-functional theory (DFT) calculations were used to explain how Mo-doping with BiVO4 improves the adsorption energy to phenol degradation intermediates, emphasizing its effectiveness in promoting phenol degradation. Therefore, with the inclusion of DFT calculations, this work provides a more comprehensive understanding of the mechanism underlying the enhancement of photocatalytic activity by Mo-doped BiVO4, which is crucial information for the further development of effective and efficient photoanodes.