Mo-doping and CoOx loading over BiVO4 photoanode for enhancing performance of H2O2 synthesis and in-situ organic pollutant degradation

Abstract

The combination of photoelectrochemical water oxidation hydrogen peroxide (H₂O₂) on the anode and hydrogen evolution on the cathode increase the value of the water splitting process. However, the sluggish water oxidation kinetics and slow carrier transport limit the generation of H₂O₂. In this study, to promote H₂O₂ production, the surface of a Mo doped BiVO₄ photoanode was modified with CoO_x co-catalyst. The resulting CoO_x/Mo-BiVO₄ photoanode generates H₂O₂ at a rate of 0.39 μmol min⁻¹ cm⁻² with a selectivity of 76.9% at 1.7 V_RHE. The experimental results indicate that CoO_x decorated on Mo-BiVO₄ kinetically favors the H₂O₂ production via reduced band bending, while inhibiting H₂O₂ decomposition. According to density functional theory calculations, the loading of CoO_x enhances the efficiency of the Mo-BiVO₄ photoanode in generating H₂O₂. Moreover, the in-situ generated H₂O₂ through CoO_x/Mo-BiVO₄ was applied to the degradation of tetracycline in aqueous solution, finding that CoO_x/Mo-BiVO₄ exhibits the best performance among the catalysts evaluated. This work demonstrates that the CoO_x co-catalyst can effectively facilitate the water oxidation to H₂O₂, opening a way for its application in situ water remediation.