Photoelectrochemical OER activity by employing BiVO4 with manganese oxide co-catalysts

Abstract

The structure–activity relationship in the electrochemical OER has been studied widely, but aspects of the photoelectrochemical (PEC) O₂ evolution activity with different manganese oxides are not fully explored. In the present study different manganese oxides (MnO₂, MnO_x (a mixture of Mn³⁺ and Mn⁴⁺ ions), Mn₂O₃, and Mn₃O₄) have been electrodeposited onto the BiVO₄ photoanode as co-catalysts for PEC water splitting. We find that BiVO₄–MnO_x shows the lowest onset potential of 0.33 V vs. RHE and the highest activity among the manganese oxides. Annealing at different temperatures results in the improvement of the OER kinetics at the interface with some detrimental effect on the activity of BiVO₄. Such a study may lead to useful changes in the fabrication of semiconductor thin film photoelectrodes useful for PEC water splitting.