Evaluating the Reactivity of BiVO₄ Surfaces for Efficient Electrocatalytic H₂O₂ Production: A Combined Experimental and Computational Study

Three BiVO₄ morphologies, varying in the surface ratios corresponding to high and low index planes, (−121) and (040), respectively, were synthesized and directly grown on a conducting substrate. These three different substrates were evaluated for electrochemical water oxidation reaction to preferentially form hydrogen peroxide at the anode. Experimental results show that the prevalence of high-index plane (−121) contributes favourably for producing H₂O₂, against O₂ formation. Furthermore, density functional theory studies show that the adsorption behavior of HCO₃ species on these high-index surfaces lends to a possible explanation that accounts for better stability of the evolving H₂O₂ molecules. The HCO₃ species adsorbed on the low-index surface are shown to contribute to a pathway that leads to the decomposition of the H₂O₂ molecule. This observation is purported to contribute to a lower H₂O₂ generation efficiency for low index facets. These important differences on the two surfaces, brought about by the structure of the surface-adsorbed HCO₃ species, highlight the mechanistic coadsorption route which is important for contributing to the overall knowledge that both the catalyst surface structure and binding of the HCO₃ species in unison aid in either stabilization or degradation of H₂O₂.