Evaluating the Reactivity of BiVO<sub>4</sub> Surfaces for Efficient Electrocatalytic H<sub>2</sub>O<sub>2</sub> Production: A Combined Experimental and Computational Study
Ashish Nadar, S. S. Gupta, Yusuf Kar, Sharan Shetty, Alexander P. van Bavel, Deepa Khushalani
Abstract
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.