Screening Transition-Metal-Incorporated\nβ‑AgVO<sub>3</sub> for Augmented Oxygen Reduction Activity

Exploring cost-effective alternatives to Pt-based catalysts\nfor\nthe oxygen reduction reaction (ORR) in fuel cells is crucial for their\nlarge-scale deployment in green energy applications. Silver vanadate\n(AgVO<sub>3</sub>) is a well-studied material for photocatalytic applications.\nHere, we investigate the electrocatalytic ORR activity of the thermodynamically\nstable β phase of AgVO<sub>3</sub> through computational modeling\nbased on DFT. It is found that β-AgVO<sub>3</sub> exhibits weak\ncatalytic activity for the ORR, with vanadium being the preferable\nactive site. Incorporating single atoms of transition metals at surface-level\nvacancies in β-AgVO<sub>3</sub> significantly modifies the ORR\nactivity. We study the scaling of free energy changes for the ORR\nintermediates *OOH, *OH, and *O for various transition metals incorporated,\nwhich leads to an optimal overpotential for the system. The optimal\noverpotential thus obtained is remarkably lower than that of pristine\nβ-AgVO<sub>3</sub>. For the transition metal atoms we consider\nhere, Co-incorporated β-AgVO<sub>3</sub> exhibits the best ORR\ncatalytic activity due to its optimal binding of ORR species to the\nvanadium site. It is also observed that some of the transition metals\nconsidered like Re, Rh, Os, or Mn show weak activity, either due to\nstrong or weak binding. Analysis of the electronic structure of the\nadsorbate–catalyst interface shows a strong correlation between\noptimal activity and evolution of midgap states in β-AgVO<sub>3</sub>, due to transition metal incorporation. Our study concludes\nthat the ORR activity of a stable mixed transition metal oxide like\nβ-AgVO<sub>3</sub> can be enhanced with a minimal loading of\ntransition metals, which could help in developing a novel series of\nORR catalysts.