Tailoring the OER activity of Co3O4(001) by Mn and V-doping: insights from DFT+U calculations

Designing efficient electrocatalysts for clean energy conversion requires atomic-scale insight into the relationship between targeted surface modifications and catalytic performance. Using density functional calculations with an on-site Hubbard U term (DFT+U), we investigate the effect of Mn and V doping on the performance of Co3O4(001) as an anode material for the oxygen evolution reaction (OER). Our results show that Mn, which is preferentially incorporated at a surface octahedral site at both the B- and A-terminated Co3O4(001) surfaces, has a detrimental effect on the OER efficiency. V also prefers a surface octahedral site at the B-layer termination, acquiring a 5+ oxidation state and reducing the overpotential (η) of a Cooct reaction site from 0.48 V to 0.43 V. At the pristine A-termination, the tetrahedral surface Co reaction site has a lower OER activity (0.74 V) than the octahedral Co site (0.55 V). This trend is reversed with V-doping, where V favors incorporation at a subsurface octahedral site, adopting a 4+ oxidation state, resulting in the lowest overpotential of 0.18 V for a Cotet reaction site. Taking into account implicit solvation increases the overpotential for both undoped and Mn-doped surfaces, whereas it marginally decreases the overpotential for the V-doped A-layer termination. The deprotonation of *OH to *O constitutes the potential-determining step for all investigated surface reaction sites, thereby positioning them on the right leg of the volcano plot, while η of the Cotet reaction site at the V-doped A-layer lies beyond the top of the volcano. The enhancement in catalytic activity of the V-doped A-layer is largely attributed to the modification of the surface Cooct oxidation state from Co3+ (IS) to Co2+ due to the subsurface incorporation of V4+. This substantially reduces the binding energy of *OH and thereby the PDS by 0.56 eV. These insights demonstrate how selective doping can be used as a promising strategy to tailor catalyst’s performance.