Mapping the Electronic Descriptors of Electrocatalysis: A Systemic DFT Roadmap for Iridium and Cobalt Oxides in HER, OER, and NO3RR

The transition towards sustainable energy paradigms necessitates the rational design of electrocatalysts for water electrolysis and nitrogen cycles. This study investigates iridium (IrO₂, Ir₂O₃) and cobalt (Co₃O₄) oxides using Density Functional Theory (DFT) within the PAW method, employing the PBE functional with Hubbard U and van der Waals corrections. We scrutinize how surface coordination and oxidation states modulate the thermodynamics of the hydrogen evolution (HER), oxygen evolution (OER), and nitrate reduction (NO₃RR) reactions. The analysis identifies IrO₂ surfaces as possessing optimal adsorption energetics for OER intermediates, effectively mitigating theoretical overpotentials. Conversely, the α−Ir₂O₃(0001) facet emerges as a compelling HER candidate due to favorable interfacial charge redistribution. We link experimental electrochemical aging in Co₃O₄ nanoplates to atomistic surface models. Findings reveal that reconstruction-driven shifts in Co²⁺/Co³⁺ stoichiometry optimize the adsorption of ^∗H and ^∗NO₂ species, thereby augmenting ammonia selectivity.