Designing Polyoxotungstate-Supported Dual-Atom Catalysts for Water Splitting and Metal–Air Batteries: A DFT Investigation

Abstract

The development of efficient electrocatalysts for overall water splitting and metal–air batteries remains challenging due to the need to simultaneously optimize active-site stability, intermediate adsorption energetics, and catalytic performance across multiple electrochemical reactions. In this study, density functional theory (DFT) calculations are performed to investigate homonuclear dual-transition-metal catalysts supported on a Lindqvist-type polyoxotungstate (POT) cluster. A series of 23 TM₂/POT systems is systematically evaluated to establish structure–property-activity relationships linking dual-metal coordination, catalyst stability, electronic structure, and reaction energetics toward the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). V₂/POT exhibits near-thermoneutral hydrogen adsorption (ΔG_H* = 0.05 eV), indicating favorable HER thermodynamics. For oxygen electrocatalysis, Au₂/POT and Ni₂/POT show promising bifunctional OER and ORR performance, with calculated overpotentials of 0.55 and 0.59 V for OER and 0.56 and 0.65 V for ORR, respectively, together with favorable formation energies of −0.42 eV (Au₂/POT) and −1.41 eV (Ni₂/POT) and dissolution potentials of 1.64 V (Au₂/POT) and 0.44 V (Ni₂/POT). The activity trends are interpreted through d-band center analysis, charge redistribution, and projected density of states (PDOS). Overall, dual-metal incorporation within the POT framework modulates local coordination and charge redistribution, thereby tuning adsorption energetics and establishing structure–property-activity relationships for the rational design of electrocatalysts for overall water splitting and metal–air batteries.