Interfacial spin-state engineering through lattice-distorted transition metal oxides heterostructure enables low-voltage and durable anion-exchange-membrane water electrolysis

Abstract

Transition metal oxides (TMOs) exhibit electrocatalytic activity intrinsically tied to their electron spin states, yet precise spin-state regulation without sacrificing structural integrity presents a persistent challenge. Here we introduce a hetero-lattice engineering approach to achieve spin-state modulation in TMOs through lattice distortion. We demonstrate a lattice-distorted Co3O4/MoO3 heterostructure (Co-O-Mo|H) that effectively converts low-spin Co3 + [e(g)(0)t(2)(g)(6)] to high-spin Co3+ [e(g)(2)t(2)(g)(4)]. This electronic reconfiguration enables strengthened *OH adsorption while promoting efficient *OOH desorption, resulting in exceptional oxygen evolution reaction performance with a low overpotential of 211 mV at 10 mA cm(-2), outperforming benchmark RuO2 (321 mV). Simultaneously, the engineered Co-O-Mo interface creates highly active hydrogen evolution sites, delivering ultralow overpotentials of 40/151 mV at current densities of 10/100 mA cm(-2), respectively, surpassing commercial Pt/C (52/170 mV). Integrated into an anion-exchange membrane electrolyzer, the Co-O-Mo|H-based system demonstrates exceptional durability (>200 h at 10 mA cm(-2)) and superior performance, achieving low cell voltages of 1.48/1.57 V at 10/100 mA cm(-2), significantly lower than the 1.58 V and 1.68 V required by RuO2 & Vert;20 % Pt/C. These findings establish a new paradigm for spin-state engineering through lattice distortion in transition metal oxides, offering a strategic pathway toward developing economically viable and robust hydrogen production technologies.