Iron and oxygen vacancies co-modulated adsorption evolution and lattice oxygen dual-path mechanism for water oxidation

Abstract

Conjointly activating metal and oxygen sites to trigger the adsorbate evolution and lattice oxygen mechanisms coupled path holds promise for balancing activity and stability in oxygen evolution reaction catalysts, yet confronting great challenges. Herein, we develop Fe species and oxygen vacancies co-regulated Ni-(oxy)hydroxide from the deep reconstruction of Fe-Ni2P/NiMoO4 pre-catalyst achieving the adsorbate evolution and lattice oxygen dual-path mechanism. Experimental details and theoretical calculation analysis reveal the enhanced adsorbate evolution mechanism kinetics at the Ni sites via the co-regulation of Fe species and oxygen vacancies, while the Fe incorporation activates the O sites with preferable adsorption free energy for lattice oxygen mechanism intermediates. Benefiting from the dual-path mechanism, the activated catalyst affords an ampere-scale current density of 1.0 A cm-2 at low overpotentials of 274.5 ± 4.2 and 299.1 ± 2.8 mV in alkaline freshwater and seawater, respectively, and maintains seawater electrocatalysis for 500 h in the anion exchange membrane water electrolysis. This work demonstrates a strategy to trigger the coupled mechanism for efficient and stable electrocatalytic water splitting under harsh conditions. Electrocatalysts for oxygen evolution should balance activity and stability. Here, the authors report that co-regulating Fe and oxygen vacancies couples adsorbate evolution with lattice-oxygen mechanisms, delivering ampere-level alkaline freshwater/seawater oxidation with boosted activity and durability.