Bioinspired acetate-mediated proton shuttling toward robust oxygen evolution

Abstract

Persistent proton accumulation from extensive reactant deprotonation during oxygen evolution reaction (OER) induces severe local acidification at electrode-electrolyte interface, accelerating catalyst degradation and performance decay. Employing NiFe layered double hydroxide (NiFe-LDH) as a model, we present a bioinspired strategy wherein Lewis-basic acetate anion (CH₃COO^–, Ac^–) functions as dynamic proton shuttle to regulate interfacial microenvironment (Ac^–-LDH). Ac^– undergoes reversible –COO^–/–COOH cycle upon protonation, promoting efficient proton transfer and reinforcing hydrogen-bond networks that expedite OH^– delivery to LDH surface. Simultaneously, Ac^– lone pairs selectively coordinate with Fe centers in LDH framework, tuning electronic structure and enhancing intrinsic activity. In-situ Raman and infrared spectroscopy capture transient CH₃COOH formation, while differential electrochemical mass spectrometry evidences proton shuttling via CH₃COOD detection. Theoretical calculations reveal that Ac^– coordination stabilizes active site and reduces OER energy barrier. Leveraging this dual functionality, Ac^–-LDH exhibits superior activity with 213 mV overpotential at 10 mA cm^–2 and remarkable durability, maintaining 50 mA cm^–2 for over 1200 h in anion-exchange membrane electrolyzer. This work establishes bioinspired molecular shuttles for interfacial microenvironment engineering as versatile paradigm for developing OER catalysts with high activity and durability.