Tuning Surface Coordination Environment of Ni3N by Fluorine Modification for Efficient Methanol Electrooxidation Assisted Hydrogen Evolution

Abstract

Replacing the kinetically sluggish oxygen evolution reaction with the thermodynamically favorable methanol oxidation reaction (MOR) represents a promising strategy for energy-efficient hydrogen production. However, optimizing electrocatalytic performance in the coupled hydrogen evolution reaction (HER) and MOR requires precise regulation of the electrochemical coordination environment and a fundamental understanding of activity origins, posing a significant challenge. Here, a scalable strategy is developed that harnesses the high electronegativity of fluorine (F) to tailor the coordination environment of Ni₃N, enhancing HER kinetics. Concurrently, adsorbed F ions induce rapid and extensive self-reconstruction of the Ni₃N surface during MOR by dynamically modulating interfacial ion concentrations (OH⁻ and Ni species). This reconstruction enhances catalytic activity and enables the selective oxidation of methanol to formate via a sequential pathway, involving primary O-H bond activation followed by subsequent C-H bond cleavage at Ni active sites. Consequently, F₁₀-Ni₃N demonstrates exceptional bifunctional performance, delivering 2.02 V and remarkable stability (600 h) for MOR-coupled hydrogen production in a membrane electrode assembly-based flow electrolyzer at an industrially relevant current density of 200 mA cm⁻². This work establishes a dual-regulation paradigm for electrocatalysts, offering mechanistic insights into surface reconstruction and a rational design framework for next-generation energy conversion systems.