Sub-square-meter level γ-Ni(Fe)OOH-dominating electrocatalyst enabling self-adaptive mass transfer for industrial alkaline water electrolysis.

Abstract

Mass transfer is crucial to sustaining the kinetics of alkaline electrolysis under high current densities. Although dynamic electrocatalyst restructuring during the oxygen evolution reaction governs the formation of active sites, how such restructuring affects mass transfer remains unclear. Herein, a scalable oxidant-induced corrosion strategy yields sub-square-meter level NiFeOxSy/nickel mesh (NM) pre-catalyst that undergoes rapid electrochemical desulfurization in-situ to form active γ-Ni(Fe)OOH/NM. A transparent anion exchange membrane water electrolysis visualization system revealed a self-reconstruction process mediating rapid bubble release. The resulting intensified interfacial microconvective disturbances facilitated timely OH- replenishment, enabling the γ-Ni(Fe)OOH/NM interface to maintain relatively high alkalinity. Enhanced mass transfer kinetics achieved an optimal balance between the density of accessible active sites and the efficiency of mass transfer, establishing a self-adaptive mass transfer mechanism. Simultaneously optimizing intrinsic activity synergistically enhanced the overall electrocatalytic performance. Accordingly, γ-Ni(Fe)OOH/NM remained stable for 1000 h at 1.0 A/cm2 and even after undergoing 100 startup/shutdown cycles (1200 h). Further, the γ-Ni(Fe)OOH/NM-based electrolyzer required 2.10 V to achieve 2.0 A/cm2 at 60 ℃ with <8.5% voltage decay over 1600 h at 1.0 A/cm2. Employing the reconstruction as a deliberate mass-transfer-engineering strategy, our work will advance the design of robust catalysts toward industrial-scale electrolysis.

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