Lewis Acid Driving Asymmetric Interfacial Electron Distribution to Stabilize Active Species for Efficient Neutral Water Oxidation

Neutral oxygen evolution reaction (OER) with unique reactive environments exhibits extremely slow reaction kinetics, posing significant challenges in the design of catalysts. Herein, a built-in electric field between the tungstate (Ni-FeWO4) with adjustable work function and Lewis acid WO3 is elaborately constructed to regulate asymmetric interfacial electron distribution, which promotes electron accumulation of Fe sites in the tungstate. This decelerates the rapid dissolution of Fe under the OER potentials, thereby retaining the active hydroxyl oxide with the optimized OER reaction pathway. Meanwhile, Lewis acid WO3 enhances hydroxyl adsorption near the electrode surface to improve mass transfer. As expected, the optimized Ni-FeWO4@WO3/NF self-supporting electrode achieves a low overpotential of 235 mV at 10 mA cm-2 in neutral media and maintains stable operation for 200 h. Furthermore, the membrane electrode assembly constructed by such self-supporting electrode exhibits robust stability for 250 h during neutral seawater electrolysis. This work deepens the understanding of the reconstruction of OER catalysts in neutral environments and paves the way for development of the energy conversion technologies. A built-in electric field between Ni-FeWO4 and WO3 simultaneously achieves the electron-rich state of the Fe sites in tungstate and improvement of the local reaction environment to suppress Fe leaching and accelerate mass transfer during neutral water oxidation, which endows the membrane electrode assembly constructed of Ni-FeWO4@WO3/NF with low cell voltages and robust stability for neutral seawater electrolysis.image

Automated summary

This study focuses on the design of catalysts for the neutral oxygen evolution reaction (OER). By constructing a built-in electric field to regulate electron distribution, the optimized Ni-FeWO4@WO3/NF self-supporting electrode exhibits low overpotential and stable operation in neutral media.