Manipulating the configuration entropy of layered hydroxides toward efficient oxygen evolution reaction for anion exchange membrane electrolyzer

Abstract

Developing a noble metal-free catalyst for sluggish oxygen evolution reaction (OER) is key to materializing polymer electrolyte membrane water electrolyzer for hydrogen production. Nickel-based layered hydroxides (LDH) represent the most promising basic OER catalysts but still suffer from a limited activity. Herein, we rationally manipulate the configuration entropy of Ni-LDH by introducing different Lewis acidity cations to push its activity to an unprecedented level with an overpotential of 203 mV at 10 mA cm⁻². Operando spectroscopy analysis combined with theoretical calculations reveal that the electronic status and redox behavior of active Ni center can be finely optimized by the incorporated cations via bridge bonds between cations and oxygen anions, thus balancing the adsorption energy of oxygen intermediates and accelerating the OER kinetics. We further identify that the valence of active Ni can act as a descriptor to predict the intrinsic OER activity of high-entropy LDH materials. Accordingly, an alkaline anion exchange membrane electrolyzer using a high-entropy FeCoNiMnMo-LDH catalyst can achieve 1 A cm⁻² at a voltage of 1.73 V, and negligible performance degradation over 100 h.