Achieving Efficient and Stable Oxygen Evolution With Borate‐Intercalated NiFe‐LDH in Anion Exchange Membrane Water Electrolyzers

ABSTRACT The nickel‐iron layered double hydroxides (NiFe‐LDH) have garnered extensive attention as promising anodic catalysts for the oxygen evolution reaction (OER) in alkaline media, but also suffering from high overpotential. In this study, we reveal that the borate‐intercalation contributes to the adjustment of electron cloud density of nickel and promoted the transition from Ni II ‐O to more active Ni III ‐O, which enhances OER kinetics. The turnover frequency (TOF) results indicate improved intrinsic catalytic activity. At the same time, the resultant crystalline‐amorphous heterostructure provides an improved electrochemical active area, benefiting to the exposure of the active sites. Consequently, the BO 3 3− /NiFe‐LDH achieved a high activity and delivered a low overpotential of 234 mV at 10 mA cm − 2 and low Tafel slope of 47.3 mV dec −1 , superior to that of NiFe‐LDH ( η 10 = 251 mV, Tafel slope 115 mV dec −1 ). Notably, the AEMWE with BO 3 3− /NiFe‐LDH anode catalyst layer exhibited a current density of 3.5 A cm − 2 at 2 V, which was far higher than that of NiFe‐LDH. A long‐term stability over 1000 h at industrial current density of 500 mA cm −2 was recorded with low degradation rate of 0.157 mV h −1 . This work presents new avenues for regulating LDH intercalation, ultimately enhancing OER performance in AEMWE applications.