Cationic vacancy enriched NiFe layered double hydroxide with Co doping for ultra-stable ampere-level alkaline water oxidation

NiFe-layered double hydroxides (NiFe-LDHs) are among the most promising earth-abundant electrocatalysts for the oxygen evolution reaction (OER) in alkaline media. However, their practical application is hindered by intrinsic activity limitations and poor stability, primarily due to the asymmetric adsorption of oxygen intermediates. To overcome this, the binding strength must be synergistically tuned to a moderate level to optimize catalytic performance. Here, we engineered NiFeCoCr LDH through Co doping to enhance electrical conductivity and controlled Cr leaching to introduce cationic vacancies for modulating intermediate binding strength in NiFe LDH. X-ray absorption near-edge structure and extended X-ray absorption fine structure analyses reveal that NiFe-LDH with Co doping and Cr vacancies modulates the Ni oxidation state and local coordination environment, leading to a balanced electronic structure and enhanced structural complexity around the Ni sites. Additionally, these vacancies can trap OH⁻/H₂O species, which can serve as a reservoir for OH⁻ transfer, facilitating the rapid formation of OER intermediates and enhancing catalytic performance at high current densities. As a result, V_Cr-NiFeCo LDH achieves 1.6 A cm⁻² current density at 1.7 V vs. RHE while maintaining stable operation for over 1000 h at 500 mA cm⁻². Density functional theory (DFT) calculations validate the synergistic effects of Co doping and Cr-induced vacancies on intermediate binding energies and improved OER kinetics. Overall, this work presents a rational design strategy to simultaneously enhance the activity and durability of NiFe-based OER catalysts for their application in high-performance alkaline water electrolysis.