Orbital Coupling Engineering through P-Block Metal Doping in NiFe Layered Double Hydroxides for Enhanced Anion-Exchange Membrane Water Electrolysis

The oxygen evolution reaction (OER) remains a major kinetic bottleneck in anodic water splitting because of sluggish adsorption and desorption kinetics of O-containing intermediates. Optimizing the adsorption strength of various O-containing intermediates in accordance with the Sabatier principle involves the precise tuning of the active-site electronic structure. Herein, we explore a p-block metal-assisted synergism regulation strategy in NiFe layered double hydroxides (LDHs) by introducing group-13 elements (Al, Ga, In) as dopants. Among various doped LDHs, In-doped NiFe-LDH shows the highest OER activity by demanding an overpotential value of 298 mV at 10 mA/cm2 along with enhanced intrinsic turnover frequency and long-term stability. X-ray absorption spectroscopy (XAS) reveals that In3+ preferentially occupies the Fe coordination sites, while valence-band X-ray photoelectron spectroscopy (VB-XPS) confirms enhanced electronic coupling in the Ni–O–In framework. Density functional theory (DFT) additionally suggests that the In 5p orbitals strongly hybridize with the O 2p and Ni 3d states, establishing a Ni3d-O2p-In5p electronic interaction that regulates the Ni electronic structure and optimizes the adsorption energies of O-containing intermediates. The resulting d-p-p orbital hybridization offers an efficient pathway for charge delocalization and strengthens the M–O covalency, thereby accelerating the OER kinetics. This study elucidates the structure–activity relationship and identifies p-block metal-induced orbital hybridization as an effective strategy for developing high-performance oxygen evolution electrocatalysts, offering an alternative to conventional transition-metal modification approaches.