Halogen doping induces differential bonding reconstruction at Ni-Fe dual sites in NiFe-LDH for efficient and durable oxygen evolution.

Abstract

Achieving site-selective electronic modulation at bimetallic active centers represents a fundamental challenge in designing efficient electrocatalysts for the oxygen evolution reaction (OER) in water electrolysis. In this work, a halogen (F, Cl, Br) doping strategy is employed to systematically regulate the bonding properties of bimetallic sites in NiFe layered double hydroxide (NiFe-LDH), revealing the quantitative structure-activity relationship between anion electronegativity and site-specific bonding reconstruction. Density functional theory (DFT) calculations reveal that F doping induces bond-selective modulation effect at the bimetallic sites. Specifically, it strengthens the antibonding character of NiO bonds to facilitate dynamic active phase reconstruction, while converting FeO bonds to a weakly bonding state that preserves structural integrity. This dual-site modulation effectively resolves the intrinsic coordination dilemma between Ni and Fe sites. Benefiting from the F--induced ultrathin mesoporous nanosheet arrays and the bond-selective modulation, F-NiFe-LDH achieves a current density of 500 mA cm-2 at an overpotential of only 268 mV, along with a low Tafel slope of 31.1 mV dec-1, and excellent stability over 240 h. This work provides both experimental evidence and theoretical guidance for the rational design of high-performance bimetallic electrocatalysts through anion engineering.