Accelerating electron transfer of NiFe-LDH via Cr-triggered electronic modulation toward a robust OER.

Abstract

The oxygen evolution reaction (OER) is a critical half-reaction in electrochemical energy conversion technology; however, its slow kinetic process limits energy conversion efficiency. Nickel iron layered double hydroxides (NiFe-LDHs) are promising OER electrocatalysts, which face challenges such as insufficient active centers and poor electron transfer ability. In this study, we report successful in situ doping of Cr ions on the surface of NiFe-LDH using a simple one-step hydrothermal method. The addition of Cr induced synergistic lattice and electronic effects, increased the active surface area and exposed more active sites, leading to excellent OER performance with a low overpotential of 219 mV at a current density of 100 mA cm^-2, a Tafel slope of 58.16 mV dec^-1, and long-term stability for 500 h in 1 M KOH. Cr³⁺ doping could adjust the coordination of Ni, Fe and O, optimize the adsorption of intermediates, accelerate electron transfer and enhance OER kinetics. This work provides a new idea for the regulation of the activity of NiFe-LDHs by heterovalent ion doping and offers a reference for low-cost and high-efficiency OER catalysts.