Construction of a cobalt-doped Ni3S2@NiFe-LDH heterojunction with enhanced local electric field for efficient oxygen evolution reaction

Abstract

Alkaline oxygen evolution reaction (OER), involving a four-electron transfer process, is characterized by high overpotential and extremely sluggish reaction kinetics, posing a significant challenge for catalyst design. Herein, a strategy is proposed to modulate the electronic structure of electrocatalysts by constructing a cobalt-doped Ni₃S₂@NiFe-LDH (Co-Ni₃S₂@NiFe-LDH) hierarchical hollow heterojunction with enhanced local electric field (ELEF). The ELEF in the heterojunction induces band bending of the components, expediting electron transfer and accelerating OER kinetics. Furthermore, the hierarchical hollow structure offers a large specific surface area that ensures full exposure of adsorption and active sites. Benefiting from these synergetic advantages, Co-Ni₃S₂@NiFe-LDH shows remarkable performance and stability with a low overpotential of only 217 mV at 50 mA cm⁻². Density functional theory (DFT) calculations further confirm that the ELEF can optimize the adsorption energy of intermediate reaction species, reduce reaction energy barriers, and modulate the d-band center of active sites, thereby improving the inherent catalytic activity.