Enhancing oxygen evolution reaction performance via Zn/Fe co-doping in a Co₃O₄ nanostructure: mechanistic insights...

The kinetics of the oxygen evolution reaction (OER) of Co₃O₄ in alkaline media can be promoted by a bimetallic co-doping strategy. Herein, we synthesize a Zn/Fe co-doped Co₃O₄ nanostructure (ZnFe-Co₃O₄) to enhance the oxygen evolution reaction performance in alkaline media. The ZnFe-Co₃O₄ electrocatalyst exhibits a low overpotential of 255 mV at 10 mA cm^-2, a Tafel slope of 54 mV dec^-1 in 1.0 M KOH and excellent long-term durability of up to 120 hours at 100 mA cm^-2. X-ray photoelectron spectroscopy (XPS) reveals that Zn occupies octahedral Co³⁺ sites and Fe occupies tetrahedral Co²⁺ sites in the Co₃O₄ lattice. The experimental results together with theory calculations collectively demonstrate that ZnFe-Co₃O₄ follows the lattice oxygen mechanism (LOM) during the OER process. In situ Raman spectroscopy shows that truly active FeOOH/CoOOH species are formed through surface reconstruction during the OER. Furthermore, it is found that the synergistic effects of Zn and Fe doping, which stabilize the Co₃O₄ structure and promote the generation of active (oxy)hydroxide species, are identified as key factors in enhancing the electrocatalytic performance. This work offers a novel concept for enhancing the electrocatalytic activity of electrocatalysts through doping strategies and provides guidance for the rational design of ideal electrocatalysts.