Heterostructure formation and chemical modulation of colloidal Au–Co–Fe nanoparticles for alkaline water oxidation

Abstract Heterostructure engineering is an effective strategy for designing high‐performance electrochemical catalysts by enhancing conductivity and inducing charge transfer at the interface. Several studies have been conducted to control the morphology of heterostructured nanoparticles (NPs); however, studies on three‐metal systems are lacking. In this study, we developed a morphology‐controllable synthesis method for three‐metal systems (Au, Co, and Fe) for high‐performance electrochemical catalysts, including Au–CoFe 2 O 4 heterodimers and Au–Co 0.75 Fe 0.25 core–shell NPs. Oxygen evolution reaction (OER) performance measurements revealed that the Au–CoFe 2 O 4 heterodimer NPs possessed superior catalytic activity compared to the Au–Co 0.75 Fe 0.25 core–shell and CoFe 2 O 4 NPs, requiring 297.14 mV of overpotential at a current density of 100 mA/cm 2 . In addition, the heterodimer displays Tafel slope value of 39.93 mV/dec and exhibits no noticeable degradation for a 50 h stability test at a current density of 100 mA/cm 2 . The enhanced catalytic performance of the heterodimer NPs may be attributed to the electronic structure modulation induced by the high electronegativity of Au and the suppression of Fe leaching during the OER. This morphology control provides an effective strategy for designing heterostructured NPs with diverse compositions that can contribute to the design of high‐performance electrochemical catalysts.