High-Coverage Nanometric MO_x (M = Ir, Rh) Clusters Anchored on Spinel Co₃O₄ Matrix With Amorphous/Crystalline Heterostructure Harness Efficient Water Electrolysis

Abstract

Architecting nanometric cluster electrocatalysts with high density of active atoms offers a valuable avenue to simultaneously augment atomic utilization efficiency and catalytic stability. Herein, nanometric IrO_x and RhO_x clusters are anchored onto the spinel Co₃O₄ framework (CoMO_x, M = Ir, Rh), yielding a unique amorphous/crystalline heterostructure. The optimized CoMO_x catalysts with precise-tuning calcination treatment present a favorable electrocatalytic activity with low OER (CoIrO_x: 235 mV @ 10 mA cm⁻²) and HER (CoRhO_x: 157 mV @ 10 mA cm⁻²) overpotentials. Operando electrochemical impedance spectroscopy in combination with density functional theory calculations reveal that the strong interfacial electronic coupling between nanometric clusters and the spinel Co₃O₄ matrix enhances the electron density near the Fermi level and upshifts the d-band center, thereby facilitating hydrogen release during the HER and lowering the OER rate-determining step (OH*→O*) free energy.

Keywords

amorphous/crystalline heterostructure / charge transfer / nanometric cluster / water electrolysis

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2026 The Author(s). Energy & Environmental Materials published by John Wiley & Sons Australia, Ltd on behalf of Zhengzhou University.