Interfacial C-M-O bond engineering in CoMoO₄/graphdiyne heterostructures for high-current-density anion exchange membrane water electrolysis

Efficient AEMWE based green hydrogen production demands oxygen evolution electrocatalysts with fast kinetics and durable stability at high current densities. Yet in alkaline media, the slow turnover of oxygenated intermediates and the degradation of active sites under oxidizing potentials are two major hurdles. Herein, we report a three-dimensional self-supported CoMoO₄/graphdiyne (GDY) heterostructure with engineered interfacial C-M-O bonds for highly efficient oxygen evolution reaction (OER). The interfacial chemical coupling generates new intrinsic active sites and increases their density, while promoting water adsorption, OH- accumulation, and charge transport, thereby optimizing the adsorption and conversion of OER intermediates. As a result, the catalyst exhibits excellent OER activity in alkaline electrolyte, requiring an overpotential of only 189 mV to reach 10 mA cm⁻². In a practical AEMWE cell, it achieves 1000 mA cm⁻² at 1.76 V and 80 °C, with stable operation for over 200 h. Density functional theory calculations further show that GDY incorporation not only switches the OER route from the AEM to the LOM with a substantially reduced rate-determining barrier, but also, via stable C-Co-O and C-Mo-O interfacial bonds, induces coordination expansion and d-band downshift that expose more active sites and thus enhance OER kinetics. This work demonstrates that interfacial chemical bond engineering effectively modulates the local electronic structure and reaction energetics, providing a viable strategy for high-performance alkaline water electrolysis.