Interfacial Engineering of a ZnO/NiO Heterostructure Anode on Nickel Foam for Selective Electrochemical Methane Oxidation

Electrochemical conversion offers a promising pathway for the selective partial oxidation of methane under mild conditions, but precisely controlling the selective activation of C–H bonds to directly generate high-value oxygenates such as methanol remains a challenge. This paper reports a ZnO/NiO heterostructure anode constructed on a three-dimensional nickel foam substrate using a urea-assisted in situ growth strategy to enhance the electrochemical oxidation performance of methane. The optimized Zn–U/NF-6h electrode selectively generates methanol, ethanol, and acetone while effectively suppressing the deep oxidation of CO2. The methanol generation rate reaches approximately 1.1 × 103 μmol g_cat–1 h–1, with a maximum methanol selectivity of 68%. Systematic characterization results show that the three-dimensional porous structure of the nickel foam facilitates the high dispersion of ZnO, thereby constructing a tightly contacted ZnO/NiO heterointerface, while the introduction of urea further promotes the formation and stabilization of this heterointerface. The constructed ZnO/NiO heterostructure significantly improved interfacial charge transport efficiency, thereby effectively promoting the electrochemical conversion of methane. Furthermore, this heterostructure electrode exhibited stable operation for over 24 h during continuous electrolysis. The optimized sample exhibits the lowest charge transfer resistance and the highest electrochemical surface area, which correlates well with its superior methanol production rate. This study demonstrates that combining heterostructure engineering with rational electrode structure design is a crucial strategy for driving high-value electrochemical conversion of methane.