Cu2O@ZIF-8 hybrid catalysts with optimized electronic structures tailored by interfacial interactions for efficient electrocatalytic CO2 reduction†
Abstract
The electrocatalytic reduction of CO2 into value-added products is a promising and sustainable strategy to mitigate greenhouse gas emissions while generating valuable chemical feedstocks. However, achieving high selectivity, efficiency, and stability remains a significant challenge. In this work, a hybrid material consisting of zeolite-imidazolate framework-8 (ZIF-8) and Cu2O is synthesized for efficient electrocatalytic reduction reaction of CO2 (CO2RR) into carbon monoxide (CO) and methane (CH4). The hybrid catalyst combines the high surface area and porous structure of ZIF-8 with the excellent catalytic properties of Cu2O, yielding exceptional dual-product selectivity. Cu2O@ZIF-8 achieves a high current density of 40 mA cm−2 and a remarkable FECO of 84.7% at −1.0 V and FECH4 of 78.8% at −1.2 V with a large current density of 63.6 mA cm−2, respectively. The hybrid structure also demonstrates exceptional stability, retaining its activity and morphology over 20 hours of continuous operation. Density Functional Theory (DFT) calculations reveal that the incorporation of Cu2O reduces the bandgap of ZIF-8 and enhances the electron density of sp2 carbon sites, enabling efficient charge transfer and stabilization of key intermediates like COOH*. Moreover, the electron-rich sp2 carbon atoms help stabilize the COOH* intermediate after combining Cu2O with ZIF-8, enhancing the interaction between Zn–N and Cu–N sites. This work provides critical insights into the design of MOF-based hybrid catalysts, offering a simple yet effective approach for advancing CO2 reduction technologies.