Tandem ZnO/Cu‐MOF Heterostructures: Boosting Selective CO ₂ Electroreduction to C ₁ and Beyond

A simple strategy for the conjugation of copper‐1,4‐benzene dicarboxylic (CuBDC) MOF with zinc oxide (ZnO) matrix for the fabrication of CuBDC/ZnO is presented—a tandem electrocatalyst with excellent electrochemical stability and electrocatalytic performance toward selective electroreduction of CO 2 (ERCO 2 ). The tandem action and easy mass transport in mesostructured CuBDC/ZnO are demonstrated to facilitate efficient, facile, and selective production of methane, ethylene, and ethane from ERCO 2 . Conjugation with ZnO results in a sevenfold increase in specific activity of CuBDC MOF for ethylene evolution, along with a twofold decrease in its H 2 evolution activity. The exceptional electronic, mass transfer, and positive synergism among the different components in CuBDC/ZnO composite are demonstrated to endow it with excellent electrocatalytic performance (overall Faradaic efficiency (FE) of 77.5% for hydrocarbons, with FEC 1 = 50.9% and FEC 2 = 26.6%), lower Tafel slopes, enhanced exchange current density, appreciably low resistance to charge transfer, and electrochemical stability towards ERCO 2 (>14 h). The presented investigations suggest that the enhanced electronic conductivity, the open metal centers, the mixed valence states (Cu 1+ and Cu 2+ ), and tandem catalytic sites (Cu and Zn) for asymmetric *CO adsorption, hydrogenation, and CO bond dissociation endow the CuBDC/ZnO with excellent activity toward ERCO 2 for production of hydrocarbons.