Electrocatalytic reduction is a promising strategy for CO 2 utilization, while the conversion of CO 2 to C 2 products usually suffers from the low selectivity. Herein, we report several high-performance Cu-OCN catalysts for electroreduction CO 2 -to-C 2 H 4 , which are prepared through the in-situ calcination of nanocube Cu 2 O and urea. The highest C 2 H 4 faradaic efficiency from Cu-OCN-10 reaches 55.97%, much higher than that from the pristine CuO counterpart (38.31%), with a partial current density of −12.83 mA cm −2 . Catalyst characterizations and first-principles density functional theory calculations reveal that the superior performance of CuO-OCN is attributed to the introduced nitrogen (N) species and oxygen (O)-vacancies. With the assistance of N species and O-vacancies, the adsorption of CO 2 on Cu-OCN-10 is thermodynamically favorable with the absorption energy of −0.69 eV. Meanwhile, the activation of CO 2 is promoted and the generated *CO intermediate on Cu-OCN-10 is stable, whose release needs to overcome an energy of 2.26 eV, thereby enhancing the C C coupling to produce C 2 H 4 . In general, the synergistic effects of N species and O-vacancies in Cu-OCN catalysts facilitate CO 2 electroreduction to C 2 H 4 .
Multi-phase interfaces are promising for surmounting the energy barriers of electrochemical CO2 reduction involving multiple electron transfer steps, but challenges still remain in constructing interfacial micro-structures and unraveling their dynamic changes and working mechanism. Herein, highly active Ag/Cu/Cu2O heterostructures are in situ electrochemically restructured from Ag-incorporating HKUST-1, a Cu-based metal–organic framework (MOF), and accomplish efficient CO2-to-C2H4 conversion with a high faradaic efficiency (57.2% at −1.3 V vs. RHE) and satisfactory stability in flow cells, performing among the best of recently reported MOFs and their derivatives. The combination of in/ex situ characterizations and theoretical calculations reveals that Ag plays a crucial role in stabilizing Cu(I) and increasing the CO surface coverage, while the active Cu/Cu2O interfaces significantly reduce the energy barrier of C–C coupling toward the boosted ethylene production. This work not only proves MOFs as feasible precursors to derive efficient electrocatalysts on site, but also provides in-depth understanding on the working interfaces at an atomic level.
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