The Enhanced Local Co Concentration for Efficient Co2 Electrolysis Towards C2 Products on Tandem Active Sites

• A tandem catalytic strategy for CO 2 activation and local CO enhancement was developed. • The enhanced CO environment was confirmed to be the key of C2 products generation. • In-situ RRDE technique was developed to monitor CO intermediate during eCO 2 RR. Electrochemical reduction of CO 2 to C2 products on Cu-based catalysts provides a promising approach for controlling the global carbon balance and restoring renewable surplus electricity. The enhanced CO 2 adsorption and CO local concentration are beneficial for CO 2 conversion and C2 intermediates formation, promoting the progress of CO 2 utilization. Here, we report a bimetallic MOF-derived Co 3 O 4 -CuO x /C (M-CuCo/C) catalyst constructed with Co 3 O 4 and CuO x sites wrapped in the carbon skeleton, achieving efficient CO 2 activation and C2 generation under low overpotential. The optimized M-CuCo/C catalyst (Cu/Co ratio of 1:2) exhibits a total current density of 19.28 mA/cm 2 at -1.05 (V vs. RHE), which is 8.60 times than that on MOF-derived CuO x /C (M-Cu/C). The highest C2 faradic efficiency (FE) reaches 79.2% (-0.75 V vs. RHE), accompany with a C2 production rate of 275.6 μmol/(g·h). The special nanorods-like morphology assembled by dual sites significantly increases electrochemical surface area and electron transmission rate during eCO 2 RR. The local CO intermediates under real-time electrochemical environment are monitored via rotation ring disk electrode (RRDE) techniques. Combined with in situ infrared measurements and DFT studies, it’s demonstrated that CO 2 could be efficiently converted to CO under low overpotential on Co 3 O 4 sites, forming local CO-enriched environment around neighboring CuO x sites and further accelerating the process of C2 formation.