Highly Selective CO2 Electroreduction to C2H4 Using a Metal–Organic Framework with Dual Active Sites

Conversion from CO 2 to C 2 H 4 is important for the development of energy and the environment, but the high energy barrier of hydrogenation of the *CO intermediate and C–C coupling step tend to result in C 1 compounds as the main product and thus restrict the generation of C 2 H 4 . Here, we report a metal–organic framework (denoted as PcCu-Cu-O ), composed of 2,3,9,10,16,17,23,24-octahydroxyphthalo-cyaninato)copper(II) (PcCu-(OH) 8 ) ligands and the square-planar CuO 4 nodes, as the electrocatalyst for CO 2 to C 2 H 4 . Compared with the discrete molecular copper-phthalocyanine (Faradaic efficiency (FE) of C 2 H 4 = 25%), PcCu-Cu-O exhibits much higher performance for electrocatalytic reduction of CO 2 to C 2 H 4 with a FE of 50(1)% and a current density of 7.3 mA cm –2 at the potential of −1.2 V vs RHE in 0.1 M KHCO 3 solution, representing the best performance reported to date. In-situ infrared spectroscopy and control experiments suggested that the enhanced electrochemical performance may be ascribed to the synergistic effect between the CuPc unit and the CuO 4 unit, namely the CO on the CO-producing site (CuO 4 site) can efficiently migrate and dimerize with the *CO intermediate adsorbed on the C 2 H 4 -producing site (CuPc), giving a lower C–C dimerization energy barrier.