Dicopper(I) Sites Confined in a Single Metal–Organic Layer Boosting the Electroreduction of CO2 to CH4 in a Neutral Electrolyte

It is challenging and important to achieve high performance for an electrochemical CO 2 reduction reaction (eCO 2 RR) to yield CH 4 under neutral conditions. So far, most of the reported active sites for eCO 2 RR to yield CH 4 are single metal sites; the performances are far below the commercial requirements. Herein, we reported a nanosheet metal–organic layer in single-layer, namely, Cu 2 (obpy) 2 ( Cuobpy-SL, Hobpy = 1 H -2,2′bipyridinyl-6-one), possessing dicopper(I) sites for eCO 2 RR to yield CH 4 in a neutral aqueous solution. Detailed examination of Cuobpy-SL revealed high performance for CH 4 production with a faradic efficiency of 82(1)% and a current density of ∼90 mA cm –2 at −1.4 V vs . reversible hydrogen electrode (RHE). No obvious degradation was observed over 100 h of continuous operation, representing a remarkable performance to date. Mechanism studies showed that compared with the conventional single-copper sites and completely exposed dicopper(I) sites, the dicopper(I) sites in the confined space formed by the molecular stacking have a strong affinity to key C 1 intermediates such as *CO, *CHO, and *CH 2 O to facilitate the CH 4 production, yet inhibiting C–C coupling.