2D Copper Tetrahydroxyquinone Conductive Metal-Organic Framework for Selective CO2 Electrocatalysis at Low Overpotentials

Metal-organic frameworks (MOFs) are promising materials for electrocatalysis; however, lack of electrical conductivity in the majority of existing MOFs limits their effective utilization in the field. Herein, an excellent catalytic activity of a 2D copper (Cu)-based conductive MOF, copper tetrahydroxyquinone (Cu-THQ), is reported for aqueous CO2 reduction reaction (CO2RR) at low overpotentials. It is revealed that Cu-THQ nanoflakes (NFs) with an average lateral size of 140 nm exhibit a negligible overpotential of 16 mV for the activation of this reaction, a high current density of approximate to 173 mA cm(-2) at -0.45 V versus RHE, an average Faradaic efficiency (F.E.) of approximate to 91% toward CO production, and a remarkable turnover frequency as high as approximate to 20.82 s(-1). In the low overpotential range, the obtained CO formation current density is more than 35 and 25 times higher compared to state-of-the-art MOF and MOF-derived catalysts, respectively. The operando Cu K-edge X-ray absorption near edge spectroscopy and density functional theory calculations reveal the existence of reduced Cu (Cu+) during CO2RR which reversibly returns to Cu2+ after the reaction. The outstanding CO2 catalytic functionality of conductive MOFs (c-MOFs) can open a way toward high-energy-density electrochemical systems.