MOF-derived Cu@Cu2O heterogeneous electrocatalyst with moderate intermediates adsorption for highly selective reduction of CO2 to methanol

Abstract

Schematic representation of CH 3 OH production via CO 2 electrochemical reduction over Cu@Cu 2 O heterogeneous electrocatalyst. • MOF-derived Cu@Cu 2 O heterogeneous electrocatalyst was proposed to promote CO 2 RR. • Cu 0 and Cu + active sites contributed to synergistic catalytic effect. • The intermediate products CO*, COOH*, and CHO* were detected on in-situ ATR-FTIR. • Cu@Cu 2 O-400 °C electrocatalyst exhibited a peak FE CH3OH of 45% at −0.7 V vs RHE. To improve Faradaic efficiency (FE) of CO 2 reduction reaction (CO 2 RR) to methanol over Cu-based complex electrocatalysts, a novel MOF-derived Cu@Cu 2 O heterogeneous electrocatalyst with moderate intermediates adsorption was proposed for highly selective reduction of CO 2 to methanol. XRD and HRTEM confirmed the presence of a distinct heterogeneous interface between Cu and Cu 2 O, while XPS verified the existence of Cu 0 /Cu + and OH on catalyst surfaces. Cu 0 /Cu + with a moderate CO* binding energy and OH which favored H* adsorption were conducive to hydrogenation reduction of CO 2 to methanol. The intermediate products CO*, COOH*, and CHO* were detected on in-situ electrochemical ATR-FTIR spectroscopy. The most favorable reduction route of CO 2 to methanol was as follows: CO 2 → COOH* → CO*+H 2 O → CHO* → CH 2 O* → CH 2 OH* → CH 3 OH. The FE of electrochemical CO 2 reduction to methanol over Cu@Cu 2 O-400 °C electrocatalyst was ≥35% at −0.6 ∼ −1.0 V (vs. RHE). The Cu@Cu 2 O-400 °C electrocatalyst exhibited a peak FE CH3OH of 45% at −0.7 V, which was attributed to synergistic effect between Cu 0 and Cu + active sites.