Molecular Modification of Single Cobalt Sites Boosts the Catalytic Activity of CO2 Electroreduction into CO.

Abstract

Electroreduction of CO2 into carbonaceous fuels or industrial chemicals using renewable energy sources is an ideal way to promote global carbon recycling. Thus, it is of great importance to develop highly selective, efficient, and stable catalysts. Herein, we prepared cobalt single atoms (Co SAs) coordinated with phthalocyanine (Co SAs-Pc). The anchoring of phthalocyanine with Co sites enabled electron transfer from Co sites to CO2 effectively via the π-conjugated system, resulting in high catalytic performance of CO2 electroreduction into CO. During the process of CO2 electroreduction, the Faradaic efficiency (FE) of Co SAs-Pc for CO was as high as 94.8 %. Meanwhile, the partial current density of Co SAs-Pc for CO was -11.3 mA cm-2 at -0.8 V versus the reversible hydrogen electrode (vs RHE), 18.83 and 2.86 times greater than those of Co SAs (-0.60 mA cm-2 ) and commercial Co phthalocyanine (-3.95 mA cm-2 ), respectively. In an H-cell system operating at -0.8 V vs RHE over 10 h, the current density and FE for CO of Co SAs-Pc dropped by 3.2 % and 2.5 %. A mechanistic study revealed that the promoted catalytic performance of Co SAs-Pc could be attributed to the accelerated reaction kinetics and facilitated CO2 activation.