Coordinate activation in heterogeneous carbon dioxide reduction on Co-based molecular catalysts

As CO 2 coordination with the metal sites in molecular catalysts represents an effective means to CO 2 activation, it is important to develop molecular catalysts with high ability of CO 2 coordination to enhance their catalytic performance in CO 2 electroreduction. Herein, we investigated the coordinate activation of CO 2 with Co-based molecular catalysts by manipulating their ligand structures. During CO 2 electroreduction, the current density of Co-salophen for CO was −16.0 mA cm −2 at −0.75 V versus reversible hydrogen electrode ( vs RHE), which was 7.6 times of that (−2.1 mA cm −2 ) of Co-salen. In addition, the Faradaic efficiency (FE) of Co-salophen for CO reached 75 % at −0.70 V vs RHE, whereas the FE of Co-salen for CO production was 19 %. In-situ experiments and mechanistic studies revealed that both Co-salophen and Co-salen adopted a side-on coordination of CO 2 with Co sites. Moreover, the bonding between CO 2 and Co sites was strengthened in Co-salophen, resulting in the enhanced activity of Co-salophen.