Electrocatalytic CO₂ reduction to formate by a cobalt phosphino-thiolate complex

Electrochemical conversion of CO₂ to value-added products serves as an attractive method to store renewable energy as energy-dense fuels. Selectivity in this type of conversion can be limited, often leading to the formation of side products such as H₂. The activity of a cobalt phosphino-thiolate complex ([Co(triphos)(bdt)]⁺) towards the selective reduction of CO₂ to formate is explored in this report. In the presence of H₂O, selective production of formate (as high as 94%) is observed at overpotentials of 750 mV, displaying negligible current degradation during long-term electrolysis experiments ranging as long as 24 hours. Chemical reduction studies of [Co(triphos)(bdt)]⁺ indicates deligation of the apical phosphine moiety is likely before catalysis. Computational and experimental results suggest a metal-hydride pathway, indicating an ECEC based mechanism.