CO2-to-CO conversion with over 10% efficiency using earth abundant system in a single-compartment reactor with oxygen tolerant Mn complex catalyst.

ABSTRACT

The direct conversion of CO2 in flue gas to value-added chemicals is a potentially important cost-effective solar-driven CO2 reduction technology. The present work demonstrates the solar-powered conversion of CO2 to CO with greater than 10% efficiency using a Mn complex cathode and an Fe-Ni anode in a single-compartment reactor without an ion exchange membrane in conjunction with a Si solar cell. Reactors separated by ion exchange membranes are typically used to prevent any effects of oxygen generated by the counter electrode. However, the present Mn complex catalyst maintained its activity even in the presence of 15% O2. Operando surface-enhanced Raman spectroscopy established that the present Mn catalyst preferentially reacted with CO2 without adsorbing O2. This unique characteristic enabled solar-driven CO2 reduction using a single-compartment reactor. In contrast, catalytic metals such as Ag tend to lose activity in such systems as a consequence of reaction with oxygen produced at the anode.