The reduction of CO2 to high-energy, value-added chemical intermediates such as formic acid/formate is a key step in utilizing CO2 for renewable production of fuels and chemicals. To accomplish such transformations, iridium pincer dihydride complexes have been developed to catalyze the electrocatalytic two-electron reduction of CO2 to formate. Ir PCP-type pincer complexes are able to reduce CO2 to formate electrocatalytically both in non-aqueous media and in water with high efficiency and selectivity. Formate is the only reduced carbon product, produced in 93% Faradaic yield with a small amount of H2 but no formation of CO. The high selectivity for formate production over H2 originates from the aqueous stability of Ir dihydride species, the active species for reduction of CO2. As a further pursuit of reducing CO2 with high efficiency, an iridium pincer dihydride catalyst was immobilized on carbon nanotube-functionalized gas diffusion electrodes by using a non-covalent binding strategy. High turnover numbers (~200,000) and turnover frequencies (~15 s–1) were observed in aqueous solutions saturated in CO2 with added HCO3– which is enabled by the novel electrode architecture. The developed Ir pincer complexes can be used as viable tools for photoelectrochemical CO2 reduction using solar energy, and integration of these catalysts into Dye Sensitized Photoelectrosynthesis Cells (DSPEC) in conjunction with molecular chromophores is currently underway.

Electrocatalytic reduction of CO2 to formate using iridium pincer complexes

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.