Photoreduction of CO2 using p-terphenyl as a photosensitizer and a tertiary amine as a sacrificial electron donor is efficiently catalyzed by cobalt macrocycles in methanolic acetonitrile solutions. Studies of the mechanism of CO2 reduction in the catalytic system using CoIIHMD2+ (HMD = 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene) have been carried out using continuous and flash photolysis techniques. The transient spectra reveal the formation of p-terphenyl radical anion, the CoIHMD+ complex, the 5-coordinate [CoIHMD-CO2]+ complex, and the six coordinate [S-CoIIIHMD-(CO2 2-)]+ complex (S = solvent) in the catalytic system. The importance of changes in the CoII/I reduction potential and the geometry around the Co center was studied by the use of several different complexes.
ASJC Scopus subject areas
- Energy Engineering and Power Technology
- Fuel Technology
- Nuclear Energy and Engineering
- Renewable Energy, Sustainability and the Environment