Photoelectrochemical conversion of carbon dioxide to methanol and higher alcohols: A chemical carbon sequestration strategy

There has been increasing interest in artificial photosynthetic schemes for converting atmospheric carbon dioxide into a value added fuel. Photoelectrochemical schemes while theoretically attractive for activating the carbon dioxide molecule, operate at excessive overpotentials and thus do not convert actual light energy to chemical energy. Here we describe the efficient and selective conversion of carbon dioxide to methanol at a semiconducting p-GaP electrode using a substituted pyridinium ion catalyst. We find that the reaction can be driven solely with light energy to yield faradaic efficiencies approaching 100% at potentials well below the thermodynamic potential. In addition to methanol, higher order alcohols such as ethanol and isopropanol can be photochemically synthesized by using ring substituted pyridinium catalysts.