(Invited) Strategies in Colloidal Catalysis for Generation of Solar Fuels

Abstract

This talk will describe two separate strategies to use colloidal semiconductor nanocrystals to photocatalytically produce (i) the fuel intermediate CO from the abundant feedstock CO2, and (ii) H2 from protons within a hydrogel with pH-dependent structure. CO2 reduction is accomplished with record turnover in pure water with a combination of colloidal CuInS2 nanocrystals and a cobalt porphyrin electrocatalyst. The nanocrystals are decorated with partially protonated amine-terminated ligands, which not only provide a means of electrostatic self-assembly with the negatively charge porphyrin, but also allow pre-activation of the CO2 through formation of carbamic acid. In a separate system based on cadmium chalcogenide nanorods, the yield of proton reduction is non-monotonically dependent on the pH of the hydrogel with a large spike near the pKa of the exposed amine groups within the gel.