Molecular proton-reduction catalysis at silicon semiconductor surfaces

Abstract

Driving catalysis at semiconductor:liq. junctions with light enables the efficient conversion and storage of solar energy in chem. fuels. Hydrogen evolution from water is one possible path to fuel, as there are known heterogeneous and homogeneous catalysts for proton redn. Homogeneous catalysts show the greatest promise for clarifying both (1) key mechanistic aspects of the hydrogen-evolution reaction at the surface and (2) energetic considerations of the semiconductor band structure. Along this line, we are studying a family of rhodium complexes as model catalysts for hydrogen evolution at semiconductor:liq. junctions. Both diffusional and silicon surface-attached systems have been developed, and will be compared. This approach has yielded new information concerning the ambiguities of homogeneous vs. Heterogeneous catalysis, as well as the possible catalytic mechanism(s) of the surface-attached species.