Catalyzed Reactions at Illuminated Semiconductor Interfaces

Many desirable minority carrier chemical redox processes are too slow to compete with e— — h ₊ recombination at illuminated semiconductor/liquid electrolyte junction interfaces. Reductions of H₂O to H₂ or CO₂to compounds having C-H bonds are too slow to compete with e — h _{+ recombination} at illuminated /?-type semiconductors, for example. Approaches to improve the rate of the desired processes involving surface modification techniques are described. Photoanodes are plagued by the additional problem of oxidative decomposition under illumination with >Eg illumination. The photo-oxidation of Cl~, Br“, and H₂O is considered to illustrate the concepts involved. Proof of concept experiments establish that catalysis can be effective in dramatically improving direct solar fuel production; efficiencies of > 10% have been demonstrated.