H2 production photosensitized by aqueous semiconductor dispersions

Abstract

CdS powder has been shown to photosensitize the reduction of H2O by sacrificial electron donors (cysteine and EDTA). Platinized CdS was found to be 20 times more efficient for H2 production. H2 was also evolved efficiently from aerobic solutions, although concomitant reduction of O2 was observed. The formal quantum efficiency (f.q.e.) for H2 production was 0.04 mol ein–1 at 436 nm and yields of H2 correlated well with the known spectrum of CdS. Other platinized semiconductor powders (Si, CdSe and CuPc) were found to evolve H2 when illuminated in the presence of EDTA, but these systems were less efficient (f.q.e. < 10–3 mol ein–1).