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).