Kinetics of hydrogen production from illuminated CdS/Pt/Na2S dispersions

Abstract

The production of hydrogen (H2) upon illumination of transparent CdS/Pt/Na2S dispersions has been studied over the complete life of the catalyst and as a function of the initial concentration of Na2S. Our results indicate that the observed decline in, and eventual cessation of, H2 production results from the depletion of the electron donor (Na2S) and the deactivation of the catalyst (poisoning). Donor depletion dominates when low initial concentrations of donor are used (less than ca. 4 × 10-3 mol dm-3), whereas with higher concentrations catalyst poisoning is the main deactivation pathway. Evidence is presented which suggests that polysulfides are responsible for the deactivation of the cat..