Visible Light Induced Generation of Hydrogen from H₂S in CdS‐Dispersions, Hole Transfer Catalysis by RuO₂

Illumination of US‐dispersions by visible light in solutions containing H 2 S or sulfide ions leads to efficient generation of hydrogen and sulfur. Very small quantities of RuO 2 deposited on the CdS‐particles improve markedly the quantum yield of H 2 ‐formation for which the optimum value obtained so far is ϕ = 0.35 ± 0.1. The effect of RuO 2 is attributed to catalysis of hole transfer from the valence band of CdS to H 2 S or sulfide in solution.