A new hybrid photocatalytic system based on a mixed-phase cadmium sulfide matrix composed of Q-sized and hexagonal CdS interlinked with elemental platinum deposits has been developed. This unusual hybrid composite catalyst is effective for the photochemical reduction of gaseous hydrogen from water with visible light irradiation.

Orange crystallites of hex-CdS were synthesized by the thermal treatment of commercial grade cubic-phase CdS at 800 ^oC under a flowing-nitrogen atmosphere for one hour. Platinum was photodeposited on the hex-CdS surfaces before sol-gel synthesized Q-CdS deposition to form a hybrid Q-CdS/Pto/hex-CdS composite. TEM images show Q-CdS islands on Pt/hex-CdS surfaces with an average radius of 6.5 nm.

The average rates of hydrogen production for Pt/Q-CdS/hex-CdS and Q-CdS/Pt/hex-CdS composites were 537 micromol/g/hr and 668 micromole/g/hr, respectively, under visible light irradiation at wavelengths > 420 nm in the presence of reduced sulfur electron donors at pH 14.