TUNGSTEN DISULFIDE: A NOVEL HYDROGEN EVOLUTION CATALYST FOR WATER DECOMPOSITION.

Silica-supported tungsten disulfide was prepared by the reaction of WO//3/SiO//2 with H//2S at 300 degree C. The WS//2 hexagonal structure was confirmed by X-ray diffraction analysis. AES and XPS studies show the existence of residual tungsten oxides in addition to WS//2. Hydrogen evolution properties of WS//2/SiO//2 were determined by catalytic and photocatalytic (in the presence of fluorescein or CdS as sensitizers) tests and by electrochemical measurements. These were compared with silica-supported platinum. Although a graphite electrode immersed in a Pt/SiO//2 slurry evolved hydrogen at a more positive applied potential than in a WS//2/SiO//2 slurry, silica-supported tungsten disulfide was more active and stable than Pt/SiO//2 for catalytic hydrogen production both in the dark and under visible light illumination (with cadmium sulfide as a sensitizer).