Tungsten disulfide: a novel hydrogen evolution catalyst for water decomposition

Silica-supported tungsten disulfide was prepared by the reaction of WO/sub 3//SiO/sub 2/ with H/sub 2/S at 300/sup 0/C. The WS/sub 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/sub 2/. Hydrogen evolution properties of WS/sub 2//SiO/sub 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/sub 2/ slurry evolved hydrogen at a more positive applied potential than in a WS/sub 2//SiO/sub 2/ slurry, silica-supported tungsten disulfide was more active and stable than Pt/SiO/sub 2/ for catalytic hydrogen production both in the dark and under visible light illumination (with cadmium sulfide as a sensitizer).