Low-Cost Water-Splitting Photocatalyst

Cadmium sulfide doped with a small amount of molybdenum disulfide serves as an efficient photocatalyst for the water-splitting reaction under visible light, according to researchers at the Dalian Institute of Chemical Physics in China (J. Am. Chem. Soc., DOI: 10.1021/ja8007825). The study may lead to new low-cost methods for tapping the sun's power, for example by using solar radiation to generate hydrogen from water. Precious metals and their oxides are commonly added to semiconductor photocatalysts to enhance the materials' catalytic activity. Rather than using those types of expensive materials, Xu Zong, Can Li, and coworkers developed synthesis methods to boost cadmium sulfide's activity by doping the semiconductor with low-cost sulfides. The group finds that pure MoS₂ is inactive for water splitting and that pure CdS evolves hydrogen from water but only at low rates. By using a wet chemical procedure to load CdS with just 0.2% by weight of MoS₂, the group increased CdS's activity by a factor of 36. Unlike the wet chemical products, mechanical mixtures of MoS₂ and CdS generate little hydrogen from water, the team reports.