Issue Date: April 14, 2014
Solar Energy Splits Hydrogen Sulfide
A new process uses sunlight to split hydrogen sulfide into its components, hydrogen and sulfur (Angew. Chem. Int. Ed. 2014, DOI: 10.1002/anie.201400571). Ubiquitous and toxic, H2S is produced during industrial reactions and in the environment. Currently, industry uses the Claus process to partially oxidize H2S to elemental sulfur and water. But a much more attractive prospect would be to generate H2 and S, turning waste into valuable commodities. Chemists in search of effective, efficient reactions to split H2S have tried thermal, thermochemical, and electrochemical approaches, with varying degrees of success. A reaction using solar energy would be preferred, however. In a proof-of-concept experiment, an international team led by Can Li of China’s Dalian Institute of Chemical Physics and Lianzhou Wang of the University of Queensland, Australia, converted H2S to sulfur and protons using redox couples (I−/I3− or Fe2+/Fe3+). Then, a photoelectrode made of functionalized silicon reduced the protons to form H2. Challenges still remain to make the process industrially useful, including separating the elemental sulfur from water and purifying it.
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