Hydrogen has great potential as an energy source but production of hydrogen through water splitting is expensive, largely due to the use of platinum as a catalyst in the process.
Recently, we covered research in Switzerland where a molybdenum-sulfide catalyst took platinum's place. This morning, however, the latest news in water splitting comes from North Carolina State University, where researchers are working with a thin film of molybdenum disulfide (MoS2) to replace platinum.
While the thin film catalyst is not as efficient as platinum, it is relatively inexpensive. The senior author of the research and assistant professor of materials science and engineering at NCSU, Dr. Linyou Cao describes the results:
"We found that the thickness of the thin film is very important. A thin film consisting of a single layer of atoms was the most efficient, with every additional layer of atoms making the catalytic performance approximately five times worse."
The importance of the thin film's thickness was a surprising discovery to researchers, according to the report from NCSU, since it has long been thought that catalysis generally takes place at the edges of a material. Since thin films have little edge, thin films were conventionally considered catalytically inactive.
The researchers' current production of hydrogen is powered by electricity, but the development of a solar-powered water-splitting device using the same MoS2 catalyst is under way.
The paper, "Layer-dependent Electrocatalysis of MoS2 for Hydrogen Evolution," is published online in Nano Letters.