Researchers at Oregon State University have created a new class of materials that can use light to produce hydrogen from water, offering a potentially cleaner way to convert solar energy into fuel. The work was led by Kyriakos Stylianou of the OSU College of Science. His team developed a photocatalyst capable of producing hydrogen quickly and efficiently.
Hydrogen is widely used in fuel cells for vehicles, as well as in the production of ammonia, metal refining, and plastics manufacturing. Using Light To Speed Up Chemical Reactions A catalyst is a substance that accelerates a chemical reaction without being permanently changed in the process, Stylianou said. A photocatalyst works in a similar way but is activated by light.
After absorbing light, the material reaches a higher energy state and can use that energy to drive chemical reactions more rapidly. The findings, published in the Journal of the American Chemical Society, could provide researchers with another tool for reducing greenhouse gas emissions and addressing climate change, Stylianou said. His research centers on metal organic frameworks, or MOFs, which are crystalline, porous materials with structures that can be carefully customized.
MOFs are built from positively charged metal ions surrounded by organic "linker" molecules. Their tiny pores and adjustable structures allow scientists to fine tune their properties for different applications. Millions of different MOF structures are theoretically possible, Stylianou said.
Chemistry researchers have already synthesized nearly 100,000 of them, while the properties of roughly another half-million have been predicted. An Unusual Sulfur Bond Drives the Reaction For this study, the researchers focused on a MOF called BVR-19. The material contains an unusual sulfide-to-sulfide bond that temporarily breaks when exposed to light, producing highly reactive sulfur species.
"The organic component does the important work," Stylianou said. "Instead of relying primarily on the metal atoms, our material uses its sulfur-containing organic building blocks to capture light energy and move electrons where they are needed to produce hydrogen. This represents a different way of thinking about how these materials should be designed." That approach means BVR-19 does not require an additional expensive metal catalyst, Stylianou added.
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