This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Researchers at Oregon State University have developed a new family of materials that use light to produce hydrogen from water, opening the door to new ways of converting the sun's rays into clean energy. A collaboration led by Kyriakos Stylianou of the OSU College of Science created a photocatalyst that enables the rapid, efficient production of hydrogen.
Hydrogen is used in fuel cells for cars, in the manufacture of many chemicals, including ammonia, in metal refining and in making plastics. A catalyst is a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change, Stylianou said. Photocatalysts absorb light to reach a higher energy level and can use that energy to speed up reactions.
The findings, published in the Journal of the American Chemical Society, introduce a potential new tool to use against greenhouse gas emissions and climate change, said Stylianou, whose research focuses on crystalline, porous materials known as metal-organic frameworks, or MOFs. Made up of positively charged metal ions surrounded by organic "linker" molecules, MOFs have nanosized pores and tunable structural properties. They can be designed with a variety of components that determine a MOF's properties, and there are millions of possible MOFs, Stylianou said.
Almost 100,000 have been synthesized by chemistry researchers, and the properties of another half-million have been predicted. In this study, researchers worked with a MOF, BVR-19, that has a distinctive structural feature: a sulfide-to-sulfide bond that undergoes transient cleavage upon exposure to light, resulting in 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." No additional expensive metal catalyst is required, he added, potentially simplifying the design of future light-driven hydrogen-production systems. BVR-19 also forms spontaneously in aqueous solutions at room temperature, giving it a strong energy advantage.
Producing hydrogen by splitting water through a catalytic process is cleaner than the conventional method of deriving hydrogen from natural gas through a carbon-dioxide-producing process known as methane-steam reforming, Stylianou said. Current catalytic processes for producing hydrogen from water involve electrocatalysis—running electricity through the catalyst. The sustainability of electrocatalysis depends on using renewable energy, and to be competitive in the market, that energy has to be inexpensive.
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