Oregon State University researchers have developed a new family of advanced materials that convert water into energy-producing hydrogen using only sunlight, offering a potential clean-energy alternative to solar panels and concentrated solar energy solutions.
The OSU College of Science team said their new approach, which enables high-speed, high-efficiency hydrogen production, could provide a solar-powered source of hydrogen for automotive fuel cells and other chemical manufacturing processes.
Electrocatalysis From Sunlight Offers Energy Without Solar Panels
In a statement announcing the new material, OSU team leader Kyriakos Stylianou explained that a catalyst is a material or substance that increases the rate of a chemical reaction while maintaining its own chemical structure. A subgroup of those materials, photocatalysts, absorb light energy, increasing their ability to speed up reactions.
Stylianou’s previous work focused on crystalline, porous materials called metal-organic frameworks (MOFs). These unique materials are made up of positively charged metal ions surrounded by what the research team termed “linker” molecules. Structurally, the OSU team said that MOFs also have nanosized ‘pores’ and other “tunable structural properties.”
“They can be designed with a variety of components that determine the MOF’s properties, and there are millions of possible MOFs,” they explained.
While scientists have already synthesized nearly 100,000 different MOFs, the team said that the chemical and structural properties of another 500,000 “have been predicted.”
Photovoltaic MOF BVR-19 Enables Highly Efficient Hydrogen Production
To explore sun-powered clean energy alternatives to solar panels, Stylianou and colleagues conducted experiments with an established MOF called BVR-19. The OSU team said they chose this MOF because it has a sulfide-to-sulfide bond that “undergoes transient cleavage upon exposure to light, resulting in reactive sulfur species.”
Stylianou said this structure means that the material’s organic component “does the important work.”
“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.”
The researcher noted that this energy-capture and conversion process results in efficient hydrogen production.
Critically, the approach requires no outside power source beyond sunlight and no added costly metallic catalysts, which Stylianou said simplifies the design of a sunlight-driven hydrogen production system based on his team’s approach.
The researchers also noted that BVR-19 is synthesized in aqueous solutions and at room temperature, “spontaneously” providing it with a ‘strong energy advantage’ over alternative photovoltaic MOFs.
“By changing the metal while keeping the rest of the material essentially the same, we discovered why some versions of the MOF work much better than others,” Styliano explained, adding that this approach “represents a different way of thinking about how these materials should be designed.”
“Clean” Process Offers Cost and Environmental Savings
When discussing the approach’s advantages over current methods for producing hydrogen from water, the team highlighted the current need for an electricity source to enable electrocatalysis. This means that the process’ sustainability depends on using renewable energy, such as sunlight.
The current approach of methane-steam reforming can produce a kilogram of hydrogen for roughly $1.50. However, producing renewable, “green” hydrogen is “about $5 a kilogram.”
Stylianou said their demonstrated approach “provides a blueprint for designing better materials that can bring down the cost of green hydrogen.” He also highlighted the environmental benefits of splitting water to harvest hydrogen compared to the current process, which captures hydrogen using natural gas “via a carbon-dioxide-producing process known as methane-steam reforming.”
“These findings provide new design rules for creating more effective materials for solar fuel production,” Stylianou concluded.
Christopher Plain has spent the last six years as Associate News Editor and Head Science Reporter at The Debrief. Follow and connect with him on X, learn about his novels at plainfiction.com, or email him at christopher@thedebrief.org.