Green hydrogen is one of the fuels of the future because, when burned, it produces only water vapor — a harmless substance — unlike the carbon dioxide emitted by today's engines, which run on fossil fuels. Hydrogen production, however, relies on the very fuels it aims to replace. Thus, the Organic Chemistry and Catalysis research group at the University of Córdoba is working to make both the use and production of hydrogen green through a "recipe" that combines various "ingredients" and methods.
The foundation of this recipe for producing truly green hydrogen is photocatalysis, a process that converts sunlight into chemical energy using titanium dioxide, a compound commonly employed in these processes. This compound, known as a photocatalyst, is highly stable and inexpensive, but it cannot absorb a large amount of sunlight. In fact, it loses more than 90% of the light it receives almost instantly, even before it can convert it into hydrogen. Hence, the research team has added other elements and treatments to the "recipe" that increase and improve hydrogen generation.
In laboratory tests simulating sunlight, the team added various metals to titanium dioxide and found that gold or platinum (from the group of noble metals) are the most efficient at converting captured sunlight into chemical energy and producing hydrogen. A more affordable alternative to costly gold or platinum would be copper, a non-noble metal whose results come close to those of noble metals. Therefore, "copper would be a very promising catalyst for scaling up hydrogen production to an industrial level," says Juan Martín Gómez, a researcher at the University of Córdoba.
In the study, the type of metal used in the photocatalytic process proved to be just as important as the way the metal is incorporated into the catalyst. For the metals to deposit properly onto titanium dioxide, the study showed that a method called "deposition–precipitation," which disperses the metal into small particles and, thus, promotes higher hydrogen production, was more effective. It was also essential to subject the metals to a thermal pretreatment to remove certain compounds that were "poisoning" the metal-titanium interaction. The study concluded that to maximize hydrogen production using solar energy, simply depositing a metal on titanium dioxide is not enough. Rather, it is essential to achieve a high degree of metal dispersion and to ensure the metal is clean by removing other contaminants.
The study, funded by the "(Photo)(electro)catalytic valorization of glycerol into energy and value-added products" project (PID2022-142275OB-I00, MCIU/AEI/10.13039/501100011033/ERDF, EU) and published in the International Journal of Hydrogen Energy, has made strides toward improved photocatalyst design to ensure that green hydrogen production is truly green, cost-effective, scalable, and more efficient.
Reference:
Juan Martín-Gómez, Julia Morales-Roldán, Jesús Hidalgo-Carrillo, Alberto Marinas, Francisco J. Urbano, "Structure–activity relationships in metal/TiO₂ photocatalysts for hydrogen production via glycerol photoreforming," International Journal of Hydrogen Energy, Volume 263, 2026, 156821, ISSN 0360-3199, https://doi.org/10.1016/j.ijhydene.2026.156821 .
International Journal of Hydrogen Energy
10.1016/j.ijhydene.2026.156821.
Structure–activity relationships in metal/TiO2 photocatalysts for hydrogen production via glycerol photoreforming
31-Jul-2026