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Graphene applied to solar hydrogen production

Hydrogen is destined to be one of the key vectors in a future circular energy system independent of fossil fuels and based on solar energy. Today, most of the hydrogen is obtained from natural gas, which is not sustainable in the long term. The largest reserve of hydrogen that we have in nature is water, which, however, requires a great energy input to “free” this hydrogen in the elemental form, H2, which is the useful one from an energy point of view. It would be most interesting in this regard to directly use sunlight to obtain hydrogen from water, just as green plants and other photosynthetic organisms do to obtain organic compounds for their own nourishment from carbon dioxide and also from water. For this purpose, materials are needed that can absorb energy in the form of light and transfer it to water molecules, facilitating its conversion into oxygen and hydrogen and thus transforming light energy into chemical energy. These materials, called photocatalysts, must have, among other properties, good electronic conductivity for efficient energy transfer. In this sense, the combination of a photocatalyst with another material with high conductivity can lead to an improvement of this artificial photosynthesis, as long as the interaction between both components is ideal. Graphene is a material that has earned much attention in recent years due to its unique properties, which include, among many others, high electronic conductivity and surface characteristics that make it a good candidate to be used as a promoter of artificial photosynthesis.

In collaboration with the University of Cantabria, researchers from the Photoactivated Processes Unit of IMDEA Energy have recently published a study on graphene as a promoter of the reactions involved in obtaining hydrogen from water in combination with perovskite-type photocatalysts.* Through different physico-chemical techniques, this work sheds light on the necessary interactions between both materials so that their combination leads to a greater process efficiency with respect to the use of the perovskites catalysts alone.

(*) Assessing the feasibility of reduced graphene oxide as an electronic promoter for photocatalytic hydrogen production over Nb-Ta perovskite photocatalysts. Catalysis Today (2020), in press, https://doi.org/10.1016/j.cattod.2020.05.027

More information: Fernando Fresno, Senior Assistant Researcher, Photoactivated Processes Unit. fernando.fresno@imdea.org

Event Date: 
Monday, July 6, 2020