Researchers at UC Santa Cruz South and the China University of Technology have developed a graphene-based nanostructured composite material that shows impressive performance as a catalyst for the electrochemical splitting of water to produce hydrogen. An efficient, low-cost catalyst is essential for realizing the promise of hydrogen as a clean, environmentally friendly fuel.
The team has been investigating the use of carbon-based nanostructured materials as catalysts for the reaction that generates hydrogen from water. In a recent study, they obtained good results by incorporating ruthenium ions into a sheet-like nanostructure composed of carbon nitride. Performance was further improved by combining the ruthenium-doped carbon nitride with graphene, to form a layered composite.
"The bonding chemistry of ruthenium with nitrogen in these nanostructured materials plays a key role in the high catalytic performance," Chen said. "We also showed that the stability of the catalyst is very good."
In the new composite material, the ruthenium ions embedded in the carbon nitride nanosheets change the distribution of electrons in the matrix, creating more active sites for the binding of protons to generate hydrogen. Adding graphene to the structure further enhances the redistribution of electrons. "The graphene forms a sandwich structure with the carbon nitride nanosheets and results in further redistribution of electrons. This gives us greater proton reduction efficiencies," the team said.
The electrocatalytic performance of the composite was comparable to that of commercial platinum catalysts, the authors reported. They added, however, that researchers still have a long way to go to achieve cheap and efficient hydrogen production.