Single-Atom Catalysts: A Key Strategy for Sustainable Fuel Production?

by Chema Arcos

The incorporation of single-atom catalysts (SACs) in electrodes is emerging as a promising approach for producing green fuels, such as hydrogen, from solar energy. A recent study co-authored by Prof. Jordi Arbiol explores the key factors and challenges in optimizing this technology.

Hematite is a material with great potential in technologies for producing fuels and chemical products of interest. For example, it is used in photoelectrochemical electrodes (PECs), which use solar energy to split water molecules to generate hydrogen. However, the low performance of these electrodes has been an obstacle to their large-scale application. In this context, a recent study involving ICREA Prof. Jordi Arbiol (head of the ICN2 Advanced Electron Nanoscopy Group) has evaluated how the incorporation of single-atom catalysts (SACs) can improve the efficiency of this technology. The study, published in the journal The Innovation (Cell Press), is presented as a commentary and it is co-authored by Prof. Peng-Yi Tang, former PhD and postdoc at ICN2 and now Professor at the Shanghai Institute of Microsystem and Information Technology.

SACs, like any other catalyst, are substances capable of accelerating the rate of a chemical reaction. However, what makes them different is that they have active atoms that are isolated and distributed over their surface or matrix. This makes them highly selective and efficient catalysts. They currently have many applications, including in the chemical and pharmaceutical industries. However, their use in photoelectrochemical electrodes has not been widely investigated and established.

The researchers analysed the scientific evidence currently available in this field. They evaluated how the incorporation of SACs, with atoms such as iridium and ruthenium, is useful in optimising the separation of water molecules, facilitating the transport of electrical charges and accelerating the oxidation reaction that takes place at the electrode. Using advanced techniques such as transient spectroscopy, atomic resolution related electron microscopies and spectroscopies, and theoretical calculations, it has been possible to show how these independent atoms facilitate charge transport and reduce energy loss in the process, making it more efficient.