Non-noble metal single-atom catalysts prepared by wet chemical method and their applications in electrochemical water splitting

Water splitting by electrolysis is an appealing pathway for sustainable hydrogen production. The practical performance of water splitting is highly dependent on the efficiency of electrocatalysts, which can promote the anodic oxygen evolution reaction (OER) or cathodic hydrogen evolution reaction (HER). Downsizing the metal nanostructures to atomic level to construct single-atom catalysts (SACs) has attracted enormous attention due to its distinct advantages in maximizing the efficiency of metal atom utilization and enhancing activity over corresponding metal nanoparticles. Research on SACs towards electrochemical water splitting application is an emerging field and intensive investigations have been focused on their rational syntheses and applications in HER/OER. In this review, we focus on the wet chemical method developed to prepare non-noble metal based SACs with an emphasis on the synthetic strategies and structure-activity relationship between single metal atoms and catalytic activity. Finally, the challenges and future opportunities for application of single-atom catalysts in water splitting are briefly addressed.