Alloyed single-atom catalysts for electro- and photo- catalytic water splitting

Water splitting by using renewable energy to produce hydrogen and oxygen, can be regarded as one of the most promising approaches for sustainable energy conversion. Developing cost-effective and high-performance water splitting catalysts plays an increasingly important role in enhancing the overall efficiency. Alloyed single-atom catalysts (alloyed SACs, also known as single atom alloy), with one of the metal atoms atomically dispersed in a host metal, combine the advantages of both single atom catalysts and traditional metal alloys. They show the maximum utilization of active metal atoms and uniquely geometric as well as electronic structures, offering great potential in reducing the cost of catalyst and boosting the performance in catalytic water splitting. This review aims to provide a comprehensive summary of the development of alloyed SACs for oxygen and hydrogen evolution reactions by water splitting. We start with a brief introduction of the mechanism for water splitting under electrocatalytic and photocatalytic conditions, followed by emphasizing the merits of the formation of alloyed SACs for water splitting. Then, the case studies of electro- and photo- catalytic hydrogen and oxygen evolution via water splitting are illustrated and discussed. Finally, challenges and prospects are provided, with further continued efforts expected for achieving future exciting progress in tailoring the active sites for designing high-performance catalysts.