Recent advances in synergistically enhanced single-atomic site catalysts for boosted oxygen reduction reaction

Abstract

The development of electrocatalysts for the oxygen reduction reaction (ORR) with high activity and cost-effectiveness is indispensable for sustainable energy storage and conversion technologies. Featured with maximum atomic efficiency and well-defined structure characteristics, carbon-based single-atomic site (SAS) catalysts are regarded as the most potential next-generation ORR catalysts. Despite the substantial efforts on the study of SAS catalysts, there still exists a large gap between them and platinum group metal (PGM) catalysts in the performance. Particularly, the unique metal-support interactions are believed to alter the charge state of the SAS by electron transfer between SAS and the support, resulting in the activated reactants and enhanced catalytic process of SAS catalysts. Inspired by this, the addition of some synergistic components is desirable to accurately tune the interactions and endow the SAS with the optional local environment, leading to improved performance. In this review, we provide a comprehensive overview of recent advances in synergistically enhanced SAS for boosted ORR. First, ORR mechanism and description of SAS catalysts towards ORR are provided. Then, a variety of novel synthetic strategies and advanced characterization techniques for SAS catalysts are briefly introduced. Emphatically, several synergistic components for SAS were systematically summarized. Finally, the current challenges and perspectives are proposed for the future development of SAS catalysts towards ORR. A comprehensive overview of recent advances in SAS catalysts for boosted ORR is provided, with a strong emphasis on the role of synergistic components for metal single sites. • The ORR mechanisms, novel synthesis strategies of single-atomic site (SAS) catalysts are introduced. • The interactions between SAS and synergistic components are emphasized. • Future trends and challenges for the development of synergistically enhanced SAS catalysts are highlighted.