Advancements and insights into single-atom catalysts for environmental and energy applications

Future renewable energy supplies and sustainable ecosystems depend on many important catalytic processes. The search for stable and efficient catalysts is important for the promotion of these catalytic processes. Single-atom catalysts (SACs), which integrate the benefits of both homogeneous and heterogeneous catalysis, are increasingly attracting the attention of researchers. The individual metal atoms can be stabilized on the carrier by various unsaturated chemical sites or spatial confinement to maximize the efficiency of atom utilization. However, their high surface energy necessitates careful limitation of single-atom loading to prevent aggregation, which can adversely affect catalytic performance, even though individual atoms exhibit high activity. Therefore, there is an urgent need to explore the coordination structure of SACs as well as the catalytic mechanism to achieve the regulation and optimization of single-atom catalysts and to stimulate their potential application in sustainable development. In this paper, we review several important preparation approaches of single-atom catalysts and the research progress in the fields of contaminant purification and energy conversion in recent years. We also discuss the catalytic mechanisms and structure-activity relationships, specifically addressing the influence of surface species and supports on catalytic activity, as well as the effects of the unique structural and electronic properties of single-atom centers, modulated by metal/support interactions, on catalytic activity and selectivity. This review draws on data derived from a systematic sorting and analysis of relevant publications in the Web of Science and Scopus databases. Through an in-depth examination of these literatures, this paper aims to elucidate the key trends in the development of SACs in the fields of energy and environment, while highlighting their unique scientific value and significant application potential for readers. DFT calculations have revealed how the unique structure and electronic properties of single-atom centers affect catalytic activity and selectivity through metal/carrier interactions, providing a new theoretical basis for the design and application of SACs. Finally, the future of single-atom catalysis is envisioned, aiming to provide insights for future studies of SACs in sustainable environmental development and renewable energy supply.