Layered double hydroxides supported noble-metal single-atom catalysts: precise synthesis, microenvironment regulation, and diverse applications

Noble-metal single-atom catalysts (SACs) have arisen as a research hotspot in heterogeneous catalysis resulting from superior noble-metal-atom utilization, well-defined catalytic centers, and tunable microenvironments. Recently, the advent and rise of noble-metal SACs supported by layered double hydroxides (LDHs) have injected fresh vitality and vigor into this research field. LDHs offer distinct advantages as the support of SACs, such as an ordered and adjustable crystal structure, a two-dimensional layered structure possessing a large specific surface area, facile synthesis with cost-effectiveness, and strong co-catalytic metal-support interaction between LDHs and noble-metal single atoms. In this review, we classified and comprehensively outlined the current synthesis strategies of noble-metal SACs supported by LDHs, and conducted an in-depth analysis of the specific mechanisms underlying each strategy. Subsequently, considering the critical role of the microenvironment of SACs in affecting their catalytic-related properties, we discussed the current microenvironment regulation strategies of LDH-supported noble-metal SACs. We also provide an introduction to the characterization techniques for noble-metal singe-atom sites in LDH-supported noble-metal SACs. Furthermore, we outlined the diverse applications of LDH-supported noble-metal SACs in various catalytic fields and discussed the roles played by noble-metal atoms and LDHs in relevant catalytic processes. Finally, we delineated the challenges and future research directions for the development of LDH-supported noble-metal SACs.