Recent advances in heterogeneous single-atom nanomaterials: From engineered metal-support interaction to applications in sensors

The heterogeneous single-atom nanomaterials (HSANs) are being increasingly embodied in the field of sensors due to their excellent performance on improving sensitivity based on the active centers formed by the metal-support interaction and the high metal utilization efficiency. In this review, we comprehensively summarize the metal-support interactions during the process of HSANs construction, including the interactions between metal single-atom and laminar carbon-based nanomaterials, MOFs/MOFs-derived nanomaterials, metal oxidation/sulfide nanomaterials, and metal nanomaterials. These metal-support interactions contribute to the functional characteristics of HSANs due to the adjustable active centers such as M-Nx, M-Ox, and M-Sx, which lay good foundation for sensor applications. Then, the sensors based on electrocatalysis, photocatalysis, catalytic colorimetry, photoelectrochemistry and the synergetic sensing of active centers in HSANs are summarized. The well-defined active centers constructed by the metal-support interaction are also highlighted to elucidate the functional mechanism and structure-activity relationship in sensors. Finally, challenges and opportunities on further applications of HSANs in sensors are put forward.