Advancements in Single-Atom Catalysts: Synthesis, Characterization, and Applications in Sensing Technologies.

Single-atom catalysts (SACs) have rapidly progressed from early proof-of-concept studies to high-performance sensing platforms. Their atomically dispersed active sites and tunable coordination environments, offer superior catalytic activity and selectivity compared with conventional nanocatalysts. Recent advances in support engineering, spanning carbon nanomaterials, metal oxides, and metal organic frameworks have enabled precise control over SAC composition, electronic structure, and stability under complex operating conditions. This review summarizes the current state of SAC research from three complementary perspectives. First, it compare top-down and bottom-up synthesis strategies, emphasizing scalable approaches that preserve single-atom dispersion. Second, it outlines the characterization techniques, highlighting how advanced spectroscopy, microscopy, and theoretical calculations are integrated to correlate coordination environments with catalytic performance. Third, it discusses emerging sensing applications including biosensing, environmental monitoring, gas and electrochemiluminescence detection, and photoelectrochemical analysis where SAC-based materials achieve record-low detection limits. Despite significant advancements, key challenges remain: (i) preventing atom aggregation under harsh electrochemical conditions, (ii) integrating SACs into miniaturized devices, and (iii) establishing standardized metrics that bridge theoretical predictions and practical performance. This review concludes that addressing these issues will advance SACs toward real-time sensing, with multi-atom cooperative sites and AI-assisted catalyst design as promising strategies to unlock their full potential in next-generation analytical platforms.