Electron microscopy of carbon-supported metal catalysts: From atomic-scale structural characterization to o perando mechanistic insights

Abstract Carbon-supported metal catalysts, ranging from isolated single atoms and sub-nanometer clusters to nanoparticles, are widely used in heterogeneous catalysis because of the high surface area, conductivity, tunability and defect-rich nature of carbon supports. Their catalytically relevant structures are often local, heterogeneous and dynamically evolving, making ensemble-averaged characterization insufficient for establishing reliable structure–activity relationships. Electron microscopy has therefore become essential for directly visualizing metal dispersion, coordination environments and metal–carbon interfaces across multiple length scales. Aberration-corrected STEM, combined with EELS/EDS and complementary spectroscopies, enables the identification of atomically dispersed sites, clusters and confined nanoparticles, whereas in situ and operando microscopy reveals catalyst formation, restructuring and deactivation under working conditions. Future advances will rely on realistic operando cells, statistically robust analysis and AI-assisted workflows, transforming electron microscopy from a descriptive imaging tool into a quantitative platform for understanding and designing carbon-supported metal catalysts.