Electron paramagnetic resonance spectroscopy for the analysis of single-atom catalysts

Single-atom catalysts (SACs) are an important material class, lying at the forefront of precision design for heterogeneous catalysis research. Despite extensive investigations of their structure and reactivity using state-of-the-art analytical tools, new approaches are sought to improve the understanding of their properties and catalytic behavior. This review highlights the often-overlooked potential of electron paramagnetic resonance (EPR) spectroscopy, which is exceptionally suited to studying isolated paramagnetic species. EPR provides valuable complementary insights into SACs, including metal oxidation state, dispersion degree, local coordination environment, and catalytically relevant features of support materials. To enhance the technique’s accessibility, we provide a tutorial on EPR, summarize significant findings to date, place them within a broader methodological framework for SAC applications, and identify key directions for future research.