Quantitative Measurements of Catalytic Activity of Single-Atom and Nanoparticle Palladium Catalysts for Sensitive Detection of Methane Using Cantilever-Based Temperature-Programmed Reduction Technique

In this work, the catalytic activity of isolated single atoms (SAs) was quantitatively measured using an integrated resonant microcantilever, which can measure sub-picogram-level mass-changes of Pd-SAs during the reduction process under an H 2 -containing atmosphere (i.e., cantilever-based H 2 -TPR technique). The ultra-sensitive cantilever-TPR measurements indicate that Pd-SAs exhibit higher catalytic activity than Pd nanoparticles with an average diameter of 3nm. The higher catalytic activity of Pd-SAs can be verified through gas sensing experiments because Pd-SAs show satisfactory responses to ppm-level methane. In contrast, the response of Pd-NPs to 100 ppm methane is negligible.