Cooperative effect of Pt single-atoms and nanoparticles supported on carbonaceous materials: Catalytic NO decomposition as a probe reaction

Activated carbon containing highly dispersed platinum (Pt/C with ca. 1 wt.%) catalyst was synthesized according to the simple sonochemistry route followed by a drying step in air at 130 °C. STEM-HAADF micrographs indicate the presence of Pt single atoms (SAs) homogeneously dispersed on the activated carbon. The catalytic decomposition of NO has been investigated on samples pre-reduced at 250 °C and 500 °C. The Pt SAs remain stable and exhibit a surprisingly high activity which does not reflect the usually observed structure-sensitivity of NO dissociation. In addition, remarkable catalyst stability is observed after reaction at 650 °C in the presence of water. On the other hand, pre-reduction at 500 °C induces a strong deactivation related to a coalescence process with the subsequent generation of large Pt clusters, despite some small metal nanoparticles are still present in the sample. Accordingly, the structure-sensitivity of this reaction is restored. All these observations have been rationalized through the examinations of various reaction mechanisms.