In situ observation of the thermally induced growth of platinum-nanoparticle catalysts using high-temperature X-ray diffraction.

Fundamental understanding about the thermal stability of nanoparticles and deliberate control of structural and morphological changes under reactive conditions is of general importance for a wide range of reaction processes in heterogeneous and electrochemical catalysis. Herein, we present a parametric study of the thermal stability of carbon-supported Pt nanoparticles at 80 °C and 160 °C, with an initial particle size below 3 nm, using in situ high-temperature X-ray diffraction (HT-XRD). The effects on the thermal stability of carbon-supported Pt nanoparticles are investigated with control parameters such as Brunauer-Emmet-Teller (BET) surface area, metal loading, temperature, and gas environment. We demonstrate that the growth rate exhibits a complex, nonlinear behavior and is largely controlled by the temperature, the initial particle size, and the interparticle distance. In addition, an ex situ transmission electron microscopy study was performed to verify our results obtained from the in situ HT-XRD study.