Fast Gas-Solid Reaction Kinetics of Nanoparticles Unveiled by Millisecond In Situ Electron Diffraction at Ambient Pressure.

Abstract

Acquiring the kinetics of gas-nanoparticle fast reactions under ambient pressure is a challenge owing to the lack of appropriate in situ techniques. Now an approach has been developed that integrates time-resolved in situ electron diffraction and an atmospheric gas cell system in transmission electron microscopy, allowing quantitative structural information to be obtained under ambient pressure with millisecond time resolution. The ultrafast oxidation kinetics of Ni nanoparticles in oxygen was vividly obtained. In contrast to the well-accepted Wagner and Mott-Cabrera models (diffusion-dominated), the oxidation of Ni nanoparticles is linear at the initial stage (<0.5 s), and follows the Avrami-Erofeev model (n=1.12) at the following stage, which indicates the oxidation of Ni nanoparticles is a nucleation and growth dominated process. This study gives new insights into Ni oxidation and paves the way to study the fast reaction kinetics of nanoparticles using ultrafast in situ techniques.