On-chip gas reaction nanolab for in situ TEM observation.

Abstract

The catalysis reaction mechanism at nano/atomic scale attracted intense attention in the past decades. However, most in situ characterization technologies can only reflect the average information of catalysts, which leads to the inability to characterize the dynamic changes of single nanostructures or active sites under operando conditions, and many micro-nanoscale reaction mechanisms are still unknown. The combination of in situ transmission electron microscopy (TEM) holder system with MEMS chips provides a solution for it, where the design and fabrication of MEMS chips are the key factors. Here, with the aid of finite element simulation, an ultra-stable heating chip was developed, which has an ultra-low thermal drift during temperature heating. Under ambient conditions within TEM, atomic resolution imaging was achieved during the heating process or at high temperature up to 1300 °C. Combined with the developed polymer membrane seal technique and nanofluidic control system, it can realize an adjustable pressure from 0.1 bar to 4 bar gas environment around the sample. By using the developed ultra-low drift gas reaction cells, the nanoparticle's structure evolution at atomic scale was identified during reaction.