Microreactor-Based TG-TEM Synchronous Analysis.

Abstract

It is challenging to measure the heating-induced mass change of the material during its morphological/structural evolution process. Herein, a silicon microreactor is developed for thermogravimetric-transmission electron microscopy synchronous analysis (TG-TEM synchronous analysis). A self-heating resonant microcantilever for mass-change detection and a dummy microcantilever with electron-beam transparent SiNx windows for in situ TEM imaging are integrated back-to-back inside the microreactor. The TEM resolution of the microreactor reaches the Ångström level in an air atmosphere of 100 mbar, and the TGA function is realized by the heatable resonant microcantilever. The TG-TEM synchronous analysis has been successfully used to characterize two Ni(OH)2 samples. During the in situ TEM observing process, the desorption of the intercalated H2O molecules and dehydration of the lattice OH groups in the amorphous Ni(OH)2·xH2O nanosheets can be clearly distinguished from the microcantilever-based TGA. For single-crystal Ni(OH)2 nanosheets, the TG-TEM synchronous analysis can distinguish the desorption of physiosorbed water, the condensation of surface OH groups, and the dehydration of lattice OH groups. The amorphous Ni(OH)2 nanosheets transformed to polycrystalline NiO completed at 290 °C, and the decomposition from the single-crystalline Ni(OH)2 nanoplates to NiO at 315 °C is also clearly recognized. The proposed microreactor-based TG-TEM synchronous analysis provides an interrelated characterization platform to obtain more comprehensive information on materials.