Real-time observation of phase transition from layered to spinel phase under electron beam irradiation

Abstract

Transition metal hydroxides (TM(OH)2) have drawn significant attention for their potential applications in the environmental and energy field. In this study, we investigated the phase transition of cobalt hydroxide (Co(OH)2) under electron beam irradiation using in situ high-resolution transmission electron microscopy. Both the α- and β-Co(OH)2 phases underwent a phase transition to a spinel Co3O4 phase, forming nanograins with a porous morphology. However, the α-Co(OH)2 showed a faster phase transition and dramatic volume shrinkage during the phase transition. Our results provide a detailed explanation of the mechanism behind the deterioration of the layered structure and the emergence of defects during the phase transition.