Self-assembly process of China rose-like β-Co(OH)₂ and its topotactic conversion route to Co₃O₄ with optimizable catalytic performance

China rose-like structured β-Co(OH)₂ was fabricated by a facile and surfactant free solvothermal method. The self-assembly process of the 3D flower-like structure was preliminarily explored via time-dependent observation. The chemical transformation achieved by thermal treatment from brucite-like β-Co(OH)₂ to spinel Co₃O₄ was investigated in detail, while the original flower-like framework of the precursor was preserved during the entire process. With increase in the temperature of heat treatment, the specific surface area decreased correspondingly. Meanwhile, propagation of cracks and the following cavitation progress were realized on petal-like flakelets. Topotactic nucleation and crystallization in the [111] direction of spinel-structured Co₃O₄ inheriting the [0001] direction of hexagonal structured β-Co(OH)₂ were analyzed in detail. The catalytic performance of the obtained Co₃O₄ materials on the thermal decomposition of ammonium perchlorate (AP) was analyzed. It was fortunately found that samples annealed at 280°C could lower the thermal decomposition temperature of AP from 450°C to 245°C, when the obtained Co₃O₄ made up 4% w/w of the mixture. This excellent performance is of great practical significance in the development of solid rocket fuels.