Kinetics and Mechanisms of the Thermal Decomposition of Copper(II) Hydroxide: A Consecutive Process Comprising Induction Period, Surface Reaction, and Phase Boundary-Controlled Reaction

This study focused on the kinetics and mechanisms of the thermal decomposition of Cu(OH)2 as a potential processing route to produce CuO nanoparticles. The physico-geometric reaction behaviors were studied using available physicochemical techniques and microscopic observation. The kinetic modeling of the reaction process to produce CuO nanoparticles was examined via the kinetic analysis of the mass-loss data recorded under different heating conditions. The reaction exhibited specific physico-geometric kinetic characteristics, including an evident induction period, a subsequent sigmoidal mass-loss behavior under isothermal conditions, and a long-lasting reaction tail under linearly increasing temperature conditions. During the first mass-loss step characterized by the sigmoidal mass-loss behavior, the crystallite size of the produced CuO was constant, and the specific surface area increased systematically. The second mass-loss step during the reaction tail was accompanied by the crystal growth of CuO. Therefore, the end of the first mass-loss step was the most efficient reaction stage to obtain CuO nanoparticles. The overall kinetic process that reaches this reaction stage was successfully demonstrated as consecutive physico-geometric processes comprising the induction period, surface reaction, and one-dimensional phase boundary-controlled reaction, providing the kinetic parameters for each component step.