Antimicrobial Activity of Morphology-Controlled Cu₂O Nanoparticles: Oxidation Stability under Humid and Thermal Conditions

Metal oxides can be used as antimicrobial agents, especially since they can be fabricated into various forms such as films, masks, and filters. In particular, the durability of antimicrobial agents and the duration of their antimicrobial activity are important factors that determine their suitability for a specific purpose. These factors are related to the morphology and size of particles. The metal oxide Cu2O is often oxidized to CuO in various conditions, which reduces its antimicrobial activity. This study focused on the oxidation of nanoparticles of Cu2O with three morphologies, namely, spherical, octahedral, and cubic morphologies, in excessively humid and excessive-thermal environments for a specific duration and the antimicrobial activity of the NPs. Cu2O nanoparticles were prepared using the chemical reduction method, and their morphology could be varied by adjusting the molar ratio of OH- to Cu2+ and changing the reducing agent. It was found that cubic Cu2O was the most stable against oxidation and had the smallest reduction in antimicrobial activity. This study examined the antimicrobial activity and the oxidation stability of Cu2O NPs with different morphologies but similar particle sizes.