(186k) Impacts of a Low-Temperature Calcination on the Characteristics of Monodisperse, Surface-Clean, Supported Nanoparticle Catalysts

Traditional methods of preparing supported nanoparticle catalysts require the use of stabilizing ligands that passivate the nanoparticle surface to reduce undesired morphology changes. While effective in maintaining monodispersity during synthesis, stabilizing ligands often significantly hinder catalytic activity as they compete with reagents for active sites and are therefore typically removed through a high-temperature annealing step prior to use. It is well documented that exposure to high temperatures results in significant nanoparticle growth ultimately resulting in polydisperse populations and reduced surface area for catalysis; however, the detrimental effects of thermal treatments on catalyst surfaces beyond those associated with size changes are typically overlooked. In this work, we demonstrate that even a low-temperature calcination has detrimental effects on catalyst properties including changes in nanoparticle morphology that result in a significant decrease in activity, a change in surface hydrophilicity, a change in activation energy, and results in the formation of an induction time when utilized in a reaction. While calcination remains a widely used method catalyst activation, the negative effects of high temperatures on catalyst properties are often overlooked.