Facile synthesis of zirconia nanoparticles using a salt-assisted ultrasonic spray pyrolysis combined with a citrate precursor method

Abstract Current synthesis processes for zirconia nanoparticles require expensive precursors or templates, complex steps and long reaction times, and produce highly agglomerated nanoparticles. In this study, we demonstrated a simple and continuous approach for synthesizing zirconia nanoparticles by combining a salt-assisted ultrasonic spray pyrolysis with a citrate precursor method. This process allows tuning of the morphology and size, where hollow sub-micron particles are transformed to minute nanoparticles by controlling (through a chelating reaction) the diffusion rate of zirconium cations in a pyrolysis step. The synthesized nanoparticles (average diameter: ∼10 nm) are characterized by a highly crystalline tetragonal structure, uniform particle-size distribution, and high specific surface area. A detailed mechanism for generating tiny nanoparticles, via this process, is presented and the optical properties of the nanoparticles are evaluated through an ultraviolet–visible (UV–vis) diffuse reflectance spectrum and converted Kubelka-Munk function.