The Systematic Correlation Between Synthesis Parameters and the Particle Size of Nickel Oxide Nanocatalysts Prepared by the Sol–Gel Method

In this work, the sol-gel synthesis of nickel oxide (NiO) nanoparticles was systematically examined with respect to key parameters, including precursor type, reagent molar ratio, reaction time, and calcination temperature. A comparative evaluation of different nickel-based salts identified nickel nitrate as the most suitable precursor. Structural–phase characterization by X-ray diffraction (XRD) demonstrated that the nanoparticles synthesized at varying reagent ratios possessed well-defined crystalline phases, with an average crystallite size of ~11 nm. Prolonged reaction times were observed to promote agglomeration processes. Raman spectroscopic analysis revealed the presence of phonon and magnon vibrational modes, which were strongly dependent on particle size and calcination conditions. Transmission electron microscopy (TEM) confirmed a particle size distribution in the range of 3÷19 nm. Collectively, these results establish the synthesis–structure relationship and provide a framework for defining optimal conditions for preparing NiO nanocatalysts.

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