This study investigates the sonochemical deposition of ZnO nanoparticles onto a monolithic cordierite honeycomb substrate. The research systematically evaluated the impact of two key parameters, sonication power (100–400 W) and zinc acetate dihydrate concentration (10–40 mM). The successful formation of the ZnO phase on the cordierite support was confirmed through X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. The crystallite size of the deposited ZnO nanoparticles was determined using both the Scherrer equation and Rietveld refinement methods applied to XRD data. The findings revealed that an increase in sonication power from 100 to 400 W, at a fixed zinc acetate concentration of 40 mM, resulted in a significant reduction of ZnO crystallite size. Furthermore, this higher power enhanced the uniformity of the nanoparticle coating on the honeycomb channels. A similar trend was observed with precursor concentration; increasing the zinc acetate concentration from 10 to 40 mM led to a further decrease in nanoparticle crystallite size. Based on these results, the study identifies the optimized synthesis conditions for achieving the most favorable nanoparticle characteristics. The sample prepared with a sonication power of 400 W and a zinc acetate concentration of 20 mM was determined to provide the optimal outcome.
