Dimensionally Tunable Rod-Shaped Zirconia Particles via Bottom-Up Assembly

The synthesis of anisotropic particles is highly desirable due to their broad potential applications. However, achieving well-controlled anisotropic morphologies without templates remains a significant challenge. In this work, we present a solvothermal approach utilizing cosolvent systems to synthesize uniform, monodispersed rod-like zirconia particles with precisely controlled dimensions. Comparative studies between single-solvent systems (water and ethanol) and water/alcohol cosolvent systems (water/methanol, water/ethanol, and water/isopropanol) reveal that the use of cosolvents significantly promotes the formation of anisotropic (rod-like) zirconia particles. Furthermore, the dimensions of these rod-like particles can be finely tuned by adjusting the cosolvent (water/ethanol) volume ratio. The formation of rod-like structures without template is attributed to a bottom-up assembly process, comediated by cosolvent systems and key solvothermal kinetic parameters, including synthesis temperature, reaction time, and precursor pH. Building on this strategy, rod-like monoclinic zirconia particles synthesized from ZrOCl₂·8H₂O in water/ethanol cosolvent systems exhibits tunable lengths ranging from 82 ± 0.6 to 929 ± 13.8 nm and aspect ratios from 1.3 to 3.8. Additionally, the developed method enables scalable synthesis with a high production yield of 98.8%, producing well-crystallized rod-like monoclinic zirconia particles with an aspect ratio of approximately 2.5.