Sustainable and surfactant-free high-throughput synthesis of highly dispersible zirconia nanocrystals

Herein, a cost-effective and tailored synthesis route for the preparation of cubic ZrO2 nanocrystals with high dispersibility (up to 45% by weight in H2O) is reported. The procedure is straightforward and produces uniform 2–3 nm particles of a high yield of up to 98% when applying microwave dielectric heating as a “green” method. Furthermore, it can be applied to a wide range of batch sizes (from 0.5 to 20 g ZrO2), which makes it interesting for industrial applications, and also lends itself to the preparation of yttria-stabilized ZrO2 nanocrystals with varying doping levels. Overall, the paper aims at unravelling all relevant reaction steps by means of nuclear magnetic resonance and gas chromatography-mass spectrometry. Two innovative synthesis routes are presented, which have not been considered in previous studies. Both the microstructure and chemical composition of the nanoparticles were analyzed via electron microscopy, X-ray diffraction and dynamic light scattering as well as Raman, X-ray absorption and X-ray photoelectron spectroscopy. Besides, it is demonstrated that alcoholic ZrO2 dispersions are highly suited for the preparation of nanoscale materials with different morphologies, including fibers as well as ordered mesoporous and macroporous thin films and powders. Collectively, this work provides a blueprint for the fabrication of high-quality nanoparticles and structured materials thereof and is likely to trigger further research in the field of solution-processed metal oxides.