Highly Efficient and Controlled Fabrication of Supraparticles by Leidenfrost Phenomenon

Supraparticles (SPs) are agglomerates of smaller particles, which show promising applications in catalysis, sensing, and so forth. Preparation of SPs with controlled sizes, components, and structures in an efficient, scalable, and environmentally friendly way has become an urgent demand for the development of SPs. Herein, a method to fabricate SPs based on the Leidenfrost phenomenon is described. By dropping a nano-/microparticle dispersion on a metal plate at the Leidenfrost temperature (T_LF) or higher, the solvent evaporates quickly, and SPs can be formed within 1 min. To understand the influence of various factors on the properties of SPs, and also to optimize the fabrication of SPs, the effects of metal surface roughness and primary particle concentration on T_LF were carefully observed. Plates with a higher roughness as well as a higher primary particle concentration could trigger a lower T_LF. Combining the regulation of composition and volume of the droplets, SPs with different sizes, compositions, and structures were precisely fabricated. Furthermore, highly porous titanium dioxide (TiO₂) SPs with enhanced photocatalytic performance were fabricated via this method, showing the merits of the method in practical applications. This simple, efficient, and green method provides a new approach for controlled and large-scale fabrication of SPs with various functions.