Highly Efficient and Controlled Fabrication of Supraparticles by Leidenfrost Phenomenon

Abstract

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 (TiO 2 ) 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.

Structure Formation in Supraparticles Composed of Spherical and Elongated Particles

“…30,31 Further, the fast evaporation conditions make it quite difficult to control the final supraparticle shape and the distribution of the colloidal particles inside the supraparticle. 32 For levitated droplets, additional parameters such as the thermal conductivity of the substrate can introduce challenges in controlling the resulting supraparticle shapes. 30,32 Alternatively, supraparticles can be fabricated by evaporating droplets supported on solid substrates.…”

“…These methods are typically performed at high temperatures, where evaporation takes only a few seconds. Therefore, studying structure formation with these techniques in real time is difficult and requires complex instruments, such as rotating anode-based X-ray sources or small-angle X-ray scattering. , Further, the fast evaporation conditions make it quite difficult to control the final supraparticle shape and the distribution of the colloidal particles inside the supraparticle . For levitated droplets, additional parameters such as the thermal conductivity of the substrate can introduce challenges in controlling the resulting supraparticle shapes. , …”

“…32 For levitated droplets, additional parameters such as the thermal conductivity of the substrate can introduce challenges in controlling the resulting supraparticle shapes. 30,32 Alternatively, supraparticles can be fabricated by evaporating droplets supported on solid substrates. The wetting property of the substrate is important, as it directly determines the deposition characteristics in the contact region.…”

Self-Propelled Polymeric Droplet in Leidenfrost State on a Superheated Ratchet Surface

“…As a result, the maximum reaction rate for the liquid-phase chemical reaction is obtained when the Leidenfrost droplet is used as the chemical reactor. Therefore, in recent years, attempts to apply Leidenfrost droplets to chemical processes have increased, for example, organic synthesis, particle fabrication, , and drying of suspension . However, from a practical perspective, the minuscule throughput of a single Leidenfrost droplet poses an issue that should be addressed.…”