Flash-within-flash synthesis of gram-scale solid-state materials.

Sustainable manufacturing that prioritizes energy efficiency, minimal water use, scalability and the ability to generate diverse materials is essential to advance inorganic materials production while maintaining environmental consciousness. However, current manufacturing practices are not yet equipped to fully meet these requirements. Here we describe a flash-within-flash Joule heating (FWF) technique-a non-equilibrium, ultrafast heat conduction method-to prepare ten transition metal dichalcogenides, three group XIV dichalcogenides and nine non-transition metal dichalcogenide materials, each in under 5 s while in ambient conditions. FWF achieves enormous advantages in facile gram scalability and in sustainable manufacturing criteria when compared with other synthesis methods. Also, FWF allows the production of phase-selective and single-crystalline bulk powders, a phenomenon rarely observed by any other synthesis method. Furthermore, FWF MoSe2 outperformed commercially available MoSe2 in tribology, showcasing the quality of FWF materials. The capability for atom substitution and doping further highlights the versatility of FWF as a general bulk inorganic materials synthesis protocol.

Robust Superhydrophobic Surfaces via the Sand-In Method.

Superhydrophobic surfaces have gained sustained attention because of their extensive applications in the fields of self-cleaning, anti-icing, and drag reduction systems. Water droplets must have large apparent contact angle (CA) (>150°) and small CA hysteresis (<10°) on these surfaces. However, previous research usually involves complex fabrication strategies to modify the surface wettability. It is also challenging to maintain the temporal and mechanical stability of the delicate surface textures. Here, we develop a one-step solvent-free sand-in method to fabricate robust superhydrophobic surfaces directly atop various substrates with an apparent CA up to ∼163.8° and hysteresis less than 5°. The water repellency can withstand 100 Scotch tape peeling tests and remain stable after being stored under ambient humid conditions in Houston, Texas, for 18 months or being heated at 130 °C in air for 24 h. The superhydrophobic surfaces have excellent anti-icing ability, including a ∼2.6× longer water freezing time and ∼40% smaller ice adhesion strength with the temperature as low as -35 °C. Since the surface layers are fabricated by sanding the substrates with the powder additives, the surface damage can be repaired by a direct re-sanding treatment with the same powder additives. Further sand-in condition screenings broaden surface wettability from hydrophilic to superhydrophobic. The sand-in method induces the surface modification and the formation of the tribofilm. Surface and materials characterizations reveal that both microstructures and nanoscale asperities of the tribofilms contribute to the robust superhydrophobic features of sanded surfaces.