Wendong Liu, Michael Kappl,* and Hans-Jürgen Butt

ACS Nano 2019, 13 (12), 13949-13956.

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    Supraparticles consisting of nano- or microparticles have potential applications as e.g., photonic crystals, drug carriers, or heterogeneous catalysts. To avoid the use of solvent or processing liquid one can make supraparticles by evaporating droplets of aqueous suspensions from super-liquid-repellent surfaces. Herein, a method to adjust the porosity of supraparticles is described; a high porosity is desired, e.g., in catalysis. To prepare highly porous TiO2 supraparticles, polymer nanoparticles are co-dispersed in the suspension. Supraparticles are formed through evaporation of aqueous suspension droplets on superamphiphobic surfaces followed by calcination of the sacrificial polymer particles. The increase of porosity of up to 92%, resulted in enhanced photocatalytic activity while maintaining sufficient mechanical stability.