Superhydrophobic fluorescent micro-/nano-composites from carbon dots encapsulated in CaCO₃-SiO₂

In this paper, polyamine-functionalized carbon dots (CDs) were synthesized by means of low temperature (<100°C) carbonization of citric acid at the presence of polyethylenimine (PEI), resulting spherical calcium carbonate micro-particles from inverse micro-emulsion system. Nanoscaled spherical silicas were prepared by Stöber method via deposition on the surface of micron calcium carbonate. Scanning- and transmission-electron microscopic analysis confirmed a micro-/nano-complex structure, enabling the composite material coating possessed coarser surface similar to those of ‘lotus leaf’. After modification with 1 H, 1 H, 2 H, 2 H-perfluorodecanethiol, both good super hydrophobicity and good fluorescent performance were confirmed by the water contact angle of 154.1°±1.5°, their surface-free energy, and fluorescence quantum yield of 14.1%, which provides an inexpensive and easy way to fabricate superhydrophobic material with fluorescence characteristics and promotes high value application of inorganic materials.