Chiral nematic porous germania and germanium/carbon films

Abstract

We report our extensive attempts and, ultimately, success to produce crack-free, chiral nematic GeO₂/cellulose nanocrystal (CNC) composite films with tunable photonic properties from the controlled assembly of germanium(IV) alkoxides with the lyotropic liquid-crystalline CNCs in a mixed solvent of water/DMF. With different pyrolysis conditions, the photonic GeO₂/CNC composites can be converted into freestanding chiral nematic films of amorphous GeO₂, and semiconducting mesoporous GeO₂/C and Ge/C replicas. These new materials are promising for chiral separation, enantioselective adsorption, catalysis, sensing, optoelectronics, and lithium ion batteries. Furthermore, the new, reproducible synthesis strategies developed may be applicable for constructing other composites and porous materials with chiral nematic ordering.