Simultaneous synthesis of nanoporous zinc oxide and carbon dots via biopolymer dual templating

Dual templating is an effective strategy to create multiple inorganic functional materials with enhanced structural, optical, and biological properties. We demonstrate how biopolymer directly dictates the internal structure of zinc oxide. Here, a thermally degradable biopolymer, chitosan, is used as a structural template to produce internal nano pores of zinc oxide, while biopolymer transforms into highly luminescent carbon dots in the same solution. It is thought that zinc oxide is nucleated within the polymer network and continues to grow by engulfing the network into its crystalline structure. This is followed by thermal degradation of polymer template and its carbonisation into carbon dots. The synthesised porous zinc oxide-chitosan composites are characterised by PXRD, FT-IR, TGA, and SEM. The shape and size of pores created within zinc oxide crystals are assessed by FIB-SEM analysis. Finally, the antioxidant activity of the synthesised composites is significantly enhanced even at low concentrations from 20% in pure zinc-oxide to 100% in the synthesised composites.