Nanoparticle Decorated Cellulose Nanocrystals (CNC) Composites for Energy, Catalysis, and Biomedical Applications

Decorating cellulose nanocrystals(CNC) with nanoparticles(NPs) allows to engineer novel CNC/NPs composites for advanced technologies and applications. NPs are well-known for their unique and highly efficient properties. However, NPs present challenges and limitations due to their aggregation, non-uniform growth, size distribution, and nanotoxicity. CNC surface overcomes most of these drawbacks by providing an attractive matrix/template to grow NPs of desirable morphology, distribution, and functionality. CNC has distinctive properties such as biodegradability, high surface area, low cost, good mechanical strength, surface functionality, and chiral nematic self-assembly. CNC/NPs composites combine the unique properties of both CNC and NPs. This review highlights the unique characteristics of CNC, NPs, and their composites for energy, catalysis, and biomedical applications. First, different production methods for CNC with their effect on morphology, crystallinity index, and yield are presented. Both organic and inorganic NPs are used to decorate either a pristine or a functionalized CNC surface. In situ nucleation and growth methods are compared with the direct incorporation of pre-formed NPs on the CNC surface. Applications of CNC/NPs composites are reviewed for energy storage material, conductive materials, catalysts, antibacterial agents, biosensors, and bioimaging. Finally, the current challenges and perspectives are presented for unleashing new possibilities in developing functional CNC-NPs composites.