A facile one-pot route for preparing cellulose nanocrystal/zinc oxide nanohybrids with high antibacterial and photocatalytic activity

Cellulose nanocrystal/zinc oxide (CNC/ZnO) nanohybrids were prepared through citric acid/hydrochloric acid hydrolysis of commercial microcrystalline cellulose (MCC), and simple precipitation with zinc nitrate aqueous solution [Zn(NO₃)₂·6H₂O] via one-pot green synthesis, in which preparation and modification of CNCs were performed simultaneously and the obtained CNCs with carboxyl groups could act as a stabilizing and supporting agent to anchor ZnO nanoparticles. The influence of the Zn²⁺ ion concentration on the morphology, microstructure, and properties of the CNC/ZnO nanohybrids was investigated by using Fourier-transform infrared and ultraviolet–visible (UV–Vis) spectroscopy, X-ray diffraction (XRD) analysis, field-emission scanning electron microscopy, and thermogravimetric analysis. According to the UV–Vis and XRD results, well-dispersed ZnO nanoparticles with hexagonal wurtzite structure and smallest average diameter of 42.6 nm were successfully anchored onto the surface of the CNCs. The CNC/ZnO nanohybrid CNC/ZnO-0.5 showed improved thermal stability, high antibacterial activity, and photocatalytic activity for methylene blue (MB) due to strong interaction between the CNCs and ZnO nanoparticles. Compared to CNCs, the thermal degradation onset temperature (T ₀) of the nanohybrids was increased by 23.9 °C, while antibacterial ratios of 100.0 and 100.0 % against viable Escherichia coli and Staphylococcus aureus were achieved. Moreover, 93 % of MB dye was decomposed after UV light irradiation for 100 min.