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BACKGROUND: In this study, we have fabricated a polymeric material (CNC/Im) consisting of cellulose nanocrystals (CNC) synthesized from Vietnamese rice husk biomass and imidazole (Im) dopant. Next, we propose a new approach to fabricate Nafion/CNC/imidazole (NCI) composite materials by mixing the CNC/imidazole hybrid into Nafion matrix using a very simple solution method, and then investigating the influence of CNC/Im on the properties of NCI membranes. RESULTS: Electrochemical impedance spectroscopy (EIS) analysis showed that the proton conductivity of the CNC/Im membrane depends on the linked molar ratio of Im to glucose units (denoted by the n index), and this value is higher than that of pure CNC by a factor of 6. Differential thermal analysis (DSC) showed that the value of the n index is around 1:17 with all the content ratios between CNC and Im. Next, we synthesized composite materials based on CNC/Im and Nafion 117 (NCI) and investigated the influence of CNC/Im on the properties of NCI membranes. The results demonstrated that proton conductivity of the NCI membranes changes according to the content of Nafion 117, and reaches the highest value of 6.19 × 10 −4 S m -1 with an Nafion 117/(CNC/Im) ratio of 2:1. It was observed that the CNC fiber bundles were surrounded by a polymer layer and no phase separation occurs in the scanning electron micrographs of NCI materials.CONCLUSIONS: These results indicate that the prepared NCI composites will be potential materials for eco-friendly fuel cell operating in low humidity conditions.

Nanohybrids of zinc oxide/cellulose nanocrystals (ZnO/CNCs) were successfully prepared by using a low cost and green method for adsorption and photocatalytic degradation of methylene blue (MB). CNCs have been derived through the hydrolysis reaction by citric/hydrochloric acid from the pure cellulose isolated from Vietnamese Nypa fruticans trunk. The influence of the Zn2+ ion concentration on the morphology, microstructure, and thermal properties as well as the photocatalytic activity of the ZnO/CNC nanohybrids was investigated in detail. Analyses of FTIR spectra, XRD, and SEM indicated that the ZnO nanocrystals with the size of 50 nm formed and loaded on the surface of CNC. Based on the DRS spectra and the nitrogen adsorption–desorption isotherms (BET) analysis, the absorption of ultraviolet light with a strong absorption band around 400 nm was found for all the ZnO/CNC nanohybrids, and the values of specific surface areas (SBET) of materials can be controlled by changing the concentration ratio of Zn2+ ion and CNC. The TGA analysis demonstrated that the ZnO loading samples (ZnO/CNC) had the thermal degradation onset temperature higher than that of neat CNC. The effect of MB removal showed the results which were contributed not only by the adsorption ability of CNC but also by the photocatalytic activity of ZnO. The photocatalytic efficiency significantly depended on the content of ZnO loading. The maximum degradation of MB was about 95% in 150 min for the ZnO/CNC-1.0 sample in which the concentration ratio of zinc-precursor Zn(NO3)2·6H2O and CNC was 1.0.