Fabrication of ternary composite based on imidazole, nafion, and cellulose nanocrystals for fuel cell application

In this study, we report a facile solution method to prepare a three-component composite membrane including imidazole, Nafion® 117, and cellulose nanocrystals (NCI). The structure and properties of NCI membrane were characterized by Fourier -Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD), Scanning electron microscopy (SEM), Energy Dispersive X-Ray Analysis (EDX), Thermogravimetric analysis (TGA), Differential scanning calorimetry (DSC), and Electrochemical impedance spectroscopy (EIS). The NCI composite membrane was capable of proton conductivity under low humidity conditions for applications in fuel cell field. EIS analysis showed that the proton conductivity of the NCI film depends on both imidazole and Nafion and this value was about 32 times higher than that of pure CNC. SEM results showed that the component phases in the NCI material structure had a good interaction and no phase separation was observed. In addition, the results of TGA also demonstrated that when having CNC dispersed in the structure of the composite material, it hinders the thermal movement of PTFE chains in Nafion, making these chains not decompose at high temperatures. This work shows that the NCI composite membrane can be optimized to serve as a proton-conducting solid film for fuel cells operating in low humidity conditions.