Synthesis and characterization of triazole based sulfonated nanocrystalline cellulose proton conductor

Abstract: Polymer electrolyte membrane fuel cells operated at temperature above 100 °C has enhanced electrochemical reactions; reduce CO poisoning, lower electrocatalyst loading and good water management. Nafion, the commercial proton exchange membrane performs poorly at this temperature, necessitating synthesis of alternative membranes. Nanocrystalline cellulose (NCC) based membrane promises a better performance at high temperature due to its water retention capability. Herein, sulfonated NCC composite membrane doped with 1,2,4-triazole was synthesized using solution casting technique. Findings have shown that the synergistic effect of the sulfonic acid group and the 1,2,4-triazole yields high proton conductivity of 13 mScm⁻¹ at 120 °C for NCC-poly vinyl alcohol-triazole5 (NCC-PVA-T5) composite membrane. The membranes were characterized with thermogravimetric analysis, fourier transform infrared spectroscopy, X-ray diffraction, electrochemical impedance spectroscopy, scanning electron microscopy and mechanical test to unravel the effect of the 1,2,4-triazole on the sulfonated NCC composite membranes. The elemental analysis of the membranes was also carried out to reveal the presence of triazole in the final membrane composites. Graphic abstract: [Figure not available: see fulltext.].