Proton-Exchange Membrane Fuel-Cell Studies on Composite Films of Bi2S3 Microrod-Loaded Random Conjugated Copolymer Containing Carbazole and Diphenyl Sulfone

We synthesized a new random conjugated copolymer (RCCP) containing 2,6-bis(4-chlorophenyl)-4-phenylpyridine, carbazole, diphenylamine, and diphenyl sulfone. Subsequently, a Bi2S3-microrod-dispersed phosphoric-acid-doped random conjugated copolymer composite membrane was prepared and its properties were studied with respect to its suitability as a polymer electrolyte in fuel cells (PEMFCs). The monomer 2,6-bis(4-chlorophenyl)-4-phenylpyridine was successfully synthesized through the Hantsh pyridine synthesis. The RCCP polymer was effectively synthesized through the Friedel–Crafts reaction and characterized by Fourier transform infrared (FT-IR) spectroscopy, NMR spectroscopy, and scanning electron microscopy. Bi2S3 MRs were prepared by the hydrothermal technique, and transmission electron microscopy (TEM) and standard error of the mean (SEM) analyses revealed a rod-like morphology of Bi2S3. Neat RCCP and 1, 2, 3, and 5 wt % Bi2S3 microrod-embedded RCCP membranes were prepared and studied for their swelling ratio (SR), water uptake (WU), oxidative stability (OS), thermogravimetry (TGA), proton conductivity (PC), and ion-exchange capacity (IEC), and they exhibited tensile stress and elongation at break values of 2.08 MPa and 310.17%, respectively. The 3% Bi2S3 microrod-loaded RCCP membrane presented an ion-exchange capacity value of 1.117 mmol/g–1 and a proton conductivity of 1.74 × 10–2 S/cm–1 at 90 °C. The Arrhenius plot of proton conductivity with temperature showed that the proton transport in the Bi2S3/RCCP microcomposite films occurred by both vehicular and the Grotthuss mechanisms.