Novel siliceous mesoporous phosphotungstic acid embedded chitosan/LSMM polymer membrane for direct methanol fuel cells

•A CS/LSMM/mPTA-Si composite membrane was developed for DMFC applications, enhancing hydrophilicity, proton transport, and stability.•Optimal mPTA loading achieved a peak power density of 53.56 mWcm−2 at 121.4 mAcm−2.•Optimal DMFC performance was achieved using hot-pressing under 5 tonnes, 90 s, and 135 °C with the CS/LSMM/0.25mPTA-Si setup.•The membrane remained stable under 100% humidity despite minor swelling. Direct Methanol Fuel Cells (DMFCs) research focuses on improving Proton Exchange Membranes (PEMs) to enhance ion exchange and proton conduction. Although Nafion® is stable both chemically and thermally, however it suffers methanol crossover. In this study, a novel composite PEM was introduced by blending chitosan (CS), hydrophilic surface modifying macromolecules (LSMM), and mesoporous siliceous phosphotungstic acid (mPTA-Si) at varying loadings. Notably, the CS/LSMM membrane with 0.25 wt% of mPTA-Si content and optimized hot pressing technique conditions (5 tonnes, 90 s and 135 °C) exhibited superior performance, with a proton conductivity of 0.097 S/cm and a power density of 60 mW/cm2. Additionally, properties such as tensile strength and ion exchange capacity surpassed those of pure CS by 14 % and 56.12 %, respectively. The unique characteristics of CS, mPTA, and LSMM collectively contributed to the promising attributes of the CS/LSMM/0.25mPTA-Si membrane for enhancing fuel cell performance.