Graphene-tin oxide composite nanomaterials incorporated sulfonated polyether ether ketone for proton exchange membrane fuel cell

The PEEK was sulfonated via electrophilic substitution by treating it with concentrated sulfuric acid (98%), resulting in the introduction of sulfonic acid groups (–SO₃H) onto the polymer backbone. Graphene nanosheets (GNS) and tin oxide (SnO₂) nanoparticles were synthesized via a hydrothermal method, leveraging their efficacy as radical scavengers. The GNS/SnO₂ materials were then incorporated into a SPEEK polymer matrix, resulting in the composite membranes with superior proton conductivity and greater durability, owing to the combined effects of the GNS/SnO₂ integration. In addition, the membranes were evaluated for their physicochemical, thermal, and mechanical characteristics, along with their proton conductivity. Under the conditions of 80°C and 95% of relative humidity, the proton conductivity of the 1 wt.% GNS/SnO₂@SPEEK nanocomposite membrane was 0.196 S/cm, surpassing the pristine SPEEK membrane, which recorded a lower value of 0.102 S/cm.The membrane strength was assessed through the oxidative stability tests, revealing that the 1 wt.% GNS/SnO₂@SPEEK membrane outperformed the unmodified membrane. These impressive properties highlight the potential of GNS/SnO₂-based PEMs as the promising candidates for the next-generation PEMFC technologies.