To improve the proton conductivity of the proton exchange membranes (PEM), an amino derivative with sulfonic acid groups was used to modify graphene oxide (GO), resulting in sulfonated graphene oxide (S-GO), which was then incorporated into a perfluorinated sulfonic acid (PFSA) matrix to fabricate a PFSA/S-GO composite membranes. Elevating the doping concentration of S-GO within the composite membrane has resulted in enhanced proton conductivity, outperforming the baseline PFSA membrane across a range of temperatures. Notably, this conductivity ascended to 291.89 mS/cm when measured at 80 °C under conditions of 100% RH. Furthermore, the strong interface interaction between sulfonated graphene oxide and perfluorinated sulfonic acid polymer endowed the composite proton exchange membrane with excellent thermal stability and mechanical strength.

Sulfonated graphene oxide for proton exchange membranes with significantly enhanced proton conductivity
    Abstract
    1 Introduction
    2 Experimental section
        2.1 Materials
        2.2 Preparation of S-GO
        2.3 Preparation of PFSAS-GO composite membrane
        2.4 Characterization
        2.5 Water uptake (W.U.) and swelling ratio (S.R.)
        2.6 Proton conductivity and ion exchange capacity (IEC)
        2.7 Mechanical properties and thermal stability testing of membranes
    3 Results and discussion
        3.1 Structural characterization of S-GO
        3.2 Structural characterization of composite membranes
        3.3 Characterization of hydrophilicity of fillers and membranes
        3.4 IEC and proton conductivity of composite membranes
        3.5 Mechanical and thermal stability of PFSAS-GO composite membranes
    4 Conclusion
    Acknowledgements 
    References

• Shuyan Lin(College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061, Shandong, China)
• Yongxiang Wang(College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061, Shandong, China)
• Xiaokun Dong(College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061, Shandong, China)
• Jiangshan Gao(College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061, Shandong, China) Corresponding author
• Yan He(College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061, Shandong, China)
• Yongwen Cui(Shandong Dongyue Future Hydrogen Energy Materials Co., Ltd, Zibo 256400, Shandong, China)
• Hongxing Dou(Shandong Dongyue Future Hydrogen Energy Materials Co., Ltd, Zibo 256400, Shandong, China)
• Zhong Niu(Shandong Dongyue Future Hydrogen Energy Materials Co., Ltd, Zibo 256400, Shandong, China)
• Li Wang(Shandong Key Laboratory of Hydrogen Energy Advanced Materials & Technology, Zibo 256400, Shandong, China)