▎ 摘　　要

NOVELTY - Phosphonic acid-modified graphene oxide, is claimed. The phosphonic acid in phosphonic acid-modified graphene oxide is amino-containing phosphonic acid compounds. USE - The phosphonic acid-modified graphene oxide is useful in proton exchange membrane for fields of fuel cells and flow batteries (claimed). ADVANTAGE - The phosphonic acid-modified graphene oxide has reduces phosphoric acid doping level to below 10 and significantly increased proton conductivity of 9x 102S/cm; has lateral swelling rate of as low as 7% after immersing in phosphoric acid, and tensile strength exceeds 8MPa. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) benzimidazole polymer graft modified graphene oxide composite material, comprising benzimidazole polymer and phosphonic acid-modified graphene oxide; and (2) proton exchange membrane comprising the benzimidazole polymer grafted modified graphene oxide composite material, preferably the proton exchange membrane is also doped with phosphoric acid.