▎ 摘　　要

NOVELTY - Graphene oxide is dissolved in water, and uniformly stirred to obtain suspension of graphene oxide having concentration of 0.005-1 mol/L. The obtained graphene oxide suspension is added to nitric acid, heated to 80-88 degrees C, and cyanomethyl sulfate is added under controlled temperature of 120-130 degrees C. The resultant mixture is reacted for 3-5 hours, filtered and washed to obtain methanesulfonic acid/graphene material. USE - Preparation of methanesulfonic acid/graphene material for switch for optical sensor (all claimed). ADVANTAGE - The method efficiently provides methanesulfonic acid/graphene material by simple method, by simple method without affecting the environment. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) methanesulfonic acid/graphene material; (2) optical sensor switch; and (3) optical sensor.