Comparative methods for reduction and sulfonation of graphene oxide for fuel cell electrode applications

Abstract

Abstract Graphene oxide (GO) was synthetized, reduced and further sulfonated for the preparation of electrodes. GO was obtained using modified Hummer's method from graphite flakes. The partial reduction of graphene oxide (rGO) was performed by chemical and thermal process and subsequently functionalized using sulfuric acid or aryl diazonium salt of sulfanilic acid as sulfonating agents to afford rGO-SO3H. The influence of the reduction processes on the sulfonation reactions of rGO was evaluated through XRD, TGA, FT-IR and Raman techniques. Electrochemical properties of both rGO and sulfonated rGO materials as modified glassy carbon electrode were evaluated using a K3FeCN6 solution as a reference redox system. XRD confirmed the partial reduction of GO by two methods and FT-IR demonstrated that SO3H groups were successfully grafted on GO. VC results confirmed that both reduction and sulfonated methods leads to a better material with superior electrochemical properties compared to GO and rGO. Thermally reduced GO and functionalized with sulfuric acid [rGOT-SO3H(1)] showed the best electron transfer activity compared to those chemically reduced or sulfonated with sulfanilic acid. The electrochemical properties observed for rGOT-SO3H(1) suggest than can be a suitable support material of nanoparticles for the preparation of electrodes for fuel cells applications.