Efficient Reduction of Graphite Oxide by Sodium Borohydride and Its Effect on Electrical Conductance

The conductivity of graphite oxide films is modulated using reducing agents. It is found that the sheet resistance of graphite oxide film reduced using sodium borohydride (NaBH4) is much lower than that of films reduced using hydrazine (N2H4). This is attributed to the formation of CN groups in the N2H4 case, which may act as donors compensating the hole carriers in reduced graphite oxide. In the case of NaBH4 reduction, the interlayer distance is first slightly expanded by the formation of intermediate boron oxide complexes and then contracted by the gradual removal of carbonyl and hydroxyl groups along with the boron oxide complexes. The fabricated conducting film comprising a NaBH4‐reduced graphite oxide reveals a sheet resistance comparable to that of dispersed graphene. Reduced graphite oxide films obtained using NaBH4 exhibit much lower sheet resistance than films obtained using N2H4 because the latter results in the formation of C–N groups, which may act as donors compensating the hole carriers in the film and increasing resistivity. A transparent conducting film prepared using optimized NaBH4 reduction reveals a sheet resistance comparable to that observed in dispersed graphene.