Preparation of highly stacked graphene papers via site-selective functionalization of graphene oxide†
Simple and effective preparation methods for highly stacked graphene papers are presented by site-selective functionalization of graphene oxides with di-functional small molecules, 1,4-butandiol and ethylenediamine. It was found that hydroxyl groups of 1,4-butandiol react mostly with edges of graphene oxides, while more reactive amine groups of ethylenediamine can react with carboxylic acid and epoxy groups on both edges and basal planes, which results in the interconnected graphene morphology in aqueous media. The graphene papers fabricated from the functionalized graphene oxide suspensions show a well stacked layer structure with a smaller interlayer distance than that of unmodified graphene oxide papers. Furthermore, high temperature annealing enhances the electrical conductivities of graphene papers fabricated from graphene sheets linked by ethylenediamine as high as 1716 S cm−1, due to the better stacked structure, further graphitization, and N-doping effects.