An efficient and eco‐friendly solution‐chemical route for preparation of ultrastable reduced graphene oxide suspensions

We describe a facile and eco‐friendly solution approach to chemically reduce graphene oxide (GO) to high‐quality graphene using nontoxic inexpensive reductants. The reduction process and mechanism of a group of eco‐friendly reductants were systematically studied. These reductants perform quite differently in terms of reduction rate ( l ‐ascorbic acid [ l ‐AA] >  d ‐fructose > sucrose > glucose > sodium sulfite), density of small sp 2 domains ( l ‐AA > sodium sulfite > glucose > sucrose >  d ‐fructose), degree of reduction ( l ‐AA > glucose >  d ‐fructose > sodium sulfite > sucrose), and stability of the reduced GO suspension ( l ‐AA >  d ‐fructose > sucrose > glucose > sodium sulfite). l ‐AA shows the highest reducing ability, achieving the largest extent of reduction after 10 min in the presence of ammonia. Both residual oxygen functionalities and the adsorbed oxidization products of l ‐AA on the graphene surface are responsible for stabilizing the reduced GO suspension over several months. © 2014 American Institute of Chemical Engineers AIChE J , 60: 2757–2764, 2014