• graphene oxide;
  • graphene;
  • l-ascorbic acid;
  • reducing ability;
  • solution-chemical method

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 sp2 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