▎ 摘　　要

In this article, we first report an ultralow temperature (-60 degrees C) synthesis of graphene oxide nanosheets (GONs), which is achieved via the reduction reaction of tetrachloroethylene (C2Cl4) and potassium in liquid ammonia solution at atmospheric pressure. The as-obtained multilayer GONs with a high quality exhibit a low C/O atomic ratio of approximately 2:1, indicating that GONs are rich in the oxygencontaining functional groups. In order to improve their adsorption property, GONs are reduced at 500 degrees C for 2 h in flowing N-2, which results in the successful preparation of graphene nanosheets (GNs) with a high C/O atomic ratio of approximately 32:1. GNs show high specific surface area (508 m(2)/g), high adsorption capacity (Q(e) = 148.36 mg/g, C-0 = 180 mg/L), and rapid adsorption rate (>96%, 10 min) of organic dye rhodamine B (RhB) from water, suggesting that GNs have potential environmental applications as alternatives to commercial materials in wastewater treatment for the removal of organic dye. Compared with the reported methods to prepare GONs, our techniques have attractive advantages, such as low reaction temperature and being friendly to environment. (C) 2014 Elsevier B.V. All rights reserved.