The exfoliation for few layers of graphene was prospective for scale output due to low cost and processable advantages. However, the massive production had some obstacles such as high pollution with organics and harmful elements and use of rare metal. Herein, we developed a facile and eco‐friendly expansion‐reduction exfoliation method to prepare graphene from graphene oxide (GO) with aid of oxalic acid(H₂C₂O₄). The as‐exfoliated graphene nanosheets possessed a 10‐layered thickness and large lateral size of approximately 0.5 μm. As a prospective application, the as‐exfoliated graphene nanosheets were conducted as additive in the grease for the sake of antifriction and antiwear. The results showed that the friction reduction and wear resistant properties were improved by 35.8% and 32.8%, respectively. The friction reducing mechanism of graphene in grease was proposed due to forming a protective film.

中文翻译：

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油脂中环保型脱落石墨烯的制备及其摩擦学性能

由于低成本和可加工的优势，几层石墨烯的剥落有望实现规模生产。但是，大规模生产存在一些障碍，例如有机物和有害元素的高度污染以及稀有金属的使用。在此，我们开发了一种简便且环保的膨胀-还原剥落方法，以草酸（H ₂ C ₂ O ₄）为原料，从氧化石墨烯（GO）制备石墨烯）。剥落的石墨烯纳米片的厚度为10层，横向尺寸较大，约为0.5μm。作为一种潜在的应用，剥落的石墨烯纳米片作为润滑脂中的添加剂使用，以防摩擦和抗磨。结果表明，减摩性能和耐磨性能分别提高了35.8％和32.8％。由于形成保护膜，提出了石墨烯在润滑脂中的降低摩擦的机理。