Graphene oxide (GO) has received great attention for its potential applications. The formation of large-size GO is favoured for its high mechanical properties and low structural defects. Improved Hummers' method is a commonly used method for GO synthesis. However, the production of large-size GO is often limited by the inevitable GO fragmentation caused by excessive oxidation and mechanical exfoliation. Here, we discovered that adding 1-pyrenebutyric acid (1-PBA) during the pre-treatment of graphite with sulfuric acid protects graphite from excessive oxidation and facilitates its self-exfoliation. Consequently, 99% monolayer GO with an average lateral size of 116 μm was obtained without external forces. Furthermore, X-ray photoelectron spectroscopy and Raman analyses showed that the large-size GO synthesized in the presence of 1-PBA has a high C/O ratio of 3.62 and low Raman I_D/I_G ratio of 0.83, so it has low structural defects. A mechanism of 1-PBA during GO synthesis was proposed. Moreover, we investigated the mechanical property of GO synthesized with 1-PBA and how the lateral size of GO affects the mechanical properties of GO films. Our results showed that the LGO film displayed the highest tensile strength (127 MPa) due to a denser, more aligned and compact structure than other GO films.

氧化石墨烯（GO）因其潜在的应用而备受关注。大尺寸GO的形成因其高机械性能和低结构缺陷而受到青睐。改进的 Hummers 方法是一种常用的 GO 合成方法。然而，大尺寸GO的生产往往受到过度氧化和机械剥落导致的不可避免的GO碎裂的限制。在这里，我们发现在用硫酸预处理石墨的过程中添加 1-芘丁酸 (1-PBA) 可以防止石墨过度氧化并促进其自剥落。因此，在没有外力的情况下获得了平均横向尺寸为 116 μm 的 99% 单层 GO。此外，_D /I _G比值为 0.83，因此具有较低的结构缺陷。提出了GO合成过程中1-PBA的机制。此外，我们研究了用 1-PBA 合成的 GO 的机械性能以及 GO 的横向尺寸如何影响 GO 薄膜的机械性能。我们的结果表明，由于比其他 GO 薄膜更致密、更对齐和更紧凑的结构，LGO 薄膜显示出最高的拉伸强度（127 MPa）。