A one-pot strategy for highly efficient preparation of ultra-large graphene oxide

Ultra-large graphene oxide (ULGO) is highly demanded in many graphene-based applications requiring high performance. However, existing methods generally rely on environmentally unfriendly systems, energy-intensive processes, or time-consuming steps to increase size, leaving much room for improvement in both size and preparation efficiency. Herein, we realize the fast fabrication of ULGO directly from graphite by integrating graphite expansion and the following oxidation into one specially designed wet chemical pot. This one-pot strategy shortens the total expansion-oxidation time by up to a third of the most efficient method reported before and enables a record large size of 109.7 μm (on average). Mechanism investigation reveals that uniform expansion is the key to ensuring large size, based on which larger ULGO (up to 120.1 μm) is prepared by appropriately extending the expansion time. Moreover, films assembled from the ULGO exhibit a Young's modulus (20.1 GPa) superior to most reports and a tensile strength (229.3 MPa) 26.0% larger than the best report. This one-pot expansion-oxidation as a new strategy brings the size of ULGO and its preparation efficiency to a new level, which is expected to greatly facilitate the construction of high-performance graphene macrostructures and their applications in many high-end fields.