Measuring the specific surface area of monolayer graphene oxide in water

Many applications of graphene oxide concern specific surface area. Monolayer graphene has a high specific surface area of about 2630 m(2)/g, but the specific surface area of monolayer graphene oxide reported in literature (usually 2-1000 m(2)/g) is much smaller. To date, the exact measurement of the specific surface area of monolayer graphene oxide still remains a challenge. Here we demonstrate that this specific surface area can be measured in water by a rheology-based method. Graphene oxide was fully exfoliated in water to obtain monolayer graphene oxide/water solutions. Its specific surface area was theoretically calculated to be about 2418 m(2)/g, and was measured to be approximately 2391 (+/- 1292) m(2)/g. The measured value is obviously larger than those in literature, and is close to the theoretical value. The advantages and disadvantages of this new method have been discussed. (C) 2019 Elsevier B.V. All rights reserved.