Spectroscopic studies on reduced graphene oxide behaviour in multi-step thermal reduction

Graphene's excellent electrical, mechanical, thermal and optical properties make it one of the most desirable materials for diverse applications. Nevertheless, mass producing graphene has been a challenge since the first discovery in 2004. Here, we conducted a fast, green and safe method: multi-step thermal reduction (MSTR) process combining the use of commercial microwave and conventional furnace as the first and second steps, respectively to reduce graphene oxide (GO). Both steps used common tools in a short time to minimise investment. By evaluating several characterisation methods, we show that the first step partially reduces GO by decomposing most hydroxyls, creating a double interlayer spacing distance of 9.381 angstrom and 3.590 angstrom with retained hydrophilic property. Meanwhile, the second step further decomposes oxygen functional groups, recovers structural defects and creates a porous layered structure with an average interlayer spacing distance of 3.504 angstrom, 3.413 angstrom and 3.393 angstrom for temperatures of 500, 650 and 800 degrees C, respectively. In short, MSTR is a viable option to mass produce graphene-based material with desired properties.