Microwave-assisted fabrication of slight-expanded graphite under normal temperature

Different from traditional expanded graphite, novel slight-expanded graphite with only four times expansion was produced. The preparation method presented here includes an improved Hummers method to change the natural flake graphite to graphite oxide by using lower amounts of concentrated sulfuric acid and concentrated phosphoric acid. Then, the graphite oxide is expanded via microwave irradiation instead of temperature increase. Scanning electron microscope images and X-ray diffraction patterns show that the lamellar structure of natural graphite was changed to a complex, overlapped, curled-up structure in the slight-expanded graphite.