A study of inter-step stirring effects on the thickness and yield of graphene oxide prepared through an improved Hummers method

We report graphene oxide (GO) preparation from graphite powder through two different and improved versions of Hummers method. For the first method, we replicated the work already reported by T. Wu et al. In the second method, we followed the same procedure but with stirring intervals in between consecutive process steps. We call these intervals as inter-step stirring intervals. For the inter-step stirring method, X-ray diffraction (XRD), Fourier transform-infrared (FTIR) spectroscopy and titration analyses were conducted to understand the structure and chemistry of the prepared GO. Scanning electron microscopy (SEM) studies were made to reveal the surface coverage feature of GO deposited from very dilute aqueous dispersion of GO, through drop casting. For thickness measurements, randomly selected GO nanosheets, obtained from both the methods, were analyzed through atomic force microscopy (AFM). We came up with the appealing finding that inter-step stirring method was responsible for the development of few-layer GO with sheets as thin as 1.17 nm. Compared to the method without inter-step stirring, this method was responsible for a 38 % reduction in sheet thickness and a 2.46% increment in yield.