A Green Method for Graphite Exfoliation Using a Mechanochemical Route

Abstract

In the present work, we proposed a method to manufacture exfoliated graphene. This method is low cost and environmentally friendly by mechanochemical means and avoids the use of highly corrosive and dangerous reagents. Our raw material consists of natural graphite and sodium carbonate. The mix is milled followed by a citric acid treatment used as defoliation agents. The mixture consists of an equiatomic mix of graphite and sodium carbonate that is processed in a high-energy ball mill. The milled and raw mixtures are leached with an aqueous acid solution, hot refluxed, washed, and overnight dried. Observed morphological and chemical evidence exhibits a notable reduction of particle size with an important increased level of defoliation that improved the surface area values.

Sustainable Synthesis of High-Surface-Area Graphite Oxide via Dry Ball Milling

“…The starting material (Figure a, SEM and TEM) consisted of flakes. Micrographs revealed a change in the sample morphology after ball milling. − Figure c–f of SEM shows a significant reduction of the particle size after ball milling. Figure c–g of TEM depicts the irregular and stacked layered of the milled samples which are characteristic of graphite oxide as stated in Ma et al and Mhamane et al The graphite structure changed as a result of the graphite layers sliding due to the impact forces from ball collisions .…”

“…Micrographs revealed a change in the sample morphology after ball milling. − Figure c–f of SEM shows a significant reduction of the particle size after ball milling. Figure c–g of TEM depicts the irregular and stacked layered of the milled samples which are characteristic of graphite oxide as stated in Ma et al and Mhamane et al The graphite structure changed as a result of the graphite layers sliding due to the impact forces from ball collisions . For instance, SEM of graphite milled under 0.3 MPa nitrogen for 24 h at 150 min –1 (ball-to-powder-ratio: 132:1, stainless steel) confirmed the absence of flake-like structures and, instead, showed irregular sphere-like particles with a broad particle size distribution .…”

“…Figure 2c−g of TEM depicts the irregular and stacked layered of the milled samples which are characteristic of graphite oxide as stated in Ma et al 39 and Mhamane et al 40 The graphite structure changed as a result of the graphite layers sliding due to the impact forces from ball collisions. 38 For instance, SEM of graphite milled under 0.3 MPa nitrogen for 24 h at 150 min −1 (ball-to-powderratio: 132:1, stainless steel) confirmed the absence of flake-like structures and, instead, showed irregular sphere-like particles with a broad particle size distribution. 36 Furthermore, Energy dispersive X-ray spectroscope (EDX) measurements were conducted for all the studied materials (Figure 3).…”