2018 - Sustainable Industrial Processing Summit & Exhibition
4-7 November 2018, Rio Othon Palace, Rio De Janeiro, Brazil
| Preparation of Graphene Nanosheets by Shock Waves Pengwan Chen1; Xin Gao1; Hao Yin2; Chunxiao Xu1; Qiang Zhou1; 1BEIJING INSTITUTE OF TECHNOLOGY, Beijing, China; 2INSTITUTE OF SYSTEMS ENGINEERING, CHINA ACADEMY OF ENGINEERING PHYSICS, Mianyang, China; PAPER: 159/Manufacturing/Regular (Oral) SCHEDULED: 16:20/Tue./Sao Conrado (50/2nd) ABSTRACT: Shock wave action of high temperature, high pressure and high strain rate lasting for very short time (~10<sup>-6</sup> s) will cause a series of catastrophic changes of material chemical and physical properties, and herein both detonation-driven high velocity flyer impact loading and electrical explosion technique were employed to induce shock wave for the synthesis of high-quality graphene materials. Using solid CO<sub>2</sub> (dry ice) as the carbon source [1], few layer graphene nanosheets were successfully synthesized by reduction of CO<sub>2</sub> with calcium hydride through detonation-driven flyer impact. Furthermore, by adding ammonium nitrate to the reaction system, nitrogen-doped graphene materials were formed in this one-step shock-wave treatment. Similarly, a few layers of graphene and nitrogen-doped graphene materials were also prepared through the reaction of calcium carbonate and magnesium [2], and the shock pressure and temperature are two important factors affecting the synthesis of few layer graphene nanosheets. Besides that, electrical explosion exfoliation of crystalline flake graphite suspension was achieved to synthesize graphene sheets. Meanwhile, graphite nanosheets, few-layer graphene, and especially, mono-layer graphene with good crystallinity were also produced by electrical explosion of high-purity graphite sticks in distilled water at room temperature [3]. Delicate control of energy injection is critical for graphene nanosheets formation, whereas mono-layer graphene was produced under the charging voltage of 22.5-23.5 kV. The recovered samples were characterized using various techniques such as transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, atomic force microscope, and X-ray photoelectron spectroscopy. Therein, the nitrogen-doped graphene was demonstrated to act as a metal-free electrode with an efficient electrocatalytic activity toward oxygen reduction reaction in alkaline solution. This work provides a simple but innovative route for producing graphene nanosheets. References: [1] P. Chen, C. Xu, H. Yin, X. Gao, L. Qu, Carbon 115 (2017) 471-476. [2] H. Yin, P. Chen, C. Xu, X. Gao, Q. Zhou, Y. Zhao, L. Qu, Carbon 94 (2015) 928-935. [3] X. Gao, C. Xu, H. Yin, X. Wang, Q. Song, P. Chen, Nanoscale 9 (2017) 10639-10646. |
