Contents lists available at ScienceDirect Ceramics International journal homepage: www.elsevier.com/locate/ceramint Production of few-layer graphene by wet media milling using organic solvents and different types of graphite Sergio Mancillas-Salas a , Joaquín Barroso-Flores b,d , Rafael Villaurrutia c , Verónica García-Montalvo d , Eddie López-Honorato a,* a Centro de Investigación y de Estudios Avanzados del IPN, Unidad Saltillo, AV. Industria Metalúrgica 1062, Ramos Arizpe, 25900, Mexico b Centro Conjunto de Investigación en Química Sustentable UAEM – UNAM Personal de La UNAM Carr, Toluca – Atlacomulco Km 14.5, Toluca de Lerdo, Estado de México CP, 50200, Mexico c Thermofisher Scientific, Insurgentes Sur 863, Ciudad de México, 03810, Mexico d Instituto de Química. Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, CD. MX., 04510, Mexico ARTICLE INFO Keywords: Graphite layers Mechanical milling Ultrasonic processing Graphene ABSTRACT One of the main challenges in the exploitation of nanomaterials is their production at low cost. Mechanical milling is an alternative for the production of nanomaterials, such as graphene. In this work we have studied the effect of different solvents (methanol, ethanol, acetone, hexane, toluene and xylene) on the production of gra- phene by attrition milling of graphite. Among the solvents tested, methanol showed to be able to produce graphene sheets more efficiently. Computer modeling suggests that although methanol and acetone have a weaker interaction with graphene (3.95 and 7.41 kcal/mol, respectively) compared to xylene (12.73 kcal/mol), they have a higher Gibbs free energy (6.46, 3.81 and 0.33 kcal/mol for methanol, acetone and xylene, respec- tively), suggesting a higher mobility on its surface, thus facilitating the exfoliation of graphene. The production of graphene was corroborated by Raman spectroscopy and transmission electron microscopy, showing to be a few layers graphene (< 5 layers), approximately 1–6 μm in length, with a high degree of graphitization. Additionally, we also show that through this route is feasible to produce a few-layer graphene using synthetic and amorphous graphite as more economical alternatives. 1. Introduction Graphene is a two-dimensional (2D) material formed by carbon sp 2 hybridized atoms, packed in a honeycomb lattice that highlights its thermal, mechanical and electrical properties due to its sp 2 π-conjuga- tion [1,2]. Graphene has found a wide range of applications in energy generation, storage, biomedical applications and environmental re- mediation [1,3,4]. However, one of the main challenges on the appli- cation of this material is the production of graphene in large volumes and through a cost-effective process. Several routes exist to produce graphene, however, most of them are expensive (such as chemical vapor deposition) or lead to the production of large volumes of by-products, such as the reduction of graphene oxide produced by the Hummers' method [5]. Mechanical milling is a widely used technique to reduce the particle size of a wide variety of pristine materials [6,7] and has been used to produce graphene-like nanomaterials in combination with different solvents. For example, Zhao et al. tested different solvents in the mechanical exfoliation of graphite nanosheets, obtaining larger gra- phene fractions in solvents like dimethylformamide (DFM) and N-me- thylpyrrolidone (NMP) [8]. The production of multilayered graphene has also been reported by Kun et al., observing that the process was better achieved in ethanol than in deionized water [9]. Additionally, using NMP, cyclohexanone and i-propanol, Damm et al. were able to obtain few-layered graphene suspensions, being NMP the solvent who produced graphene with the highest concentration [10]. Furthermore, although Zhao [8] and Damm [10] were able to produce graphene by mechanical milling, their starting material varied using expanded and isostatic graphite. Even though mechanical exfoliation of graphite for graphene pro- duction has been previously reported, the capacity of traditional sol- vents such as methanol, ethanol, acetone, etc. for the production of graphene is not well understood. In this paper we employ natural graphite flakes, synthetic graphite and amorphous graphite to study the effect of methanol, ethanol, acetone, hexane, toluene and xylene on the mechanical milling and the production of graphene. We show that it is https://doi.org/10.1016/j.ceramint.2019.09.235 Received 5 August 2019; Received in revised form 19 September 2019; Accepted 23 September 2019 * Corresponding author. E-mail address: eddie.lopez@cinvestav.edu.mx (E. López-Honorato). Ceramics International xxx (xxxx) xxx–xxx 0272-8842/ © 2019 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Please cite this article as: Sergio Mancillas-Salas, et al., Ceramics International, https://doi.org/10.1016/j.ceramint.2019.09.235