Theoretical study of collision dynamics of fullerenes on graphenylene and porous graphene membranes

Highlights

• High energy C60 molecules colliding with graphene, Porous Graphene and Graphenylene membranes are described.

• Fractures are dependent on membranes’ geometry, impact angle and energy.

• Low energy collisions may lead to chemisorption of C60 molecules on graphene.

• Possible membrane-projectile interactions are mapped into comprehensive graphical diagrams.

Abstract

A comparative study regarding the behavior of graphene, porous graphene and graphenylene monolayers under high energy impact is reported. Our results were obtained using a computational model constructed to perform investigations of the dynamics of high velocity fullerenes colliding with free standing sheets of those materials. We employed fully reactive molecular dynamics simulations in which the interatomic interactions were described using ReaxFF force field. During the simulations, free standing monolayers of the investigated materials were submitted to collision with a C60 fullerene molecule at impact angles within the range $0°\le \theta \le 75°$. We considered kinetic energies in the range $0eV\le E_k\le 1500eV$, that corresponds to a projectile velocity v in the range $0\AA /fs\le v\le 0.2\AA /fs$. Also, the failure dynamics of each one of the 2-dimensional materials is described in a comparative analysis in which relevant differences and unique features observed in the mechanical stress dissipation processes are highlighted. Finally, performing hundreds of simulations we were able to map many possible scenarios for these collisions and to construct diagrams that elucidate, for each one of the materials, the possible behaviors under the action of a highly energetic C60 projectile as a function of energy and incident angle.

Introduction

Graphene (Gr) is well known for its outstanding mechanical and electronic properties [1,2]. Some of its unique characteristics can be understood as the result of a combination between the 2-dimensional geometry, which brings quantum confinement effects, and the stability of the sp2 bonds that keeps the hexagonal lattice chemically stable and mechanically strong [3]. Due to its exceptional mechanical resistance, graphene is considered a promising candidate for ballistic protection. Indeed, several authors have already discussed and tested graphene under collision for many different conditions [[4], [5], [6], [7], [8], [9], [10], [11]]. Sadeghzadeh, S [12]. and Saitoh, S and Hayakawa, H [13] studied many relevant aspects for the understanding of graphene behavior when subjected to the action of nanoscaled projectiles. Collisions of gas molecules with graphene-based plates and restitution coefficients for different incident angles were investigated. Were also performed systematic comparisons demonstrating that graphene plates are clearly more resistant to damage caused by impacts than other materials, such as metal plates [12]. Also of importance for this field is the application of multiscale approach to characterize collision processes for single or multilayer systems when used as barriers against highly energetic projectiles [5,6]. In addition to the great interest in Graphene’s physical and chemical properties, it is also very important to investigate materials that are structurally related to it. An enormous variety of graphene-related materials were described in the last decades [[14], [15], [16], [17]] and some of these are quite interesting, as Graphenylene (also known as Biphenylene Carbon or BPC) and Porous Graphene (PG) [18,19], shown in Fig. 1 (a) and 1(b) respectively. Both materials are carbon-based and their geometries are based on the architecture of graphene, shown in Fig. 1-(c). To our best knowledge, there is a lack of works comparing graphene’s behavior with that observed for those two materials, despite the fact that they were both already experimentally obtained [18,20]. In this regard, our study aims to contribute to the field by providing a comparison between the cited materials and graphene under collision. Our study concentrates on highly energetic collisions, using a C60 molecule (shown in figure (1)-d) as the projectile. An extensive set of Molecular Dynamics (MD) simulations was carried in order to investigate the dynamics of collisions as well as to compare how these three materials are capable of propagating mechanical stress. For this end, many different initial conditions were studied to allow several analysis and comparisons of elastic and inelastic scattering of C60 molecules colliding with the monolayer sheets of graphene, graphenylene and porous graphene. The necessary conditions for obtaining elastic/inelastic scattering with or without structural damage to the projectile and/or the target membrane were determined for each material and will be discussed in detail throughout the paper. Also, we describe the failure process and the dynamics of stress distribution during collision in different conditions. The analysis and simulations presented in the paper were carried using the software LAMMPS [21]. For the description of inter-atomic interactions we adopted ReaxFF [22,23] potential which was used in many cases to study various carbon based materials and their properties, such as chemical adsorption or mechanical properties [[24], [25], [26], [27], [28], [29]]. A reactive methodology was already applied by Yoon et al. [30] in the study of heavy projectiles colliding with graphene. In that study the authors considered the effect of silica and nickel supersonic projectiles colliding with graphene sheets. Were described the formations of 5-member and 7-member rings as well as patterns for crack formation which were studied in conjunction with the penetration energy dependence. In another study of interest, Lin et al. [31] simulate the collision of small molecules with a layer of CH4 molecules adsorbed on graphene and study the angular dependency of energy barriers for displacing one methane molecule. Additionally, they were able to determine what molecules would be more efficient for this effect. On the other hand, in the simulations presented in our work, the discussion will focus on setups in which the projectile is always the same, an almost round and relatively big molecule, namely a C60 fullerene. The variation in our setups will be provided by the target, not the projectile like in the case of Lin and collaborators study [31]. In the case of the present study, in order to avoid possible methodological artifacts in our results, we carried supplementary simulations for some of our representative setups adopting another interatomic potential, namely the Airebo [32], which is a well established reactive potential conceived to describe carbon based systems. The Airebo results are compared against ReaxFF to demonstrate the consistency of our study and to confirm the physical significance of the trends identified and discussed in the results section.