Revealing the atomistic structure of carbon nanomembranes: molecular dynamics simulations and experiments with highly charged ions

Abstract

Carbon nanomembranes (CNMs) are a new class of near-2D membranes with potential applications ranging from energy storage and generation, through to water filtration. It has recently been shown that highly-charged ions can be used to introduce additional nanoscale pores to these membranes, where the pore diameters can be controlled by varying the kinetic and potential energy (incident charge state) of the impinging ions [1,2]. Additionally, when these transmitted ions interact with CNM, or indeed any thin material, they carry with them information about the original structure which can then be extracted by interrogating the resultant distribution of final ion charge states [3]. Here, we use a coupled experimental and simulation approach to identify candidate atomistic structures of a typical CNM, from those generated via liquid-quench and annealing molecular dynamics simulations. Experimental and simulated ion charge exchange data suggest that CNMs have an innate sub-nanometer porous structure. Furthermore, these membranes may have an under-coordinated carbon network that would be stabilised when exposed to atmospheric conditions. The candidate CNM structures identified will also be valuable for future computational studies, e.g. elucidating the mechanism of water and gas permeation. Our results shed new light on the atomistic structure of CNMs.