New architecture of 3D graphene with enhanced properties obtained by cold rolling

Abstract

Previously, we reported 3D Shaped 3D Graphene (3D2G) with controlled structural design. In this work, we introduced cold rolling as a post-processing technique to obtain compressed 3D2G, referred here as C3D2G, and investigated the relationship between its microstructure and properties. The performed comprehensive materials characterization of C3D2G revealed the micro-motion of the graphene flakes from their random orientations into a stacked and aligned structure along with the extrusion of bulk material into the structural pores which acted as stress-relief spaces. The obtained new bulk morphology significantly enhanced its properties. The achieved gravimetric density, electrical conductivity, and tensile strength of C3D2G were higher than 3D2G by 37.3, 53.4, and 24.9 times, respectively. A new process was demonstrated based on the observed extrusion enabling the welding of multiple pieces of 3D2G into one structure via cold rolling, thus showing potential for dimensional scaling up. The conducted tensile and electrical conductivity studies across the welded region revealed the presence of a mechanical bond within the joined area with a higher strength than the initial pieces involved in welding. Further, a unique application of this material was explored as a reusable, etch-resistant hard mask for patterning silicon wafers, and as a protective barrier against fluorine plasma environment. The etch rate measurements showed a higher etching resistance of C3D2G compared to Si and SiO2 when exposed to a fluorine plasma Reactive Ion Etching (RIE).