Scientists from the Institute of Physical Problems named after F. V. Lukin in Zelenograd, Russian Federation, discovered a previously unknown 3D nanostructure consisting of graphene sheets. The discovered nanostructure is a multilayer system of parallel hollow channels with quadrangular cross-section extending along the surface.
The thickness of the channel walls/facets of the nanostructure is about 1 nm, the width of the channel facets is approximately 25 nm, and the channel length reaches at least several hundreds of nanometers. This discovered nanostructure looks so extraordinary that it took some time to understand what it actually is. The structure was dramatically different from whatever had previously been observed on graphite.
After performing additional measurements and analysis of the images, it became clear that this was a system of hollow nanosized channels extending along the surface with wall thickness less than 1 nm. The estimated value of thickness as well as the quadrangular cross-section of the channels indicate that the channel walls/facets are graphene planes. After clarifying the geometry and sizes of the discovered objects, the scientists set out to understand how they had been formed. Several hypotheses were suggested, but none was decidedly accepted. Finally, a rather simple solution was found, which is based on a series of mechanical deformations of graphite, which is layered by nature.
In short, it appears that this is the formation mechanism: during graphite cleavage, a compressive stress directed along the surface appears in the thin surface layer. As the cleaving front moves on, the compressive stress causes, first, elastic bending of this layer at a small section, and then plastic deformation of the layer with its simultaneous splitting into graphene sublayers. The last two transformations result in a nanofold formation. At the final stage, the split graphene sublayers slide in the nanofolds relative to each other resulting in formation of the nanochannels arranged in stacked layers.
Since the nanochannels have a quadrangular cross-section, the detected graphene nanostructure has been named box-shaped. The box-shaped graphene (BSG) nanostructure contained so many interesting features that just three STM scans were enough to make substantial conclusions about the structure and its main parameters.
Even the preliminary analysis of the BSG nanostructure has shown good prospects of its use in various devices. Here are some of the possible applications: ultra-sensitive detectors; high-performance catalytic cells; nanochannels of microfluidic devices (molecular sieving, DNA sequencing and manipulation); high-performance heat sinking surfaces; rechargeable batteries of enhanced performance; nanomechanical resonators; electron multiplication channels in emission nanoelectronic devices; high-capacity sorbents for safe hydrogen storage.