Graphene Nanopores

Abstract

Graphene is a two-dimensional, atomic thin, usually impermeable nanomaterial with astonishing electrical, magnetic and mechanical properties and can therefore at its own right be found in applications as sensors, energy storage or reinforcement in composite materials. By introducing nanoscale pores graphene alter and extend its properties beyond permeability. Graphene then resembles a nanoporous sensor, a nanoporous, atomic thin membrane which opens up for such varied applications such as water purification, industrial waste water treatment, mineral recovery, analytical chemistry separation, molecular size exclusion and supramolecular separations. Due to its nanoscopic size it can serve as nanofilters for ion separation even at ultralow nano- or picomolar concentrations. It is an obvious choice for DNA translocation, reading of the sequence of nucleotides in a DNA molecule, and other single molecular analyses as well for biomedical nanoscopic devices since dimensions of conventional membranes does not suffice in those applications. Even though graphene nanopores are known to be unstable against filling by carbon adatoms they can be stabilized by dangling bond bridging via impurity or foreign atoms resulting in a robust nanoporous material. Finally, graphene’s already exceptional electronic properties, its charge carriers exhibit an unusual high mobility and ballistic transport even at 300 K, can be made even more favorable by the presence of nanopores; the semimetallic graphene turns into a semiconductor. In the pores, semiconductor bands with an energy gap of one electron volt coexist with localized states. This may enable applications such as nanoscopic transistors.

Graphene: A future science material for water treatment

“…Of course, graphene oxide gives better results as compared to pure graphene in the water filtration process [73][74][75]. Generally, the diameter of pores in graphene oxide is found approximately 5.0 Å [156], which is prolonged to 9 Å [157] on hydration, consequently, the molecules with the size of 4.5 Å [158] can also pass, while molecules with a size greater than this are prevented [159]. There are many methods for the preparation of nanosheets based on graphene oxide such as layer-by-layer deposition, vacuum filtration, spin coating, dropcasting, etc.…”