State-of-the-art advancements in studies and applications of graphene: a comprehensive review

Graphene, originally observed under electron microscope in 1962 and rediscovered in 2004, is a newly emerging crystalline form of carbon. Known as the thinnest known material, graphene, a one-atom-thick and a Nobel Prize Winning material has outstanding mechanical, thermal, and electrical properties, making it one of the most sought-after materials in engineering domain. Owing to its peculiar and unconventional two-dimensional structure, it has unique linear energy bands which is very unusual as far as conventional parabolic energy bands of other materials are concerned. The two-dimensional structure of graphene is associated with a two-component wave-function (for triangular quantum-dots (TQD)), implication of which is the lattice symmetry which can be explained on the basis of Klein's paradox. This article presents the structural study and techniques for characterization of graphene. It is followed by the discussions on the rheological background which plays a crucial role in the study of graphene along with its electrical, mechanical, and thermal properties. A peculiar concept of second Piola-Kirchhoff stress is discussed. Subsequent discussions emphasize the synthesis methods for graphene. Finally, we present the applications of graphene in various indirect engineering domains like healthcare, use of graphene for ‘Toxicity Studies’. The widespread popularity of graphene is attributed to its excellent mechanical, thermal, and electrical properties, the result of which is its extensive use in numerous applications over the last decade, carbon nanotubes being the prominent example.