Properties of Graphene: A Theoretical Perspective

In this review, we provide an in-depth description of the physics of monolayer and bilayer graphene from a theorist's perspective. We discuss the physical properties of graphene in an external magnetic field, reflecting the chiral nature of the quasiparticles near the Dirac point with a Landau level at zero energy. We address the unique integer quantum Hall effects, the role of electron correlations, and the recent observation of the fractional quantum Hall effect in the monolayer graphene. The quantum Hall effect in bilayer graphene is fundamentally different from that of a monolayer, reflecting the unique band structure of this system. The theory of transport in the absence of an external magnetic field is discussed in detail, along with the role of disorder studied in various theoretical models. We highlight the differences and similarities between monolayer and bilayer graphene, and focus on thermodynamic properties such as the compressibility, the plasmon spectra, the weak localization correction, quantum Hall effect, and optical properties. Confinement of electrons in graphene is nontrivial due to Klein tunneling. We review various theoretical and experimental studies of quantum confined structures made from graphene. The band structure of graphene nanoribbons and the role of the sublattice symmetry, edge geometry and the size of the nanoribbon on the electronic and magnetic properties are very active areas of research, and a detailed review of these topics is presented. Also, the effects of substrate interactions, adsorbed atoms, lattice defects and doping on the band structure of finite-sized graphene systems are discussed. We also include a brief description of graphane -- gapped material obtained from graphene by attaching hydrogen atoms to each carbon atom in the lattice.Comment: 189 pages. submitted in Advances in Physic

Thermal transformation of end-of-life latex to valuable materials

Recent studies have demonstrated that carbon nanomaterials have huge potential in composite applications, but there is a continuous quest for identifying the most viable technique for producing this material. In this study, the possibility of using an innovative approach for the synthesis of value-added carbon nanomaterials and green gases from end-of-life soft mattress materials (latex) was investigated. Thermogravimetric analysis (TGA) was used to determine the thermal degradation of latex. Quantitative gas analysis at three different temperatures by infrared spectroscopy (IR) suggested that small gas molecules, especially CH4, could be produced at a higher temperature. The carbon residues produced after gas analysis were characterised by XRD, SEM, TEM, XPS, and Raman spectroscopy, suggesting the possibility of direct synthesis of carbon nanomaterials from waste latex. These carbon materials have Na, Zn, Si, and K in their structure, and further study is needed for understanding the effect of these elements on composite properties. Our study demonstrated that heat treatment of waste latex at 1000◦C for 15 min produced carbon materials, which contained 7–16% S and 1.2–2% N, and gases, such as CH4, could be synthesised