We have produced ultrathin epitaxial graphite films which show remarkable 2D electron gas (2DEG) behavior. The films, composed of typically 3 graphene sheets, were grown by thermal decomposition on the (0001) surface of 6H-SiC, and characterized by surface-science techniques. The low-temperature conductance spans a range of localization regimes according to the structural state (square resistance 1.5 kOhm to 225 kOhm at 4 K, with positive magnetoconductance). Low resistance samples show characteristics of weak-localization in two dimensions, from which we estimate elastic and inelastic mean free paths. At low field, the Hall resistance is linear up to 4.5 T, which is well-explained by n-type carriers of density 10^{12} cm^{-2} per graphene sheet. The most highly-ordered sample exhibits Shubnikov - de Haas oscillations which correspond to nonlinearities observed in the Hall resistance, indicating a potential new quantum Hall system. We show that the high-mobility films can be patterned via conventional lithographic techniques, and we demonstrate modulation of the film conductance using a top-gate electrode. These key elements suggest electronic device applications based on nano-patterned epitaxial graphene (NPEG), with the potential for large-scale integration.

Ultrathin epitaxial graphite: 2D electron gas properties and a route toward graphene-based nanoelectronics

Abstract In recent years, with the higher requirements for the performance of cement-based materials and the call for energy conservation and environmental protection, a wave of research on new materials has set off, and various high-performance concrete and more environmentally friendly geopolymers have appeared in the public. With a view to solving the defects of energy consumption, environmental protection and low toughness of traditional cement-based materials. At the same time, nanomaterials have become a focus of current research. Therefore, the research on the properties of cement-based materials and geopolymers modified by graphene and its derivatives has aroused extensive interest of researchers. Graphene-based nanomaterials are one of them. Because of their large specific surface area, excellent physical properties have been favored by many researchers. This paper reviews the research progress of graphene-based nanomaterials in improving the properties of cement-based materials and geopolymer materials, and points out the main challenges and development prospects of such materials in the construction field in the future.

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Review on the research progress of cement-based and geopolymer materials modified by graphene and graphene oxide

An intensive review on the role of graphene oxide in cement-based materials

Presently, the construction industries worldwide are looking for materials with low carbon footprint and environment friendliness. Yet, ordinary Portland cements (OPC) based materials are widely used in building sectors and remain majorly responsible for carbon pollution. The deterioration that happens in such concretes from the very beginning of the service not only life reduces their lifespan but also demands more OPC. Furthermore, the continuation and repairing are mostly laboured intensive and too expensive. Thus, self-recovery of the damaged concretes is significant concerning environmental mitigation and energy saving. Lately, nanomaterials based concretes have been exploited diversely in the construction engineering owing to their enhanced mechanical and durable attributes. The design as well as production of self-healing and sustainable concrete is an intensely research topic in nanotechnology. In this view, this article provides a comprehensive assessment on nanomaterials based self-healing concretes. The past development, recent trends, environmental impact, sustainability, merits and demerits of several methods of self-healing concrete production are discussed.

Sustainability of nanomaterials based self-healing concrete: An all-inclusive insight

Graphene reinforced cement composites: A review

Graphene-based nanosheets for stronger and more durable concrete: A review

The interface properties between fiber and matrix predominantly influence the mechanical performance of fiber reinforced cementitious composites (FRCCs). In this study, the interface between polyvinyl alcohol (PVA) fibers and mortar was modified by coating graphene oxide (GO) on the fiber surface. Experimental results showed the GO@ PVA fibers improved the tensile strength of FRCCs by 35.6% compared to that of pristine PVA FRCCs. Theoretical analysis indicated this significant improvement was attributed to the enhancement of the chemical bond energy (Gd) at fiber/matrix interface. With GO surface modification, the Gd was increased more than 80 times, changing the failure mode at the interface from adhesive failure to cohesive failure.

Xupei Yao

Papers

Graphene-based nanosheets for stronger and more durable concrete: A review

Graphene oxide-coated Poly(vinyl alcohol) fibers for enhanced fiber-reinforced cementitious composites

Graphene-based modification on the interface in fibre reinforced cementitious composites for improving both strength and toughness

Effective strategies to realize high-performance graphene-reinforced cement composites

Graphene opens pathways to a carbon-neutral cement industry