Superstructured Assembly of Nanocarbons: Fullerenes, Nanotubes, and Graphene

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

Iron oxide nanoparticles (NPs) hold great promise for future biomedical applications because of their magnetic properties as well as other intrinsic properties such as low toxicity, colloidal stability, and surface engineering capability. Numerous related studies on iron oxide NPs have been conducted. Recent progress in nanochemistry has enabled fine control over the size, crystallinity, uniformity, and surface properties of iron oxide NPs. This review examines various synthetic approaches and surface engineering strategies for preparing naked and functional iron oxide NPs with different physicochemical properties. Growing interest in designed and surface-engineered iron oxide NPs with multifunctionalities was explored in in vitro/in vivo biomedical applications, focusing on their combined roles in bioseparation, as a biosensor, targeted-drug delivery, MR contrast agents, and magnetic fluid hyperthermia. This review outlines the limitations of extant surface engineering strategies and several developing strategies that may overcome these limitations. This study also details the promising future directions of this active research field.

Designed synthesis and surface engineering strategies of magnetic iron oxide nanoparticles for biomedical applications

The mechanism and conditions for the phase transformations from α-Fe2O3 to Fe3O4 and Fe3O4 to γ-Fe2O3 nanoparticles have been investigated by the thermal analysis method. The morphologies and structures of various nanoparticles after annealing in H2 : Ar at 294 °C and in an O2 atmosphere at 302 °C have been examined and characterized. Finally, we confirmed that the monodisperse, porous and magnetic γ-Fe2O3 nanoparticles could be obtained by annealing the α-Fe2O3 nanoparticles synthesized by the hydrothermal route.

Structural evolution and characteristics of the phase transformations between α-Fe2O3, Fe3O4 and γ-Fe2O3 nanoparticles under reducing and oxidizing atmospheres

Among all polarizations, the interface polarization effect is the most effective, especially at high frequency. The design of various ferrite/iron interfaces can significantly enhance the materials’ dielectric loss ability at high frequency. This paper presents a simple method to generate ferrite/iron interfaces to enhance the microwave attenuation at high frequency. The ferrites were coated onto carbonyl iron and could be varied to ZnFe2O4, CoFe2O4, Fe3O4, and NiFe2O4. Due to the ferrite/iron interface inducing a stronger dielectric loss effect, all of these materials achieved broad effective frequency width at a coating layer as thin as 1.5 mm. In particular, an effective frequency width of 6.2 GHz could be gained from the Fe@NiFe2O4 composite.

Interface Strategy To Achieve Tunable High Frequency Attenuation

Building P-doped MoS2/g-C3N4 layered heterojunction with a dual-internal electric field for efficient photocatalytic sterilization

http://www.yicaige.com/upload/news/1398219434.pdf

Synthesis, optical and magnetic properties of α-Fe2O3 nanoparticles with various shapes

L-Cysteine capped Mo2C/Zn0.67Cd0.33S heterojunction with intimate covalent bonds enables efficient and stable H2-Releasing photocatalysis

The inferior separation efficiency of photo-induced carriers is still a major obstacle to the practical application of photocatalysts, whereas the spatial separation of reductive and oxidative components is expected to break through this bottleneck to promote charge separation and surface reaction kinetics. Herein, Mo2C nanosheets were employed to prepare a Mo2C/MoS2/In2S3 dual-heterojunction (a p–n junction of MoS2/In2S3 and a Schottky junction of Mo2C/In2S3) by one-pot solvothermal synthesis. Theoretical and experimental results proved that Mo2C acted as an electron transport “highway” and acceptor in Mo2C/MoS2/In2S3 dual-heterojunctions to expedite the spatial migration of electrons. Compared with In2S3 and MoS2/In2S3, the optimized Mo2C/MoS2/In2S3 composite exhibited significantly improved photocatalytic property, with the Cr(VI) reduction efficiency reaching 99.1% in 90 min under visible light irradiation. This study demonstrates that Mo2C may play a major role in an electron sink that can be used as a potential co-catalyst in multijunctional photocatalysts.

Xin Zhang

Papers

Structural evolution and characteristics of the phase transformations between α-Fe2O3, Fe3O4 and γ-Fe2O3 nanoparticles under reducing and oxidizing atmospheres

Building P-doped MoS2/g-C3N4 layered heterojunction with a dual-internal electric field for efficient photocatalytic sterilization

Synthesis, optical and magnetic properties of α-Fe2O3 nanoparticles with various shapes

L-Cysteine capped Mo2C/Zn0.67Cd0.33S heterojunction with intimate covalent bonds enables efficient and stable H2-Releasing photocatalysis

Z-Scheme Mo2C/MoS2/In2S3 dual-heterojunctions for the photocatalytic reduction of Cr(VI)