The production of ultralarge graphene oxide (ULGO) is hindered by sluggish diffusion process of the oxidizing agents into graphite layers, as well as sheet fracture resulting from inhomogeneous oxidation. Previous methods rely on an excess amount of oxidants or multiple oxidation to overcome large diffusion resistance, but at the cost of ULGO yield and environmental risk. Here, we discover the chemical expansion of graphite (CEG) with high solvent-accessible surface areas can effectively boost mass diffusion and facilitate exhaustive oxidation at low oxidant dosage (2 wt equiv). The oxidizing reaction is therefore controlled by the chemical reactivity of graphite with oxidant rather than the diffusion of oxidant, which results in a ∼100% yield of ULGO nanosheets with an area-average size of 128 μm. The worm-like structure of CEG and its oxide provides a chance to recover excess sulfuric acid using a 100-mesh filter, where subsequent exfoliation to ULGO nanosheets is achieved by mild agitation or shaking in several minutes. The ULGO paper prepared by blade casting exhibits superior mechanical properties (Young’s modulus of 11.9 GPa and tensile strength of 110.8 MPa) and electrical conductivity (∼613 S/cm after HI reduction).

Highly sensitive gas sensors are realized from uniformly loaded Pt@SnO2 nanorods, which are synthesized via one-step hydrothermal routes. At 300 °C, the sensitivity of the sensors upon exposure to 200 ppm ethanol is up to 39.5. Such a high gas sensing can be attributed to both the chemical and the electrical contribution of Pt. Interestingly, at 200 °C, the response of the sensors is characterized by opposite variations of resistances, which probably arise from temperature-dependent forms of surface oxygen ions. The present results demonstrate an available direction for realizing high-performance gas sensors.

WO(3) nanorods are uniformly coated with SnO(2) nanoparticles via a facile wet-chemical route. The reversible capacity of SnO(2)/WO(3) core-shell nanorods is 845.9 mA h g(-1), higher than that of bare WO(3) nanorods, SnO(2) nanostructures, and traditional theoretical results. Such behavior can be attributed to a novel mechanism by which nanostructured metallic tungsten makes extra Li(2)O (from SnO(2)) reversibly convert to Li(+). This mechanism is confirmed by x-ray diffraction results. Our results open a way for enhancing the reversible capacity of alloy-type metal oxide anode materials.

Pd-ZnO nanoflowers with high uniformity were prepared via a novel one-step hydrothermal route. High sensitivity, fast response, high selectivity and low work temperature are obtained from Pd-ZnO nanoflower sensors. The sensitivity upon exposure to 300 ppm ethanol is up to 168 at 300  °C and maintains 2.6 at 120  °C. Such behaviors can be attributed to Schottky contact at the Pd/ZnO interface and catalytic activity of Pd nanoparticles. The present results open a way for uniform surface modification of one-dimensional nanostructures with Pd nanoparticles and further enhancing their gas sensing performance.

High heat conduction performance of electrical insulating composite is highly desired in thermal management of electronics. In this study, densely packed boron nitride (BN) composites with resin matrices of epoxy, polymethyl methacrylate, and an acrylic copolymer based binder were prepared through a solvent mediated mixing and compression molding method. The solvent mediated mixing assisted homogeneous dispersion; the compression molding removed excessive resin and led to alignment of BN flakes with high filler content. The resulted composites exhibited superior in‐plane thermal conductivity k// up to 21.3 W/mK and pronounced anisotropic heat conduction properties. The thermal conductivity was positively correlated with density bold-italicρ of a specimen in experimental. A presentation of thermal conductivity bold-italick=bold-italick|bold-italicρ was proposed, and the dependence of thermal conductivity on specimen density bolddbold-italicktrue(bold-italicρtrue)/bolddbold-italicρ > 0 was proven mathematically. The application of BN composite in LED thermal management was demonstrated. An epoxy/BN heat spreader was used to efficiently cool down a 0.3‐W LED. The cooling effect was close to that with Al board heat spreader. POLYM. COMPOS., 39:E1653–E1658, 2018. © 2017 Society of Plastics Engineers

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Pt−ZnO nanoflowers are prepared via a novel one-step hydrothermal route, and Pt nanoparticles are uniformly loaded on the whole surface of the nanoflowers. The growth mechanism of Pt−ZnO nanoflowers is proposed to be a four-stage process. With the help of Raman scattering, photoluminescence, and gas sensing measurements, it has been demonstrated that the optical and sensing properties of Pt−ZnO nanoflowers are greatly enhanced. The surface defects decrease, the concentration of bound excitons under UV illumination increases, and the surface adsorption is enhanced and accelerated. These probably arise from the chemical and electrical effect of Pt. Our results could provoke a promising direction to achieve higher optical and sensing properties of ZnO one-dimensional nanostructures.

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