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Single-walled carbon nanotube (SWCNT)-based flexible thermoelectric films exhibit potential application in wearable electronics due to their good electrical conductivity (σ) and high flexibility. Nevertheless, the low Seebeck coefficient (S) greatly limits their thermoelectric application. The high S of inorganic boron nitride nanosheets is expected to make up for the low S of SWCNT. In this work, exfoliated boron nitride nanosheets (EBNS) are first prepared by solvothermal exfoliation of hexagonal boron nitride (h-BN), which are composited with SWCNT through a simple mixing and filtration method to prepare self-supporting EBNS/SWCNT films with improved thermoelectric properties. Here, the energy filtering effect at the EBNS/SWCNT interface significantly improves the S values of the films. The results show that the maximum S of the EBNS/SWCNT at room temperature is 50.6 μV K–1 and the maximum power factor (PF) is 116.1 μW m–1 K–2 at the EBNS/SWCNT mass ratio of 7.5%. Finally, six pairs of p-type EBNS/SWCNT films and n-type copper sheets are connected in series to assemble a self-powered thermoelectric device, which demonstrates an open-circuit voltage of 8.1 mV and an output power of 550 nW under a temperature difference of 60 K. Therefore, this work provides a simple and effective method to improve the performance of carbon nanotube-based thermoelectric materials. [ABSTRACT FROM AUTHOR]

Carbon nanotubes and their composite thermoelectric (TE) materials have significant advantages in supplying power to flexible electronics due to their high electrical conductivity, excellent flexibility, and facile preparation technology. In this work, stable n-type silver ammonia-polyethyleneimine/single-walled carbon nanotube ([Ag(NH3)2]+-PEI/SWCNT) composite films were facilely prepared by solution blending and vacuum-filtration methods. The results demonstrate that light silver ammonia doping optimizes the carrier concentration and carrier mobility of the composite film, and a maximum power factor (PF) of [Ag(NH3)2]+-PEI/SWCNT of 91.9 μW m−1 K−2 was obtained, which is higher than that of PEI/SWCNT (70.0 μW m−1 K−2). Furthermore, when the composite films were reduced by the NaBH4 solution, the Seebeck coefficient and the PF value were further increased to −45.5 μV K−1 and 115.8 μW m−1 K−2, respectively. For demonstration, a maximum output voltage of 13.8 mV and output power of 492 nW were achieved using a three p–n junction-based TE device constructed by [Ag(NH3)2]+-PEI/SWCNT at a temperature difference of 50 K. Thus, this study provides a metal complex ion doping strategy to improve thermoelectrical properties and air stability of the PEI/SWCNT composite films, which have potential applications in flexible electronics. [ABSTRACT FROM AUTHOR]

Commercial pure titanium（ CP-Ti） TA2 was pressed 1 pass by equal channel angular pressing（ ECAP） with BC route at room temperature（ RT） and 300℃,respectively. The microstructure and mechanical properties of the samples were investigated to find the influence of ECAP temperature on the mechanical properties of CP-Ti. The experimental results suggested that grains of the samples after ECAP 1 pass were elongated and lath-like and crystal twinning was found,the microhardness and tensile strength of the samples pressed 1 pass at room temperature and 300℃ increased from 179. 5 kgf·mm-2,443 MPa to 234. 2 kgf·mm-2,560 MPa and 213. 5 kgf·mm-2、544 MPa,respectively,while the elongation at break reduced from 21. 5% to 11. 5% and 16. 5%,respectively.

To develop high-performance ceramic devices with a low dielectric constant and low dielectric loss, porous ZnAl2O4 ceramics were fabricated by combining a pore-forming agent and partial sintering using ZnAl2O4 particles with an average size of 80 nm as the precursor and polyethylene glycol (PEG) as the pore-forming agent. The microstructure and dielectric properties of the porous ZnAl2O4 ceramics were investigated. As the PEG content increased from 10 to 24 wt%, the porosity of the ceramics increased from 53.80 to 63.30%, the thermal conductivity decreased from 0.446 to 0.212 W/m K, the compressive strength decreased from 15.74 to 11.75 MPa, and the dielectric constant decreased from 5.63 to 3.74, respectively. The increase in porosity with increasing pore-forming agent contributed to the low dielectric constant and low thermal conductivity while maintaining good mechanical properties. Moreover, the uniform pore structure of the ceramics supported the low dielectric loss. The prepared porous ZnAl2O4 ceramics can be used as a new type of wave-transmitting material. [ABSTRACT FROM AUTHOR]

ABSTRACT 1,3-Dimethyl-2-imidazolidinone (DMI) was used as an efficient media in iron-catalyzed atom transfer radical polymerizations (ATRPs) and AGET ATRPs of MMA. Both of these systems presented relatively high reaction rate and well controllability even in the presence of limited amount of DMI. In iron-catalyzed AGET ATRPs, a variety of alcohols were served as reducing agents and all the polymerizations behaved excellent activity features, especially for glycerol. The hydrogen-bond interaction between DMI and glycerol was also studied, which may release the reducing ability of glycerol by decreasing the viscosity of glycerol similar to deep eutectic solvents (DESs). © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 282-289 [ABSTRACT FROM AUTHOR]

A way to prepare nano-size Cu2O with electrochemical method was first reported. The nano-size TiO2–Cu2O particle composites were obtained by an electrochemical method and the properties of the composites were evaluated by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance UV–Vis spectroscopy (UV-DRS). The photocatalytic activities of the composites prepared by this method exceed that of Degussa P-25. [Copyright &y& Elsevier]

Single-walled carbon nanotube (SWCNT)-based thermoelectric materials have been extensively studied in the field of flexible wearable devices due to their high flexibility and excellent electrical conductivity (σ). However, poor Seebeck coefficient ( S ) and high thermal conductivity limit their thermoelectric application. In this work, free-standing MoS 2 /SWCNT composite films with improved thermoelectric performance were fabricated by doping SWCNTs with MoS 2 nanosheets. The results demonstrated that the energy filtering effect at the MoS 2 /SWCNT interface increased the S of composites. In addition, the σ of composites was also improved due to the reason that S -π interaction between MoS 2 and SWCNTs made good contact between MoS 2 and SWCNTs and improved carrier transport. Finally, the obtained MoS 2 /SWCNT showed a maximum power factor of 131.9 ± 4.5 μW m -1 K -2 at room temperature with a σ of 680 ± 6.7 S cm -1 and an S of 44.0 ± 1.7 μV K -1 at a MoS 2 /SWCNT mass ratio of 15:100. As a demonstration, a thermoelectric device composed of three pairs of p-n junctions was prepared, which exhibited a maximum output power of 0.43 μW at a temperature gradient of 50 K. Therefore, this work offers a simple method of enhancing the thermoelectric properties of SWCNT-based materials.