查看更多>>摘要：The development of novel lead-free materials operating at high temperature and able to replace lead-based compounds and their derivatives in different devices is currently a remarkable challenge. In spite of having a high Curie temperature, the ferroelectric Bi_4Ti_3O_(12) is rarely used as a piezoelectric due to its high conductivity. In this work, Bi ions in Bi_4Ti_3O_(12) were partially replaced with Yb and Er aiming to compensate oxygen vacancies and improve others physical properties. In particular, Bi_(3.8-x)Er_(0.2)Yb_xTi_3O_(12) compounds with x = 0.05, 0.1, and 0.2 were prepared by a low-cost solid-solid state reaction process, and their structural, optical and electrical properties were investigated. It was observed that, at low temperatures, the conductivity, impedance and permittivity are mainly governed by grain effects, and by grain boundaries and grains effects at high temperatures. The electrical conductivity at 700 K decreases with Yb content and shows a minimum for x = 0.2. The relative permittivity at high temperatures is colossal while the tangent loss is negligible. High permittivities accompanied with low loss factor were obtained for Bi_(3.6) Er_(0.2)Yb_(0.2)Ti_3O_(12). These results open a wide application domain for this particular compound.
查看更多>>摘要：The authors regret that the layer thickness and hatch spacing in Table 2 should be 0.05 and 0.12 mm respectively in the original paper. Meanwhile, an incorrect version of Fig. 7 was used. The correct version is exhibited below.
查看更多>>摘要：Metal oxide supports have attracted much attention for improving the performance and durability of polymer electrolyte fuel cells. In this study, niobium-doped tin oxide (NTO) nanoparticles with a network structure were synthesized and Pt catalysts deposited on them using a flame aerosol technology. Because the flame method involves a variety of particle formation processes, which depend on the type of raw material and combustion method used, the effect of these processes on the particle structure, of the flame-made Pt/NTO was evaluated. When Pt/NTO nanoparticles were prepared by flame-assisted spray pyrolysis (FASP) using an inorganic raw material (metal chloride) with lower combustion enthalpy, the precursor liquid burned incompletely and Pt aggregation was observed. However, when flame spray pyrolysis (FSP) using a combustible precursor solution was used, the precursor rapidly evaporated in spray flames, and NTO with uniformly dispersed Pt was synthesized through gas-to-particle conversion. The electrochemical surface area and mass activity values of 5.44 wt% Pt-loaded NTO particles prepared by FSP were 48.2 m~2 g~(-1) Pt and 338 mA mg~(-1) Pt, respectively. Flame aerosol synthesis of supported metal catalysts can be widely used as a dry one-step process that does not involve any complicated post-treatment. The two types of noble metal loading processes revealed in this study provide important insights for determining particle design guidelines for in-situ production of supported metal catalysts in flames.
查看更多>>摘要：White light-emitting diodes (LEDs) are great candidates for general lighting. Phosphors have commonly been used for the color conversion layers of white LEDs; however, they backscatter more than half of the down-converted light, which is lost within the device, thus degrading the overall performance. In this study, we propose and demonstrate white LEDs with improved efficiency enabled by the intimate integration of Ag@SiO_2-supported blue InGaN/GaN nanorod LEDs together with green- and red-emitting perovskite nanocrystal (PNC) films as color conversion layers. The photoluminescence (PL) intensity of the blue LEDs (BLEDs) was significantly enhanced owing to the localized surface plasmon (LSP) effect of Ag@SiO_2 nano-particles. In addition, the perovskite PL intensity was improved by the high-power BLED backlight. The resulting PL intensity of the Ag@SiO_2 nanoparticle-embedded nanorod white LED was 62% greater than that of a planar white LED.
查看更多>>摘要：The removal of low concentration pollutants in water is very important for environmental remediation. Herein, MCr-LDHs/BiOBr (M = Zn, Ni, Cu) heterojunction nanocomposites were fabricated by a facile rapid crystallization method. Visible-light responsive heterojunctions could be formed efficiently at the intimately contacted interface between BiOBr nano-crystallites and LDHs nano-flakes, which showed higher photocatalytic degradation activities of cationic, anionic, and electrically neutral organic pollutants than pristine LDHs and BiOBr. Degradation of 99.5% Rhodamine B, 80% methyl orange, and 97% bisphenol A could be achieved by the composite catalysts under visible-light irradiation in 15 min, 60 min, and 40 min, respectively, and cycling test proved the good reusability of composite catalysts as well. Benefitting from superior adsorption properties for ionic organic pollutants, and effective separation and transition of photogenerated holes and electrons, the MCr-LDH/BiOBr composite catalysts exhibit wide applicability for removal of various organic pollutants in water and have potential application prospects in the future.
查看更多>>摘要：Exploring comwposite nanomaterials with novel and stable nanostructures is of great importance for high performance supercapacitors (SCs). Herein, the nanosheet-like XMoO_4 (X=Ni, Co) were uniformly grown on the carbon submicrofibers (CMFs) by a facile hydrothermal route. The NiMoO_4 @CMFs exhibits higher specific capacitance of 1485.53 F g~(-1) and better cycling stability with 87.6% retention after 3000 cycles at 1 A g~(-1) than that of CoMoO_4 @CMFs (1407.1 F g~(-1) 80.6% retention after 3000 cycles at 1 A g~(-1)). To further improve the electrochemical performance of NiMoO_4 @CMFs, the hollow porous carbon submicrofibers (HPCMFs) were designed and used as a substrate for NiMoO_4. Benefiting from the hollow porous structure, the HPCMFs can provide large specific surface area for electrolyte permeating and supply more ion channels in the charge-discharge process. Therefore, the NiMoO_4 HPCMFs exhibits a high specific capacitance of 1600.0 F g~(-1) at 1 A g~(-1) and good cycling stability of 90.7% retention after 3000 cycles. The all-solid stated symmetric supercapacitors (ASSCs) were directly assembled by using NiMoO_4 @HPCMFs as electrode without any additives, which shows good flexibility and a high energy density of 55.33 Wh kg~(-1) at a power density of 999.89 W kg~(-1). Moreover, five series ASSCs can light 'DHU' logo, indicating potential application prospect in wearable electronics.
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Elsevier