Built-in piezoelectric field improved photocatalytic performance of nanoflower-like Bi2WO6 using low-power white LEDs

Photocatalysis technology has been proved to be a potential strategy for removal of organic dyes, however high-power light sources are generally necessary to initiate photocatalytic reaction. In this work, we employed an excellent photocatalyst of Bi₂WO₆ with visible light harvest and meanwhile an intrinsic ferroelectricity, which realized the efficient degradation of organic dye via the synergetic photopiezocatalysis. Through coupling the illumination by a low-power (9 W) LED and the ultrasonic vibration (120 W) by an ultrasonic cleaner, the nanoflower-like Bi₂WO₆ composed of ultrathin nanosheets showed a much more enhanced photopiezocatalysis performance for purification of organic dye than the individual photocatalysis and piezocatalysis. Furthermore, the high mineralization efficiency and the good durability of the Bi₂WO₆ catalyst were demonstrated. The possible mechanism of photopiezocatalysis was finally proposed, where the ultrasound-induced piezoelectric field in Bi₂WO₆ drove photo-generated electrons and holes to diffuse along opposite directions, consequently promoting the separation efficiency of charge carriers. This work indicates that the synergetic photopiezocatalysis by coupling irradiation and ultrasonic vibration is a promising strategy to purify organic pollutants in wastewater.     

Improved optical single-sideband generation using the self-modulation birefringence difference in semiconductor optical amplifiers

By employing the self-modulation birefringence difference in a semiconductor optical amplifier (SOA), an improved method is proposed to generate a complete optical single-sideband (OSSB) signal. Over 30 dB sideband suppression ratios (SSRs) of lower OSSB signals are obtained over a 12 dB input power range and a 36 nm wavelength span, with a maximum of over 35 dB. Upper OSSB signals with an SSR of over 15 dB are observed using a SOA for what is believed to be the first time. This method is effective even for the carrier-suppressed signal. The theory for OSSB generation in an SOA is extended and verified by experiment.     

Improvement of resistive switching fluctuations by using one step lift‐off process

Bipolar resistive switching characteristics are investigated in ZrO₂ containing Cu thin layer devices, particularly for the self‐isolated‐structure device fabricated by one step lift‐off process. Compared with the traditional‐structure device, the self‐isolated‐structure device shows more uniform resistive switching characteristics. This is because the isolation of each device cell has negligible influence on each other and thus mitigates possible crosstalk between each cell. These results suggest that the feasibility of good stabilization of the resistive switching parameters can be obtained through one step lift‐off process. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

静电纺丝制备YVO4:Sm3+纳米纤维及其荧光光谱性能

采用静电纺丝技术与高温煅烧工艺相结合,以氧化钐、氧化钇、偏钒酸铵和聚丙烯腈为主要原料,制备稀土离子掺杂的YVO4:Sm3+纳米纤维。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、傅立叶变换红外(FT-IR)、热重-差热(TG-DTA)和荧光光谱(PL)等分析测试手段对所得样品的结构、形貌和荧光光谱性能进行表征。研究结果表明:静电纺丝制备的有机-无机复合纤维的直径在200~250 nm之间,经过900℃热处理后,所得YVO4:Sm3+样品纤维状结构保持完好,直径减至100 nm。掺杂的稀土Sm3+离子在YVO4纤维中显示出特征发射,同时VO3-4和稀土Sm3+离子之间存在能量传递;Sm3+的掺杂浓度为2%(摩尔分数)时发光强度最大。     

Intrinsic Peroxidase‐like Activity of Porous CuO Micro‐/nanostructures with Clean Surface

Porous CuO micro‐/nanostructures with clean surface, prepared through Cu₂(OH)₂CO₃ precursor followed by calcination in air, were proven to be an effective peroxidase mimic. They can quickly catalyze oxidation of the peroxidase substrate 3,3′,5,5′‐tetramethylbenzidine (TMB) in the presence of H₂O₂, producing a blue color. The obtained porous CuO micro‐/nanostructure have potential application in wastewater treatment. The apparent steady‐state kinetic parameter was studied with TMB as the substrate. In addition, the potential application of the porous CuO in wastewater treatment was demonstrated with phenol‐containing water as an example. Such investigation not only confirms the intrinsic peroxidase‐like activity of micro‐/nanostructured CuO, but also suggests its potential application in wastewater treatment.     

Preparation and characterization of Ti0.7Sn0.3O2 as catalyst support for oxygen reduction reaction

Sn-doped TiO_2 nanoparticles with high surface area of 125.7 m~2·g~(-1) are synthesized via a simple one-step hydrothermai method and explored as the cathode catalyst support for proton exchange membrane fuel cells.The synthesized support materials are studied by X-ray diffraction analysis,energy dispersive X-ray spectroscopy and transmission electron microscopy.It is found that the conductivity has been greatly improved by the addition of 30 mol%Sn and Pt nanoparticles are well dispersed on Ti_(0.7)Sn_(0.3)O_2 support with an average size of 2.44 run.Electrochemical studies show that the Ti_(0.7)Sn_(0.3)O_2 nanoparticles have excellent electrochemical stability under a high potential compared to Vulcan XC-72.The as-synthesized Pt/Ti_(0.7)Sn_(0.3)O_2 exhibits high and stable electrocatalytic activity for the oxygen reduction reaction.The Pt/Ti_(0.7)Sn_(0.3)O_2 catalyst reserves most of its electrochemically active surface area(ECA),and its half wave potential difference is 11 mV,which is lower than that of Pt/XC-72(36 mV) under 10 h potential hold at 1.4 V vs.NHE.In addition,the ECA degradation of Pt/Ti_(0.7)Sn_(0.3)O_2is 1.9 times lower than commercial Pt/XC-72 under 500 potential cycles between 0.6 V and 1.2 V vs.NHE.Therefore,the as synthesized Pt/Ti_(0.7)Sn_(0.3)O_2 can be considered as a promising alternative cathode,catalyst for proton exchange membrane fuel cells.     

分子氧为氧化剂磷钒酸盐为催化剂超深度氧化脱除柴油中的二苯并噻吩

一种“双帽Keggin型”磷钒酸盐在温和的反应条件下以分子氧为氧化剂氧化二苯并噻吩至二苯并噻吩砜的反应中表现出很高的催化活性. 用溶剂萃取或者选择吸附等方法可轻易地将反应产生的二苯并噻吩砜从油品中除去. 这提供了一种新型的分子氧为氧化剂的超深度氧化脱硫方法.     

Electroactive shape memory effect of radiation cross-linked SBS/LLDPE composites filled with carbon black

The poly(styrene-b-butadiene-b-styrene) (SBS) triblock copolymer and linear low-density polyethylene (LLDPE) were blended and irradiated by γ rays to prepare shape memory polymer (SMP). Different weight fractions of conductive carbon black (CB) were filled into SMP to form a novel electroactive shape memory CB/SBS/LLDPE composite. The CB reinforced radiation cross-linked SBS/LLDPE blends for the improvement of the mechanical weakness and conductivity of SBS/LLDPE bulk and for wide practical engineering uses. The electroactive shape memory CB/SBS/LLDPE composites were investigated by electrical properties, mechanical, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and electroactive shape memory effects. It is found that the tensile strength, storage modulus, and resistance against mechanical and thermal mechanical cycle loading in the developed composites increased due to the role of reinforcement of CB. The melting temperatures and volume resistance of the composites decreased with the increment of CB for excellent electrical conductivity of CB. The electroactive shape memory effects of developed CB/SBS/LLDPE composites were affected by CB weight fractions and applied voltage, while good shape recovery could be obtained in the shape recovery test. When the CB fraction is more than 5 wt%, full recovery can be observed after tens of seconds and shape recovery speed increased with CB fractions and voltage increasing. However, the shape recovery rate decreases slightly with increment of cycle times.     

α-Al_2O_3比表面积标准物质的研制

选择市售α-Al2O3粉体作为比表面积标准物质候选材料,采用交叉缩分方法对标准物质样品进行分装。检验结果表明α-Al2O3标准物质样品具有良好的均匀性和稳定性(18个月)。采用国际公认的氮气物理吸附BET方法,联合测量能力经过确认的8家实验室对α-Al2O3标准物质样品进行定值,标准值比表面积为5.47 m2/g,不确定度为0.22 m2/g(k=2)。     

浅谈制药工程专业有机化学实验教学的心得和体会——以三苯甲醇的制备和重结晶实验为例

有机化学实验是制药工程专业的一门必修课,旨在训练学生有机合成基本实验技能。本文以三苯甲醇的制备和重结晶实验为例,讲述了笔者在多年教学中获得的一点感悟和经验:1)将实验步骤分解成片断讲解可以使学生更好地理解和记忆实验过程和操作目的;2)重要的基本操作应反复练习,即"学习、复习、提高",通过三次重复练习来实现巩固和熟练掌握该操作的目的。