Palladized dysprosium fluoride nanorods as a new performance catalyst in direct methanol fuel cell

Fuel cells are a new type of batteries that produce electricity from a continuous source of alcohols as long as fuel is inserted. In this study, decorated palladium nanoparticles (PdNPs) on dysprosium fluoride (DyF₃) nanorods (DyFNRs)‐multiwalled carbon nanotubes (MWCNTs) were used for electrooxidation of methanol. DyFNRs were synthesized by the hydrothermal method, and the proposed multifunctional catalyst (DyFNRs/MWCNT‐PdNPs) was identified by several methods such as X‐ray diffraction, elemental mapping images, field emission scanning electron microscopy, energy dispersive analysis of X‐rays, and transmission electron microscopy which demonstrated a uniform distribution and high dispersion of the PdNPs on the supports. The electrocatalytic activity toward methanol electrooxidation on glassy carbon electrode (GCE) with DyFNRs/MWCNT‐PdNPs (DyFNRs/MWCNT‐PdNPs/GCE) was investigated by cyclic voltammetry (CV) and chronoamperometry (CA). Experimental results showed a high improvement in oxidation potential and peak current of methanol electrooxidation by DyFNRs/MWCNT‐PdNPs in comparison to DyFNRs and PdNPs. The values of the catalytic rate constant (k) and physical dimension (D_s) for methanol oxidation on the DyFNRs/MWCNT‐PdNPs/GCE catalyst were calculated 0.008 s^?1 and 1.43, respectively. Moreover, the order of reaction was determined to be 0.43 and 0.13 for CH₃OH and NaOH, repectively. Finally, the synthesized catalyst was evaluated in direct methanol fuel cell (DMFC). The single DMFC with proposed anodic catalyst, DyFNRs/MWCNT‐PdNPs, indicated a power density of 4.4 mW·cm^?2 at a current density of 18 mA·cm^?2 in alcohol (1 M) and NaOH (1 M).     

Tunable BaxSr1-xTiO3 nanoparticles induced high energy storage density in layer-structured asymmetric polymer-based nanocomposites

In order to solve the problem of low charging and discharging energy density of dielectric capacitors, the structure design of layered polymer matrix composites is carried out in this paper. Ba_0.7Sr_0.3TiO₃, Ba_0.8Sr_0.2TiO₃ and Ba_0.9Sr_0.1TiO₃ nanoparticles were successfully prepared by the oxalate coprecipitation method. The surface of Ba_xSr_1-xTiO₃ was successfully coated with dopamine, which promoted the dispersion of the polymer matrix of the ceramic powder. Monolayer Ba_xSr_1-xTiO₃/PVDF composites containing Ba_xSr_1-xTiO₃ with different Ba/Sr ratios were successfully prepared by the casting method. Three-layer asymmetric composites with different fillers were successfully prepared by layer-by-layer casting. The phase and microstructure of the as-prepared materials were analyzed by XRD and SEM. The dielectric, electrical conductivity, ferroelectric and energy storage properties of the composites were tested. The effects and laws of the design of the three-layer asymmetric structure on the dielectric properties and energy storage properties of the layered composites are mainly studied. When the structure of the three-layer asymmetric composite is 1-2-3, the breakdown field strength reaches 330 kV/mm, the discharge energy density reaches 8.51 J/cm³, and the charge-discharge efficiency is 67%. This work demonstrates that layered composites with asymmetric properties can facilitate the development of electrical energy storage.     

Novel polymer composites of RuO2@nBaTiO3/PVDF with a high dielectric constant

The dielectric properties of a novel polymer dielectric material were investigated. The conductive phase of RuO₂ was synthesized for deposition on the surface of a nanosized BaTiO₃ (nBT). The RuO₂@nBT hybrid particles were incorporated into a poly (vinylidene fluoride) (PVDF) as a three-phase composite (RuO₂@nBT/PVDF). The obtained dielectric constant (ε′) was significantly high (3837.16) for the composite with a volume fraction of $f_{Ru{O}_2@nBT}$ = 0.50. The large interfacial polarization between the RuO₂?nBT and RuO₂?PVDF interfaces considerably increased the value of ε′. Therefore, interfacial polarization is a critical factor in improving the dielectric properties. The dielectric behavior of the RuO₂@nBT/PVDF composites can be described using the effective medium percolation theory model, which indicates the significant contributions of the conductive RuO₂ phase and high-permittivity nBT phase.     

Ф3．5m氟化氢反应炉的研制

采用设计院技术对无水氟化氢反应炉进行研制，克服筒体整体加工、动静密封配研、夹套的焊接、传动部分加工等难题，并针对研制过程中的关键技术难题，采取合理工艺措施，满足了反应炉的制造要求，为类似产品的制造提供借鉴。     

氟化铵对纳米金红石型钛硅复合氧化物表面改性研究

以硫酸氧钛为钛源、硅酸钠为硅源,采用改进的水解沉淀法制备了纳米金红石型钛硅复合氧化物(TiO_2-SiO_2),以氟化铵(NH_4F)为表面改性剂,采用水热法在不同溶剂中对TiO_2-SiO_2进行改性,并通过X-射线衍射仪、傅里叶红外光谱仪、扫描电镜、原子力显微镜和接触角测量仪等,研究了不同溶剂对改性效果的影响。结果表明,以异丙醇为溶剂进行NH_4F改性时,由于表面Si-F键的形成、异丙醇表面自组装和表面微纳分层粗糙结构的形成等因素的协同作用,改性后的纳米金红石型TiO_2-SiO_2比表面积大,具有良好的表面性能,其比表面积达332 m2/g,水和二碘甲烷接触角分别达到147.1°和147.2°。     

A Wearable Respiration and Pulse Monitoring System Based on PVDF Piezoelectric Film

A novel wearable sensor system was developed for monitoring respiration and pulse using polyvinylidene fluoride (PVDF) piezoelectric films as sensor materials. Due to the different signal intensity between respiration and pulse, a “double-sided arch” structure and a “thin-shell” structure were designed and fabricated as substrates for the respiratory sensor and pulse sensor, respectively. These sensors installed on belts can be easily tied on the chest, abdomen, or wrist for comfortable fit. In order to obtain clear respiratory and pulse signals from the sensor patch, some high-quality signal processing modules were designed. The digital signals were transmitted to a computer via Bluetooth and displayed by LabVIEW software. The fundamental principle and functional verification of the developed sensor system were described in this study. By comparing the sensor signals from the proposed structure with those of flat structure, it can be concluded that the proposed sensor is more sensitive and stable than its flat counterpart. In addition, the whole sensor system has the features of ease of use and comfortable to wear. All these make the proposed sensor system a promising sensing device for respiration and pulse real time monitoring.     

半导体制造用高纯电子气体新品种的现状

对我国半导体生产过程中几种主要特种气体的现状进行了回顾,指出了我国超纯电子气体国产化过程中存在的问题。     

PVDF/SiO_2复合纤维膜的制备及电化学性能

采用静电纺丝法制备了SiO2含量分别为2%、5%和8%的PVDF/SiO2复合纤维膜,对复合纤维膜的物理性能、电化学性能以及组装电池性能等进行了测试分析。结果表明:纳米SiO2含量对静电纺PVDF基膜的纤维直径和形貌影响很大,随着SiO2含量的增加,静电纺PVDF/SiO2复合纤维膜的纤维直径变细且分布变宽,纤维表面的均匀性降低;其力学性能、电解液吸液率以及离子电导率均先增加后降低。以含量为5%的SiO2静电纺PVDF/SiO2复合纤维膜为隔膜组装的电池首周充放电容量最高,约为158 m Ah/g;经过50周充放电循环后,电池的容量保持率最高为91%。     

聚酯纤维机织物-聚氯乙烯-聚偏氟乙烯膜材双轴剪切力学性能试验

为研究聚酯纤维机织物-聚氯乙烯-聚偏氟乙烯(P-PVC-PVDF)膜材的双轴剪切力学性能,提出了工程剪应变计算方法、改进的剪应力计算方法和应力加载方法。基于自主研制的双轴拉伸试验机,对P-PVC-PVDF膜材进行了双轴剪切力学性能试验,得到了膜材剪应力-剪应变曲线、剪切模量和滞回环面积。分析结果表明,剪应力由正变为负后,各力学参数有所差异,但均在加载一次后趋于稳定。当剪应力的上下限设定为±2kN/m时,稳定后的剪切模量范围为11~13kN/m。通过对比证明,主轴与加载方向的夹角变化对计算结果影响不大。研究成果对膜结构设计与分析具有参考价值。