Evaluating hydrogen detection performance of an electrospun CuZnFe2O4 nanofiber sensor

CuZnFe₂O₄ nanoparticles (<50 nm) are successfully synthesized and incorporated in polyvinyl alcohol (PVA) to fabricate nanofibers via electrospinning technique followed by calcination process under various temperatures. Scanning electron microscopy (SEM) is used to observe the morphological characteristics of both nanoparticles and nanofibers. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermo-gravimetric (TG) analyses along with energy dispersive X-ray spectrometer (EDX) analysis are conducted to evaluate structure and composition of the nanofibers, respectively. The results exhibit that the calcination temperature is substantially effective on nanofiber morphology and sensing performance in the context of forming grains (beads) on the nanofibers. The highest response and recovery performance values (response and recovery time of about 6.5 s) are obtained at the calcination temperature of 500 °C and sensor working temperature of 250 °C at 500 ppm of H2 gas concentration which also corresponds to 30% increment in detection performance compared to 300 °C-calcined nanofiber sensor. The sensor selectivity against various gases is also analyzed to compare the detection performance in air.     

Graphitized carbon nanocages/palladium nanoparticles: Sustainable preparation and electrocatalytic performances towards ethanol oxidation reaction

Graphitized carbon (GC) nanocages have been successfully prepared via a sustainable carbon powder buried-type Ni catalysis-growth technology from Tween-80 molecule precursor. The GC nanocages are used as support for the further construction of GC/Pd electrocatalyst towards ethanol oxidation reaction. The material structures and surface morphologies are studied by XRD, SEM and TEM techniques. The electrochemical properties are investigated by CV, LSV, EIS and CP techniques. The results showed that GC nanocages have good graphited structure and plentiful opening gaps, and the Pd nanoparticles were evenly distributed on the inner and outer surfaces of GC nanocages. The GC/Pd electrocatalyst exhibits excellent electrocatalytic performance towards ethanol oxidation. The positive scanning peak current density of GC/Pd electrode is up to 1612 A/g Pd in 1.0 mol/L NaOH +1.0 mol/L ethanol electrolyte, which is much higher than those (500–1100 A/g Pd) of traditional Pd electrodes supported with carbon nanotubes or graphene nanosheets.     

甲烷与冰快速形成天然气水合物的影响因素研究

设计了冰-气生成天然气水合物的实验装置,对由冰和甲烷反应生成天然气水合物的影响因素进行实验研究。结果表明,压力越高,温度越低,冰粒越小,越有利于水合物的生成,促进水合物快速形成的搅拌速度和促进剂浓度最佳值分别是800 r/min和800 mg/L。     

Extending donor size in D-A-π-A organic dye for dye sensitized solar cells: Anti-aggregation and improving electron injection

We have theoretically designed two D-A-π-A dyes 3 and 4 based on the efficient references 1 and 2 by introducing an extra electron donor unit (D2). Via calculating the electronic structures of isolated dyes, we obtain that dyes 3 and 4 possess stronger light-harvesting efficiency imparted by the fluorescence energy transfer of D2 part, maintain comparable lifetime of excited states, and shorten the electron injection time significantly with regard to 1 and 2. Meanwhile, dye 3 positively shifts the edge of virtual states of TiO₂ in a larger extent compared to its counterparts. Then after considering the alignment morphology of multiple dyes adsorbed on TiO₂ surface, we find that dyes 3 and 4 manifest the capability of anti-aggregation obviously, which is evidenced by the smaller quantity of intermolecular electronic coupling compared to that of dyes 1 and 2, definitively illustrating the prominent performance of novel dyes with the bulky D2 moiety. Finally, dye 3 is screened out as the potential candidate for future application.     

油气储运工程专业实验教学体系的构建

分析了油气储运工程专业实验教学体系构建的必要性。研究了当前油气储运工程专业实验教学体系存在的问题,从培养应用型人才的目标出发,构建了油气储运工程专业实验教学新体系。新的体系由基础性通用实验、专业基础实验、专业实验、综合性设计型实验四个层次组成,四个层次是依次递进的关系,每个层次都以培养学生的能力为指导思想进行教学。     

曝气生物滤池技术的研究进展

综述了曝气生物滤池污水处理技术在填料、运行工艺、微生物相等方面的最新研究进展,展望了曝气生物滤池今后的研究方向。     

Photoluminescent and electrical properties of novel Nd3+ doped ZnV2O6 and Zn2V2O7

Nd³⁺ doped ZnV₂O₆ and Zn₂V₂O₇ samples were synthetized by using melt-quenching method. X-ray diffraction patterns indicate that both samples are polycrystalline. The crystallinity was also verified by Raman scattering, from which the different vibrational modes of ZnV₂O₆ and Zn₂V₂O₇ were detected. Electron dispersive spectroscopy (EDS) analysis shows that the Nd³⁺ incorporation into the ZnV₂O₆ and Zn₂V₂O₇ hosts is around 0.9±0.1 and 0.2±0.1 at%, respectively. The micrographs obtained by Scanning Electron Microscopy, reveal that the Nd³⁺ doped ZnV₂O₆ sample is predominantly composed by micro-rods, whereas the Nd³⁺ doped Zn₂V₂O₇ one is only composed by irregular blocks. The band gap energies (E_g) were calculated from the diffuse reflectance spectra by the Kubelka–Munk equation; E_g values resulted to be 2.24 and 2.86 eV for the Nd³⁺ doped ZnV₂O₆ and Zn₂V₂O₇ samples, respectively. By means of two points dark conductivity measurements, conductivity values in the 10⁻⁴–10⁻⁶ and 10⁻⁶–10⁻⁸(Ω cm)⁻¹range for the Nd³⁺ doped ZnV₂O₆ and Zn₂V₂O₇ samples were measured, respectively. The conductivity as a function of the temperature indicated a semiconductor behavior. The photoluminescence spectra upon Ar⁺ laser excitation at 488 nm, exhibited the Nd³⁺ characteristics emissions. For instance, the Nd³⁺ doped ZnV₂O₆ sample displayed the Nd^{3+ 4}F_5/2→⁴I_9/2 and ⁴F_3/2→⁴I_9/2 emissions; while the Nd³⁺ doped Zn₂V₂O₇ one showed the Nd³⁺ characteristic emissions associated with the ⁴G_7/2, ⁴F_9/2, ⁴F_5/2 and ⁴F_3/2→⁴I_9/2 transitions. The lifetimes were 80 and 130 µs for the Nd³⁺ doped ZnV₂O₆ and Zn₂V₂O₇ samples, respectively. All these results suggest a successful synthesis of Nd³⁺ doped zinc vanadate compounds by the melt-quenching technique.     

Photocatalytic evolution of hydrogen over mesoporous TiO2 supported NiO photocatalyst prepared by single-step sol–gel process with surfactant template

Photocatalytic activity of mesoporous titania supported nickel oxide photocatalyst synthesized by single-step sol–gel (SSSG) process combined with surfactant-assisted template method was investigated for hydrogen evolution from an aqueous methanol solution, in comparison with one prepared by conventional incipient wetness impregnation (IWI) method. In single-step sol–gel process, nickel precursor was introduced into the titania sol prepared with the aid of a surfactant template behaving as pore-controlling agent to attain meso-scaled pore. The single-step sol–gel photocatalyst was experimentally found to enhance the photocatalytic evolution of hydrogen rather than the impregnated one. The optimum level of nickel loading in photocatalytic activity test for single-step sol–gel method was slightly higher than that for incipient wetness impregnation method. Characterization results demonstrated the significant modification of physical characteristics of the single-step sol–gel photocatalyst, anticipated to relating to the observation of higher photocatalytic hydrogen evolution activity.     

Conducting radical salts of the new electron donor bis(1.3-cyclobutylenedithio)tetrathiafulvalene

The new π-electron donor bis(1.3-cylobutylenedithio)tetrathiafulvalene (1.3-CBDT-TTF), which is only slightly different in the periphery of the molecule with respect to the well-known donor BEDT-TTF, was synthesized. The molecular structure has been characterized and the electrochemical behavior of this new donor was investigated. New cation radical salts were prepared by electrocrystallization methods. The structures of (1.3-CBDT-TTF)I₂, (1.3-CBDT-TTF)₂[AuI₂], (1.3-CBDT-TTF)_x(ReO₄)_y and (1.3-CBDT-TTF)₂PF₆·THF were characterized by X-ray analyses. The room temperature electrical resistivities of the radical salts are low and range between 0.5 and 5 Ω cm.     

铝合金等离子体氧化放电特性及陶瓷膜层耐腐蚀性能研究

采用等离子体电解氧化技术在AA6063铝合金表面制备陶瓷膜层,拟提高铝合金耐腐蚀性能。对等离子体氧化过程电流电压特性及击穿放电特性进行了分析和探讨,采用光发射光谱仪对等离子体氧化放电阶段等离子体活性组分进行分析,对陶瓷膜层的耐腐蚀性能进行了研究。结果表明,相比于基体而言,等离子体氧化陶瓷膜层腐蚀电位正移了0.86V。在470V时,等离子体活性物种主要由Al、Al+、Mg、O+、Hα、Hβ、OH、Na和K组成,且金属活性物种先被激发。这些活性物种中金属元素及工作电极表面产生的气体的原子和分子对等离子体场能量的稳定起到关键的作用。