A compromise between piezoelectricity and transparency in KNN-based ceramics: The dual functions of Li2O addition

Transparent ceramics with good electrical performance have recently drawn broad interest as promising multifunctional materials. Here, we report that a superior transmittance (T = 75 % at 2000 nm) and good piezoelectricity (d₃₃ ∼ 150 pC/N) can be simultaneously realized in 0.93K_0.5Na_0.5NbO₃-0.07SrZrO₃ (KNN-SZ) ceramics by Li₂O regulation. The effect of Li₂O regulation has two parts: first, the presence of Li₂O facilitates the grain growth of KNN-SZ, considering that it melts at a relatively low temperature as a proper sintering aid; second, the introduced Li⁺ causes local lattice distortion, resulting in the coexistence of orthogonal and tetragonal (O–T) phases. The enlarged grains reduce the light scattering by grain boundaries for a higher optical transmittance; meanwhile, large grains stand as a prerequisite for the macroscopic domain structure favoured for decent piezoelectricity, which could also be partly caused by the coexistence of O–T phases. We believe that these findings might make KNN-based ceramics a preferable candidate for optoelectronic devices.     

Mesoporous yolk-shell structure Bi2MoO6 microspheres with enhanced visible light photocatalytic activity

Mesoporous yolk-shell structure Bi₂MoO₆ (BMO-YS) microspheres were successfully synthesized via a facile solvothermal route in Bi₂MoO₆ precursor solution. The morphology, structure and photocatalytic performance of the BMO-YS in the degradation of Rhodamine B (RhB) were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, nitrogen adsorption–desorption, UV–vis absorption spectroscopy and electrochemical impedance spectra, respectively. The as-prepared BMO-YS mainly consists of microspheres with diameters of about 1.5 μm. The photocatalytic studies reveal that the BMO-YS not only exhibits optimum photocatalytic performance, which may be attributed to the excellent charge separation characteristics and the enhanced light absorption offered by its unique yolk-shell structure, but also possesses excellent recyclability for photocatalysis.     

Tungsten phosphide nanosheets seamlessly grown on tungsten foils toward efficient hydrogen evolution reaction in basic and acidic media

Exploring earth-abundant electrocatalyst with active and stable hydrogen evolution reaction (HER) properties is desirable but still challengeable. Herein, WP₂ nanosheets are seamlessly grown on W foil (WP₂ NSs/W) through phosphorization of WO₃/W. This seamless WP₂/W structure is beneficial to reducing the resistance between WP₂ and W. Along with the exposed large density of active sites, WP₂ NSs/W displays outstanding HER activity with a lower onset potential of about 0 V, a smaller overpotential of 90 mV for the current density of 10 mA/cm² in basic media. Notably, WP₂ NSs/W electrode also catalyzes HER efficiently in acid. The synthesis of WP₂ NSs/W provides us a straightforward strategy to gain more cost-effective cathode for HER.     

TiO2纳米管光电转换特性及应用研究进展

讨论了TiO2纳米管的制备方法、形成机理及其特性的关系,制备方法不同时,其形成机理、结构特点以及其物理化学性能有很大的差异。着重综述了TiO2纳米管的光电特性、影响因素及作为光电极应用于染料敏化太阳电池最新研究进展,并对TiO2纳米管用于光电致变色器件阳极、界面特性等领域的研究及应用进行展望。     

pH条件对肌原纤维蛋白乳液微凝胶性质的影响

肌原纤维蛋白乳液微凝胶是在加热肌原纤维蛋白乳状液过程中同时施加剪切,导致变性蛋白质聚集在乳状液滴上所形成的离散球形颗粒。通过测定不同pH条件下制备的肌原纤维蛋白乳液微凝胶流变行为及微观结构,研究pH对其流变性质的影响。结果表明：在强酸性条件及接近其等电点时,乳液微凝胶的粒径大于其他pH范围。不同pH条件下的乳液微凝胶均为非牛顿流体,具有假塑性流体特征,pH的变化不会改变其流体类型。其黏度随pH的升高呈现先减小后增大的趋势,pH为6时,在低频率扫描时呈现最高的黏弹性,触变性也最好。剪切恢复力测试中,微凝胶颗粒的结构受到一定程度的破坏,其中pH为5时恢复性最好。     

High-temperature glassy-ceramic sealants SiO2—Al2O3—BaO—MgO and SiO2—Al2O3—ZrO2—CaO—Na2O for solid oxide electrochemical devices

Glasses of the SiO₂–Al₂O₃–BaO–MgO and SiO₂–Al₂O₃–ZrO₂–CaO–Na₂O systems were synthesized in the perspective to apply them as sealants in SOFC at operating temperatures of 700–900 °C. Thermal properties of the chosen glass compositions and their compatibility with the SOFC materials (YSZ-electrolyte and alloy-interconnector Crofer22APU, 15×25T) were investigated by means of synchronic thermal analysis and high-temperature dilatometry. The elemental analysis was performed by atomic emission spectroscopy. The average values of the temperature coefficients of the linear extension are 10.0×10⁻⁶ °C⁻¹ for glass 45%SiO₂– 15%Al₂O₃–25%BaO–15%MgO and 9.5×10⁻⁶ °C⁻¹ for glass 60%SiO₂–10%Al₂O₃–10%ZrO₂–5%CaO–15%Na₂O. The gluing microstructure in YSZ/glass/Crofer22APU was studied by scanning electron microscopy. The crystallization process of silicate phases was revealed to occur in the SiO₂–Al₂O₃–BaO–MgO glass. The analysis of the crystallization products was performed by Raman spectroscopy and X-ray diffraction. Glassy ceramics was proved to possess better parameters in comparison with amorphous glass to be used as a sealant in electrochemical sensors and oxygen sensors. The SiO₂–Al₂O₃–ZrO₂–CaO–Na₂O low-temperature amorphous glass can be applied in SOFC.     

Synthesis and properties of cinnamic acid series organic UV ray absorbents–interleaved layered double hydroxides

Organic ultraviolet (UV) ray absorbents, cinnamic acid (CA) and p-methoxycinnamic acid (PMOCA) were intercalated into Zn₂Al layered double hydroxides (Zn₂Al-LDHs) by co-precipitation reaction. The organic–inorganic nanocomposites, Zn₂Al-LDH/CA and Zn₂Al-LDH/PMOCA were obtained. The samples showed excellent UV ray absorption ability and their catalytic activity for the air oxidation of castor oil greatly decreased when the organic UV ray absorbents were intercalated in the layers of the Zn₂Al-LDHs. The studies suggested that Zn₂Al-LDH/organic UV absorbent nanocomposites might be used as safe sunscreen materials.     

Full exploitation of Cannabis sativa as reinforcement/filler of thermoplastic composite materials

Hemp strands and cane straw of hemp have been used as reinforcement and filler of polypropylene composites obtained by injection moulding. The aim of the work was to improve the tensile properties of hemp composites and make them more similar to those obtained with glass fibre composites. For this reason, maleated polypropylene (MAPP) was used as compatibility agent in hemp strand and hemp straw composites. MAPP decreases the hydrophobic nature of PP matrix and enhances the dispersion and the adhesion at interface between both constituents. The hydrophilic property of material’s surface was determined by colloidal titration. The length and diameter of the fibre reinforcement during processing were analysed and their aspect ratio calculated. The tensile results obtained showed that the mechanical properties of hemp strand composites can amount to 80% of the mechanical properties of glass fibre composites.