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71.
Polymer nanodielectrics render a great material platform for exhibiting the intrinsic nature of incorporated particles, particularly semiconducting types, and their interfaces with the polymer matrix. Incorporating the oxide fillers with higher loading percentages (>40 vol%) encounters particular challenges in terms of dispersion, homogeneous distribution, and porosity from the process. This work investigated the dielectric loss and electrical conduction behaviors of composites containing semiconducting ZnO varistor particles of various concentrations using the epoxy impregnation method. The ZnO varistor particles increased the dielectric permittivity, loss, and electrical conductivity of the epoxy composites into three different regimes (0–50 vol%, 50–70 vol%, 70–100 vol%), particularly under an electric bias field or at higher temperatures. For lower loading fractions below 50 vol%, the dielectric responses are dominated by the insulating epoxy matrix. When loading fractions are between 50 and 70 vol%, the dielectric and electric responses are mostly associated with the semiconducting interfaces of ZnO varistor particles and ZnO–epoxy. At above 70 vol%, the apparent increase in the dielectric loss and conductivity is primarily associated with the conducting ZnO core forming the interconnected channels of electric conduction. The foam-agent-assisted ZnO varistor particle framework appears to be a better way of fabricating composites of filler loading above 80 vol%. A physical model using an equivalent capacitor, diode, and resistor in the epoxy composites was proposed to explain the different property behaviors. 相似文献
72.
Andris utka Linda Meule Viktorija Denisova Jochen Meier-Haack Akshay Kulkarni Sanda Bitina Krisjanis Smits Svetlana Vihodceva 《Molecules (Basel, Switzerland)》2022,27(22)
Flexible antibacterial materials have gained utmost importance in protection from the distribution of bacteria and viruses due to the exceptional variety of applications. Herein, we demonstrate a readily scalable and rapid single-step approach for producing durable ZnO nanoparticle antibacterial coating on flexible polymer substrates at room temperature. Substrates used are polystyrene, poly(ethylene-co-vinyl acetate) copolymer, poly(methyl methacrylate), polypropylene, high density polyethylene and a commercial acrylate type adhesive tape. The deposition was achieved by a spin-coating process using a slurry of ZnO nanoparticles in toluene. A stable modification layer was obtained when toluene was a solvent for the polymer substrates, namely polystyrene and poly(ethylene-co-vinyl acetate). These coatings show high antibacterial efficiency causing >5 log decrease in the viable counts of Gram-negative bacteria Escherichia. coli and Gram-positive bacteria Staphylococcus aureus in 120 min. Even after tapping these coated surfaces 500 times, the antibacterial properties remained unchanged, showing that the coating obtained by the presented method is very robust. In contrast to the above findings, the coatings are unstable when toluene is not a solvent for the substrate. 相似文献
73.
Jingyi Kong Yangyang Wang Ying Wu Liang Zhang Min Gong Xiang Lin Dongrui Wang 《Molecules (Basel, Switzerland)》2022,27(23)
The lack of suitable lightweight current collectors is one of the primary obstacles preventing the energy density of aqueous lithium-ion batteries (ALIBs) from becoming competitive. Using silver nanowire (AgNW) films as current collectors and a molecular crowding electrolyte, we herein report the fabrication of ALIBs with relatively good energy densities. In the 2 m LiTFSI–94% PEG–6% H2O solution, the AgNW films with a sheet resistance of less than 1.0 ohm/square exhibited an electrochemical stability window as broad as 3.8 V. The LiMn2O4//Li4Ti5O12 ALIBs using AgNW films as the current collectors demonstrated an initial energy density of 70 Wh/kg weighed by the total mass of the cathode and anode, which retained 89.1% after 50 cycles. 相似文献
74.
75.
以Zn(NO3)2· 6H2O和C6H12N4为原材料,采用二步水热法在碳纤维布上合成了形貌尺寸均匀的ZnO超细纳米线阵列。用 X 射线衍射(XRD)和扫描电镜(SEM)对其晶体结构和形貌进行了表征,利用恒流充放电测试等手段对其进行电化学性能测试。测试结果表明,材料表现出优异的电化学性能。在200 mA/g的电流密度下循环150次后,ZnO超细纳米线阵列仍然约有730 mAh/g的充放电比容量,库伦效率保持在95%以上。在1 200 mA/g的大倍率条件下,材料的充放电比容量依旧可达481 mAh/g左右,表现出十分良好的循环稳定性和可逆性能,是一种较为理想的锂离子电池负极复合材料。 相似文献
76.
磁控溅射制备ZnO薄膜的结构及发光特性研究 总被引:2,自引:0,他引:2
采用射频反应磁控溅射法在玻璃衬底上制备出具有c轴高择优取向的ZnO薄膜,利用X射线衍射、扫描探针显微镜及荧光分光光度法研究了生长温度对ZnO薄膜微观结构及光致发光特性的影响。结果表明,合适的衬底温度有利于提高ZnO薄膜的结晶质量;在室温下测量样品的光致发光谱(PL),观察到波长位于400 nm左右的紫光、446 nm左右的蓝色发光峰及502 nm左右微弱的绿光峰,随衬底温度升高,样品的PL谱中紫光及蓝光强度逐渐增大,同时,绿光峰的强度也表现出一定程度的增强。经分析得出紫光应是激子发光所致,而锌填隙则是引起蓝光发射的主要原因,502 nm左右的绿光峰应该是氧的深能级缺陷造成的。此外,还测量了样品的吸收谱,并结合样品吸收谱的拟合结果对光致发光机理的分析作了进一步的验证。 相似文献
77.
运用第一性原理方法研究了Cu/Ag单掺及Cu-Ag共掺对ZnO稳定性、电子结构和光学性质的影响。CuZn2和CuZn1-CuZn3的形成能接近0.0 eV,CuZn1-CuZn2的形成能为负值,表明Cu较易掺杂且掺杂时有聚集的趋势。AgZn2的形成能为2.5 eV,AgZn1-AgZn2和AgZn1-AgZn3的形成能高于4.5 eV,说明高浓度的Ag掺杂在实际合成中不易出现。CuZn1-AgZn2和CuZn1-AgZn3的形成能与AgZn2的相近。CuZn2、CuZn1-CuZn2和CuZn1-CuZn3模型的Cu3d与O2p轨道有较大程度的杂化,价带... 相似文献
78.
Mohamed Morsy Ahmed I. Abdel-Salam Islam Gomaa Hesham Moustafa Haitham Kalil Ahmed Helal 《Molecules (Basel, Switzerland)》2023,28(1)
The demand for reactive dyes in industries has increased rapidly in recent years, and producing a large quantity of dye-containing effluent waste contaminates soils and water streams. Current efforts to remove these harmful dyes have focused on utilizing functionalized nanomaterials. A 3D polyurethane foam loaded with reduced graphene oxide (rGO) and ZnO nanocomposite (PUF/rGO/ZnO) has been proposed as an efficient structural design for dye degradation under the influence of visible light. The proposed structure was synthesized using a hydrothermal route followed by microwave irradiation. The resultant 3D PUF/rGO/ZnO was examined and characterized by various techniques such as XRD, FTIR, SEM, EDAX, BET, and UV–visible spectroscopy. SEM data illustrated that a good dispersion and embedment of the rGO/ZnO NPs within the PUF matrix occurred. The adsorption capacity for neat PUF showed that around 20% of the Methylene blue (MB) dye was only adsorbed on its surface. However, it was found that an exceptional adsorption capacity for MB degradation was observed when the rGO/ZnO NPs inserted into the PUF, which initially deteriorated to ~ 70 % of its initial concentration. Notably, the MB dye was completely degraded within 3 h. 相似文献
79.
通过环境友好的葡萄糖模板法和改进的湿化学还原法制备了聚二甲基硅氧烷/铜纳米线(PDMS/CuNWs)复合薄膜, 其采用的“类夹心结构”有效解决了铜在空气中易氧化进而导致电导率大幅度下降的问题, 同时获得了具有优异电磁屏蔽和光热转化性能的双功能轻质柔性复合薄膜. CuNWs面密度为1.6 g/cm2的复合薄膜在重复弯折1000次后性能保持率最高可达99.07%; CuNWs面密度为2.4 g/cm2的复合薄膜在X波段下总电磁屏蔽效能达到30.1 dB, 屏蔽效率达到99.9%; 同时, 在2 W/cm2的近红外光照射下, 复合薄膜在仅加热15 s后其表面温度高达211.2 ℃, 具有十分快速的光热响应和转化效率. 相似文献
80.
Yu Fu Yanyan Yang Dongxue Chu Zefeng Liu Lili Zhou Xiaoyang Yu Xiaoshu Qu 《Molecules (Basel, Switzerland)》2022,27(13)
Polyoxometalates (POMs) demonstrate potential for application in the development of integrated smart energy devices based on bifunctional electrochromic (EC) optical modulation and electrochemical energy storage. Herein, a nanocomposite thin film composed of a vanadium-substituted Dawson-type POM, i.e., K7[P2W17VO62]·18H2O, and TiO2 nanowires were constructed via the combination of hydrothermal and layer-by-layer self-assembly methods. Through scanning electron microscopy and energy-dispersive spectroscopy characterisations, it was found that the TiO2 nanowire substrate acts as a skeleton to adsorb POM nanoparticles, thereby avoiding the aggregation or stacking of POM particles. The unique three-dimensional core−shell structures of these nanocomposites with high specific surface areas increases the number of active sites during the reaction process and shortens the ion diffusion pathway, thereby improving the electrochemical activities and electrical conductivities. Compared with pure POM thin films, the composite films showed improved EC properties with a significant optical contrast (38.32% at 580 nm), a short response time (1.65 and 1.64 s for colouring and bleaching, respectively), an excellent colouration efficiency (116.5 cm2 C−1), and satisfactory energy-storage properties (volumetric capacitance = 297.1 F cm−3 at 0.2 mA cm−2). Finally, a solid-state electrochromic energy-storage (EES) device was fabricated using the composite film as the cathode. After charging, the constructed device was able to light up a single light-emitting diode for 20 s. These results highlight the promising features of POM-based EES devices and demonstrate their potential for use in a wide range of applications, such as smart windows, military camouflage, sensors, and intelligent systems. 相似文献