Nonvolatile memory devices based on ZnO/polyimide nanocomposite sandwiched between two C60 layers

The memory effects of a three-layer nonvolatile memory device Al/C₆₀/ZnO nanoparticles embedded in a polyimide (PI) layer/C₆₀/p-Si were investigated by using capacitance-voltage (C-V) measurements. Transmission electron microscopy and selected area electron diffraction pattern measurements showed that ZnO nanocrystals were formed inside the PI layer. The insertion of C₆₀ layer improved the charge trap state density in the ZnO nanoparticle. The density was estimated by the flatband voltage shift in the C-V hysteresis, which increases with the max sweep voltage. Possible operating mechanisms corresponding to the charging and discharging process in the structure are proposed on the basis of the C-V results.     

ZnO纳米棒阵列的水热生长条件对柔性染料敏化太阳能电池的影响

利用水热法在不同条件下在ITO-PET(tin-doped indium oxide polyethylene terephthalate)上制备氧化锌纳米棒阵列, 通过一些定量的参数, 如纳米棒的直径、长度和棒密度来表征纳米棒的形貌. 通过改变反应条件可以调节上述参数. 分别讨论了两个重要条件: 反应时间和前驱体浓度. 研究表明前驱体浓度对长径比有重要影响. 柔性基底上的氧化锌纳米棒作为染料敏化电池的新型光阳极, 长径比的改变对柔性电池有重要的影响. 可通过调节反应条件来提高柔性染料敏化电池的性能.     

基于ZnO纳米片多级结构的柔性染料敏化太阳能电池的制备

采用水热合成法制备基于钛箔的ZnO纳米片薄膜, 采用化学浴沉积法在ZnO纳米片薄膜表面原位沉积ZnO纳米粒和微球, 制备了ZnO纳米片/纳米粒/微球复合结构薄膜, 并将膜组装成柔性染料敏化太阳能电池。研究了钛箔预处理方式、化学浴沉积工艺对ZnO薄膜和电池性能的影响。采用X射线衍射仪、透射电子显微镜和扫描电子显微镜对钛箔和ZnO薄膜的物相组成和形貌进行表征, 采用太阳光模拟器和数字源表测试了电池的J-V光电性能曲线, 通过电化学阻抗谱分析了电池内部电子传输情况。研究结果表明: 当钛箔基底采用酸抛光处理, 将所得ZnO纳米片膜用已经预热24 h的0.15 mol/L二水乙酸锌甲醇溶液改性5 h, 所得电池光电性能最好, 其短路电流密度、开路电压、填充因子和光电转化率分别为11.26 mA/cm², 0.67 V, 0.60和4.51%。     

纺锤形氧化锌的水热制备及其对三乙胺的气敏性能

采用水热法,用氨水调节溶液pH,合成了纺锤及花状的ZnO。利用X射线衍射仪、扫描电子显微镜对不同pH下合成的ZnO的物相及形貌进行了表征,并采用静态配气法测试了其对三乙胺的气敏性能。结果表明,不同pH制备了不同形貌的ZnO材料。pH=9时制备的纺锤形ZnO对三乙胺的灵敏度最高,在340℃的最佳工作温度下对100mg/L三乙胺气体的灵敏度高达90.0,呈现出良好的选择性。并且元件具有较好的响应-恢复特性,响应时间为27s,恢复时间仅需3s。     

ZnO纳米棒阵列、纳米片及其发光和光催化特性

首先通过溶胶-凝胶法在Si片基底上制备1层ZnO纳米薄膜,作为纳米棒的晶种层,然后利用金属浴沉积法在ZnO纳米薄膜基础上制备择优取向的ZnO纳米棒阵列,最后通过水热法二次成核结晶形成纳米片。研究证明,ZnO纳米棒阵列和纳米片均沿着c轴取向。在Cu2+抑制极性面生长的作用下,形成的ZnO纳米片结构均匀,分布面积广,单片ZnO纳米片的厚度约为8 nm,面积呈平方微米级,较大的有40μm2左右。ZnO纳米结构的生长取向对其物理化学性能具有重要影响。高度沿c轴取向的ZnO纳米棒有利于紫外光发射和激光器的发展,但极性面的缩小不利于光催化反应。     

Flexible piezoelectric nanogenerators based on a fiber/ZnO nanowires/paper hybrid structure for energy harvesting

We present a novel, low-cost approach to fabricate flexible piezoelectric nano- generators （NGs） consisting of ZnO nanowires （NWs） on carbon fibers and foldable Au-coated ZnO NWs on paper. By using such designed structure of the NGs, the radial ZnO NWs on a cylindrical fiber can be utilized fully and the electrical output of the NG is improved. The electrical output behavior of the NGs can be optionally controlled by increasing the fiber number, adjusting the strain rate and connection modes. For the single-fiber based NGs, the output voltage is 17 mV and the current density is about 0.09 μA·cm^-2, and the electrical output is enhanced greatly compared to that of previous similar micro-fiber based NGs. Compared with the single-fiber based NGs, the output current of the multi-fiber based NGs made of 200 carbon fibers increased 100-fold. An output voltage of 18 mV and current of 35 nA are generated from the multi-fiber based NGs. The electrical energy generated by the NGs is enough to power a practical device. The developed novel NGs can be used for smart textile structures, wearable and self-powered nanodevices.     

氧化锌/氧化镁纳米复合材料的制备及其光催化性能研究

采用微波辅助共沉淀法制备了纳米氧化锌/氧化镁(ZnO/MgO)光催化剂,并对催化剂样品进行了X射线衍射、透射电镜、红外光谱以及紫外-可见吸收光谱等表征。以亚甲基蓝(MB)为目标降解物对不同锌镁比的ZnO/MgO催化剂样品及相同方法下合成的ZnO及MgO进行光催化降解实验。结果表明:合成的纳米ZnO/MgO光催化剂由立方相的ZnO和非晶相的MgO组成,其尺寸均匀,在40nm左右,并在紫外区域吸收性能良好。光催化降解MB实验表明,锌镁比为2∶1时ZnO/MgO催化剂的光催化性能最佳。     

Fabrication and Characterization of Undoped and Cobalt-doped ZnO Based UV Photodetector Prepared by RF-sputtering

Undoped and 1 at.% Co-doped ZnO nanostructure based UV photodetectors were successfully fabricated by RF- magnetron sputtering technique with comb like Pt electrodes. Cobalt ions were successfully incorporated into the lattice of the ZnO nanostructure without changing its wurtzite structure. It was indicated that Co-doping can effectively adjust the luminescence properties of the ZnO nanostructure. The undoped and Co-doped ZnO photodetectors were observed to have photosensitivities of 1.44 x 104 % and 8.57 x 102 % and low dark currents of 9.74 x 10-8 A and 1.18 x 10-7 A, respectively.     

Hybrid nanocomposite based on cellulose and tin oxide: growth,structure, tensile and electrical characteristics

Abstract

A highly flexible nanocomposite was developed by coating a regenerated cellulose film with a thin layer of tin oxide (SnO₂) by liquid-phase deposition. Tin oxide was crystallized in solution and formed nanocrystal coatings on regenerated cellulose. The nanocrystalline layers did not exfoliate from cellulose. Transmission electron microscopy and energy dispersive x-ray spectroscopy suggest that SnO₂ was not only deposited over the cellulose surface, but also nucleated and grew inside the cellulose film. Current–voltage characteristics of the nanocomposite revealed that its electrical resistivity decreases with deposition time, with the lowest value obtained for 24 h of deposition. The cellulose–SnO₂ hybrid nanocomposite can be used for biodegradable and disposable chemical, humidity and biosensors.     

Morphology and optoelectronic properties of ZnO rod array/conjugated polymer hybrid films

Vertically aligned zinc oxide (ZnO) nanorods were grown on the ITO glass and then coated with the conjugated polymer poly(2,3-dibutoxy-1,4-phenylene vinylene) (DB-PPV) to make the hybrid films. Nanorods with different diameters were synthesized to study the influences of ZnO nanorod morphology and polymer infiltration on the photocurrent and optical properties of the hybrid films. Increasing the growth time leads to the formation of ZnO rod array with large rod diameter, large surface area and small inter-rod distance. Small inter-rod distance hinders the filling of DB-PPV into the porous ZnO rod microstructure and lowers the PN junction area. It leads to lower photocurrent of the hybrid film. The red shift of the photoluminescence spectra suggests that filling the polymer into the ZnO rod microstructure favors more planar molecular orientations of the conjugated polymers and leads to an increase in the effective conjugation length.     

Hybrid nanocomposite based on cellulose and tin oxide: growth,structure, tensile and electrical characteristics

A highly flexible nanocomposite was developed by coating a regenerated cellulose film with a thin layer of tin oxide (SnO₂) by liquid-phase deposition. Tin oxide was crystallized in solution and formed nanocrystal coatings on regenerated cellulose. The nanocrystalline layers did not exfoliate from cellulose. Transmission electron microscopy and energy dispersive x-ray spectroscopy suggest that SnO₂ was not only deposited over the cellulose surface, but also nucleated and grew inside the cellulose film. Current–voltage characteristics of the nanocomposite revealed that its electrical resistivity decreases with deposition time, with the lowest value obtained for 24 h of deposition. The cellulose–SnO₂ hybrid nanocomposite can be used for biodegradable and disposable chemical, humidity and biosensors.     

ZnO／Ag纳米复合抗菌剂的分散与性能研究

以XRD、TEM、激光粒度分布对自制ZnO／Ag纳米复合抗菌剂进行表征，对其抗菌、抗藻和安全性能进行检测。结果表明：经PAAS分散后，ZnO／Ag纳米复合抗菌剂的团聚程度大大降低，分散剂PAAS的加入质量分数对ZnO／Ag纳米复合抗菌剂分散效果的影响呈抛物线状，最佳加入质量分数为48％，平均粒径为11．8nm。ZnO／Ag纳米复合抗菌剂具有优良的抗菌、抗藻和安全性能，对大肠埃希氏菌和金黄色葡萄球菌的最小抑菌浓度均为50mg／L，对小球藻菌的最小抑菌浓度为5mg／L，对小鼠的急性经口毒性的LD50为9260mg／kg，对皮肤无刺激性。     

Microwave sintering of ZnO nanopowders and characterization for gas sensing

Thick ?lm gas sensors based on ZnO nanopowders were fabricated by using microwave sintering. The surface and cross section morphologies were characterized by ?eld-emission scanning electron microscopy (FE-SEM). The stability of the microstructure was studied by impedance spectroscopy. The results showed that the shape of the nanoparticles was not changed through microwave sintering, and the thick films had the more dense microstructures than that by muffle oven sintering. The resistance-temperature characteristic and the responses to toluene, methanol and formaldehyde revealed that the microwave sintering technique could effectively control the growth of ZnO nanoparticles, realize the uniform sintering of thick film, gain the stable microstructure and improve the response of sensor. In addition, the formative mechanism of the thick film microstructure was proposed according to microwave sintering mechanism.     

涂料用纳米氧化锌/聚醋酸乙烯酯的制备及抗紫外性能

ZnO抗老化性能优良,聚醋酸乙烯酯(PVAc)热塑性好,由两者制成的复合材料具有优异的抗紫外性能,用于涂料可以提高抗老化性能.以ZnSO4和尿素为原料,用水解法制得纳米ZnO溶胶,将ZnO溶胶分散于PVAc-丙酮溶液中,制得无色透明的纳米ZnO/PVAc复合溶胶,再将两者合成无色透明的ZnO/PVAc复合膜.结果表明:ZnO在PVAc中分布均匀,形态一致;ZnO含量低于2.0%o时,ZnO/PVAc中纳米颗粒粒径在20～30 nm范围内,平均密度为27.4 nm,体积平均为27.8 nm,数均25.4 nm;与纯PVAc溶液相比,最大吸收峰蓝移了13.2 nm;复合材料中ZnO含量仅0.65%o时,吸光度增大近1倍,且随材料中ZnO含量的增加而增大.     

MOF-derived ZnO and ZnO@C composites with high photocatalytic activity and adsorption capacity

Nanostructured ZnO materials have unique and highly attractive properties and have inspired interest in their research and development. This paper presents a facile method for the preparation of novel ZnO-based nanostructured architectures using a metal organic framework (MOF) as a precursor. In this approach, ZnO nanoparticles and ZnO@C hybrid composites were produced under several heating and atmospheric (air or nitrogen) conditions. The resultant ZnO nanoparticles formed hierarchical aggregates with a three-dimensional cubic morphology, whereas ZnO@C hybrid composites consisted of faceted ZnO crystals embedded within a highly porous carbonaceous species, as determined by several characterization methods. The newly synthesized nanomaterials showed relatively high photocatalytic decomposition activity and significantly enhanced adsorption capacities for organic pollutants.     

Selective growth of ZnO nanorods for gas sensors using ink-jet printing and hydrothermal processes

Selective growth of ZnO nanorod arrays with well-defined areas was developed to fabricate the NO₂ gas sensor. The seed solution was ink-jet printed on the interdigitated electrodes. Then, vertically aligned ZnO nanorods were grown on the patterned seed layer by the hydrothermal approach. The influences of seed-solution properties and the ink-jet printing parameters on the printing performance and the morphology of the nanorods were studied. Round micropattern (diameter: 650 μm) of ZnO nanorod arrays is demonstrated. The dimensions and positions of the nanorod arrays can be controlled by changing the printed seed pattern. The effects of nanorod structure and nanorod size on the gas-sensing capability of ZnO nanorod gas sensors were demonstrated. Due to the high surface-to-volume ratios of the nanorod-array structure, the ZnO nanorod gas sensor can respond to 750 ppb NO₂ at 100 °C. The sensors without baking treatment exhibit the typical response of a p-type semiconductor. However, only the response of n-type semiconductor oxides was observed after the annealing treatment at 150 °C for 2 h.     

纳米SnO2、ZnO及ZnO／SnO2复合材料的气敏性能研究

以ZnO、S如纳米颗粒及ZnO／SnO2复合纳米材料分别作为气敏基料制成旁热式气敏元件,运用扫描电镜观察产物的形貌,用静态配气法对浓度为100ppm的甲烷气体进行气敏性能的测试。结果表明,这几类元件的最佳工作温度及灵敏度差异较大,当工作温度为350℃时SnO2纳米颗粒的气敏性能最佳。此温度下,SnO2响应时间和恢复时间也比纯ZnO纳米颗粒分别缩短了2S和3S。     

AZO晶种层对ZnO纳米线生长及紫外光电导性能的影响

采用溶液化学法实现了在Zn(NO3)2/C6H12N4混合溶液中ZnO纳米线在AZO薄膜修饰过衬底上生长。AZO薄膜由射频磁控溅射法制备,通过溅射时间和基底温度的变化改变薄膜形态,重点研究了不同薄膜形态对ZnO纳米线形貌和结构的影响,最终在溅射2h、基底温度250℃晶种上得到垂直于衬底、高度平行取向的ZnO纳米线阵列。在此基础上研究了不同形貌ZnO纳米线阵列的紫外光电导性能差异。结果表明,垂直生长的纳米线较倒伏纳米线紫外响应迅速,分析认为是紫外光照下曝光面积不同造成的。     

Immobilization of ZnO on Chitosan-Neem seed composite for enhanced thermal and antibacterial activity

Natural and inorganic materials of Chitosan-Zinc oxide-Neem seed (CS-ZnO-NS) hybrid composite were synthesized by chemical precipitation method. The obtained CS-ZnO-NS hybrid composites were characterized for functional group confirmation by Fourier transform infrared spectroscopy and UV–Visible spectroscopy. The ZnO particles connected to biopolymers exhibited small grains and rod, bullet like structure confirmed by scanning electron microscopy and transmission electron microscopy analysis. The size of the prepared CS-ZnO-NS hybrid composite was found to be 20–80?nm. The crystalline behaviors were determined by X-ray diffraction analysis. The surface area of the prepared hybrid composite was determined using BET analysis. The elemental composition was analyzed by energy dispersive X-ray spectroscopy and thermal behaviors by thermo gravimetric analysis. The obtained result shows that zinc oxide was well able to incorporate into chitosan-neem seed composite which enhances the thermal stability. Further, the antibacterial activity evaluated by agar well diffusion method against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria exhibits higher inhibition effect because of ZnO particles presence in the chitosan-neem seed. Hence the CS-ZnO-NS is a promising material for biomedical applications.