ZnS/ZnO纳米片组装的多孔微球的制备及光催化性能研究

将水热法制备的ZnS纳米球500℃下保温2h制备出由ZnS、ZnO纳米片组装的多孔微球。利用扫描电子显微镜、X射线衍射仪、透射电子显微镜、紫外-可见近红外分光光度计和紫外-可见分光光度计等对样品的形貌、结构和光学性能进行了表征。以甲基橙(MO)的光催化降解为目标反应,评价其光催化活性。ZnS/ZnO异质结材料的带隙明显窄于ZnO,光催化活性得到提高;经60 min紫外光照射后,ZnS/ZnO异质结催化剂对MO的降解率为76%。最后分析和探讨了异质结催化剂的光催化机理。     

One-dimensional protuberant optically active ZnO structure fabricated by oxidizing ZnS nanowires

High crystalline quality ZnS nanowires were fabricated using the thermal evaporation method. They were then oxidized in air at different temperatures to form a one-dimensional protuberant ZnO/ZnS structure. It was argued that the oxidation at low enough temperature can significantly improve the quality of the ZnS nanowires by passivating dangling bonds on the nanowire surface as the absorption of oxygen atoms. This study provides a simple approach for synthesizing optically active ZnO/ZnS heterostructures.     

Fabrication of single-crystal ZnO nanorods and ZnS nanotubes through a simple ultrasonic chemical solution method

A simple and rapid method has been developed for the preparation of rod-like ZnO nanocrystals via ultrasonic irradiation. The as-synthesized ZnO nanocrystals were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). The ZnO nanorods had an average diameter of 15-70 nm that varied from the ultrasonic operation mode. The results showed that Zn powder played an important role in the synthesis of ZnO nanorods. Through adding a sulfur source in the reaction system, ZnO/ZnS nanocables and ZnS nanotubes could be obtained with continuous ultrasonic irradiation. The formation mechanism of ZnS nanotubes could be attributed to the Kirkendall effect.     

Preparation and characterization of ZnO/ZnS core/shell nanocomposites through a simple chemical method

In this paper, we reported the preparation of ZnO/ZnS core/shell nanocomposites by sulfidation of ZnO nanostructures via a simple hydrothermal method. The precursors of bare ZnO nanoparticles and ZnO nanorods were synthesized by a surfactant-assisted hydrothermal growth. The structural, morphological, and element compositional analysis of bare ZnO nanostructures and ZnO/ZnS core/shell nanocomposites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy techniques. The XRD results indicated that the phase of bare ZnO nanoparticles and ZnO nanorods was wurtzite structure, and the phase of coated ZnS nanoparticles on the surface of bare ZnO nanostructures was sphalerite structure with the size of about 8 nm. Photoluminescence measurement was carried out, and the PL spectra of ZnO/ZnS core/shell nanocomposites revealed an enhanced UV emission and a passivated orange emission compared to that of bare ZnO nanostructures. In addition, the growth mechanism of ZnO/ZnS core/shell nanostructures through hydrothermal method was preliminarily discussed.     

自供能ZnO/ZnS异质结紫外探测器的性能研究

用化学浴法在ZnO纳米棒表面沉积ZnS制备出ZnO/ZnS核壳纳米棒阵列,使用SEM、XRD和XPS等手段表征了样品的形貌、结构和成分。结果表明,ZnO/ZnS核壳纳米棒阵列表面粗糙,生长致密、分布均匀,其平均直径约为150 nm。以Pt为对电极组装的自供能ZnO/ZnS异质结紫外探测器,对紫外光具有很好的探测性能,能循环工作且性能稳定。这种探测器对微弱的紫外光也有较强的响应和较高的光敏性,且随着光强度的提高光电流密度线性增大。与自供能ZnO纳米棒紫外探测器相比,ZnO/ZnS异质结紫外探测器具有更高的响应速度,上升时间和下降时间分别提高到0.02 s和0.03 s。     

氧化锌纳米阵列场发射性能研究

采用物理气相沉积的方法通过控制生长参数，在硅衬底上获得不同形貌的氧化锌纳米阵列。在金属场发射系统中测量了它们的场致电子发射性能，发现阴极发射电流不稳定主要是由于氧化锌纳米阵列的不均匀性造成的．采用高压励炼技术可以增强氧化锌场发射的稳定性，使电流波动明显降低．此外，形貌对氧化锌纳米阵列的场发射电流密度和阈值电压有明显影响，而且不同形貌的氧化锌纳米阵列的抗溅射能力也不相同．     

Core/Shell ZnO/ZnS Nanoparticle Electron Transport Layers Enable Efficient All-Solution-Processed Perovskite Light-Emitting Diodes

Solution-processed perovskite-based light-emitting diodes (PeLEDs) are promising candidates for low-cost, large-area displays, while severe deterioration of the perovskite light-emitting layer occurs during deposition of electron transport layers from solution in an issue. Herein, core/shell ZnO/ZnS nanoparticles as a solution-processed electron transport layer in PeLED based on quasi-2D PEA₂Cs_n−1Pb_nBr_3n+1 (PEA = phenylethylammonium) perovskite are employed. The deposition of ZnS shell mitigates trap states on ZnO core by anchoring sulfur to oxygen vacancies, and at the same time removes residual hydroxyl groups, which helps to suppress the interfacial trap-assisted non-radiative recombination and the deprotonation reaction between the perovskite layer and ZnO. The core/shell ZnO/ZnS nanoparticles show comparably high electron mobility to pristine ZnO nanoparticles, combined with the reduced energy barrier between the electron transport layer and the perovskite layer, improving the charge injection balance in PeLEDs. As a result, the optimized PeLEDs employing core/shell ZnO/ZnS nanoparticles as a solution-processed electron transport layer exhibit high peak luminance reaching 32 400 cd m⁻², external quantum efficiency of 10.3%, and 20-fold extended longevity as compared to the devices utilizing ZnO nanoparticles, which represents one of the highest overall performances for solution-processed PeLEDs.     

Plasmon enhancement for Vernier coupled single-mode lasing from ZnO/Pt hybrid microcavities

It is essential to develop a single mode operation and improve the performance of lasing in order to ensure practical applicability of microlasers and nanolasers.In this paper,two hexagonal microteeth with varied nanoscaled air-gaps of a ZnO microcomb are used to construct coupled whispering-gallery cavities.This is done to achieve a stable single mode lasing based on Vernier effect without requiring any complicated or sophisticated manipulation to achieve positioning with nanoscale precision.Optical gain and the corresponding ultraviolet lasing performance were improved greatly through coupling with localized surface plasmons of Pt nanoparticles.The ZnO/Pt hybrid microcavities achieved a seven-fold enhancement of intensity of single mode lasing with higher sidemode suppression ratio and lower threshold.The mechanism that led to this enhancement has been described in detail.     

Blue-shifted stimulated emission from ZnO films deposited on SiO2 by atomic layer deposition

ZnO films were prepared by atomic layer deposition upon a SiO₂ layer on a Si substrate and treated by rapid thermal annealing. The optically-pumped random lasing actions with low threshold values were observed in the ZnO films on SiO₂/Si substrates. With the decrease in ZnO film thickness or the increase in post-annealing duration, the stimulated emission shifted toward the shorter wavelength and the lasing threshold increased. The results can be attributed to the inter-diffusion between ZnO and SiO₂, which causes the modification of bandgap renormalization in ZnO.     

A ZnS/CaZnOS Heterojunction for Efficient Mechanical-to-Optical Energy Conversion by Conduction Band Offset

Actively collecting the mechanical energy by efficient conversion to other forms of energy such as light opens a new possibility of energy-saving, which is of pivotal significance for supplying potential solutions for the present energy crisis. Such energy conversion has shown promising applications in modern sensors, actuators, and energy harvesting. However, the implementation of such technologies is being hindered because most luminescent materials show weak and non-recoverable emissions under mechanical excitation. Herein, a new class of heterojunctioned ZnS/CaZnOS piezophotonic systems is presented, which displays highly reproducible mechanoluminescence (ML) with an unprecedented intensity of over two times higher than that of the widely used commercial ZnS (the state-of-the-art ML material). Density functional theory calculations reveal that the high-performance ML originates from efficient charge transfer and recombination through offset of the valence and conduction bands in the heterojunction interface region. By controlling the ZnS-to-CaZnOS ratio in conjunction with manganese (Mn²⁺) and lanthanide (Ln³⁺) doping, tunable ML across the full spectrum is activated by a small mechanical stimulus of 1 N (10 kPa). The findings demonstrate a novel strategy for constructing efficient ML materials by leveraging interface effects and ultimately promoting practical applications for ML.     

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。     

电场辅助溶液法制备氧化锌纳米棒阵列及其形貌研究

在外加电场辅助下用溶液法制备了氧化锌纳米棒阵列,反应过程低温、快速,且在无种子层条件下单步完成.用XRD和SEM表征了不同条件下制备的样品的结构和形貌,制备得到的氧化锌纳米棒尺寸均匀、生长致密,直径在50～200nm之间,长度1.5μm左右.分别研究了添加剂六亚甲基四胺(HMTA)和引入的辅助电场的作用及其对样品形貌的影响.研究了不同反应物浓度和反应时间下的样品形貌,讨论了纳米棒一星状双层氧化锌纳米结构在溶液中的形成和生长机理.     

微/纳米ZnO绒球的制备及光催化降解有机染料

以谷氨酸-氟硼酸(GluBF4)离子液体水溶液为反应介质,以物质的量比为1∶6的二水合醋酸锌[Zn(Ac)2·2H2O]和NaOH为原料,室温下制备前驱体,再微波辅助加热制备了微/纳米ZnO粉体,获得了单一形貌较高比表面积微/纳米ZnO绒球。利用扫描电镜(SEM)、X射线衍射(XRD)、比表面(BET)、能谱(EDS)等对产物进行了结构与性能表征。所得产物为六方晶系纤锌矿结构,绒球直径在1.6~3.0μm之间,粒径平均尺寸20.4nm,绒球比表面积为28.3m2/g,产物纯度高,收率95.6%。该纳米材料在自然光下表现出较高的光催化活性和形态稳定性。分别配制浓度为10mg/L的100mL甲基橙(methylorange,MO)、溴甲酚绿(bromocresolgreen,BG)水溶液,30mg纳米ZnO为光降解催化剂,太阳光激发下5h脱色率分别达74.3%和86.4%,重复利用5次,催化剂形貌不变、重量未发生变化。     

ZnS/TiO2聚砜纤维复合材料的制备及其光催化水制氢性能的研究

利用高压静电纺丝制备了具有良好耐光降解性能的羧基聚砜电纺纤维毡,利用其为载体用水热反应法制备了ZnS/TiO2聚砜复合光催化材料,得到了分布均匀的ZnS/TiO2聚砜纤维复合材料。通过X射线衍射、光电子能谱、紫外-可见漫反射光谱、热失重、耐紫外光降解实验对复合材料进行了表征。光催化分解水制氢实验表明:ZnS/TiO2含羧基聚砜纤维复合材料的催化效率高于同等条件下粉体ZnS/TiO2,并且具有很好的重复稳定性。     

金/硅纳米孔柱阵列的场发射

利用浸溃技术在硅纳米孔柱阵列(silicon nanoporous pillar array(简称Si-NPA))上制备了复合纳米薄膜Au/Si-NPA.测试了其场发射性能.测试结果显示,Au/Si-NPA的开启电场为约2V/μm;在7.59V/μm的外加电场下,其发射电流密度为67μA/cm2;在外加电压2000V时,其电流浮动率为21%.导致Au/Si-NPA优良的发射性能是由于其独特的表面形貌和结构所致.     

Shed light on submerged DC arc discharge synthesis of low band gap gray Zn/ZnO nanoparticles: Formation and gradual oxidation mechanism

Synthesis of colloidal metal oxides with controllable size and morphology is burgeoning field of research in nanoscience. Low band gap gray Zn/ZnO colloidal nanoparticles were fabricated by plasma-liquid interaction of DC arc discharge in water. Scanning electron microscopy, X-ray diffraction and UV–vis spectroscopy were employed for morphology, crystal structure and optical characterizations respectively. Optical emission spectroscopy was used to investigate the plasma properties during the synthesis and formation mechanism of nanoparticles. Nanoparticles with different size and shape were fabricated only by adjusting discharge current during synthesis without introducing any chemical agent. Electric discharge current was set to 20, 50, 100 and 150?A during synthesis. Estimated values of plasma excitation energies were 2.41, 2.66, 2.86 and 3.04?eV and diameter size of nanoparticles were 63, 42, 37 and 29?nm for these applied currents respectively. Synthesized nanoparticles were dark gray as prepared and became more transparent gradually getting white color finally. XRD and UV–vis results revealed that the oxidation process was time dependent. The colloidal nanoparticles composed of two metal and metal-oxide phase and white crystalline ZnO was achieved after complete oxidation process. These results provided a flexible and versatile method to synthesize metal oxide nanoparticles with controlled composition.