衬底温度对ZnO纳米结构的影响

利用超声喷雾热解(USP)技术,以普通玻璃为衬底,制备了不同衬底温度下的系列ZnO薄膜.用扫描电镜(SEM)和X射线衍射(XRD)研究了衬底温度对ZnO结构的影响.结果表明,薄膜的微观结构随衬底温度变化显著.在410℃获得了ZnO纳米棒,纳米棒直径在50 nm左右,沿c轴择优生长,结晶质量较好.     

Ultraviolet photoresponse of ZnO nanostructured AlGaN/GaN HEMTs

We present the first active visible blind ultraviolet (UV) photodetector based on zinc oxide (ZnO) nanostructured AlGaN/GaN high electron mobility transistors (HEMTs). The ZnO nanorods (NRs) are selectively grown on the gate area by using hydrothermal method. It is shown that ZnO nanorod (NR)-gated UV detectors exhibit much superior performance in terms of response speed and recovery time to those of seed-layer-gated detectors. It is also found that the best response speed (~10 and~190 ms) and responsivity (~1.1×10⁵ A/W) were observed from detectors of the shortest gate length of 2 µm among our NR-gated devices of three different gate dimensions, and this responsivity is about one order higher than the best performance of ZnO NR-based UV detectors reported to date.     

Metal hydride batteries research using nanostructured additives

We describe here, our recent research efforts to improve the capacity of metal hydride batteries using nanostructured additives. Nanostructured additives of palladium, copper and nickel were incorporated separately into the negative electrode of the metal hydride batteries. The nanomaterials were synthesized by template-based methods and characterized by scanning electron microscopy. These nanomaterials were incorporated in the negative electrode of the metal hydride battery and the electrochemical performance at 2 C rate was studied. The nanomaterial-incorporated negative electrodes all showed increased cell voltage and negative electrode potential compared to that of a pristine cell. The increase in discharge capacity for a cut-off voltage of 1 V depends on the nanomaterial incorporated and a comparative analysis of the performance of the different batteries is presented.     

Fabrication of ZnO/SrTiO3 nanoarrays and its photoelectrochemical performances

The ZnO/SrTiO₃ nanomaterials were fabricated by a chemical conversion hydrothermal method in order to utilize the high electron transfer rate of one-dimensional ZnO nanorods and photocatalytic activity of SrTiO₃. The technological parameters, such as TiO₂ sol concentration, TiO₂ sol dipping cycle, Sr(NO₃)₂ concentration and reaction temperature, were investigated in the synthetic process and the reaction mechanism of the ZnO/SrTiO₃ nanomaterials was proposed. A photocurrent density of 7.53 mA/cm² was obtained for the as-prepared ZnO/SrTiO₃ photocatalyst, attributed to its improved absorption spectrum and appropriate nanostructure, which indicates a potential application in photoelectrochemical water splitting.     

Facile synthesis and catalytic properties of single crystalline β-MnO2 nanorods

Single-crystalline β-MnO₂ nanorods were successfully synthesized through facile reflux treatment of KMnO₄ and MnSO₄ in HNO₃ solution. TEM and SEM images show that the synthesized β-MnO₂ nanorods exhibited diameters of 20–50 nm, and lengths that ranged from approximately 0.5 to 2.0 μm with decreasing HNO₃ concentrations from 0.8 to 0.1 mol/L. The β-MnO₂ nanorods underwent three primary evolutionary stages over time. They exhibited excellent catalytic properties for the degradation of methylene blue (MB) by a Fenton-like reaction.     

稀土氢氧化镝纳米棒的水热合成及生长机理研究

本文介绍了一种水热合成稀土Dy(OH)3纳米棒的方法,反应条件温和,绿色环保,无污染.在水热过程中,以氧化镝粉末为反应前驱体,氢氧化钾为矿化剂,水为溶剂,180℃条件下水热48 h,合成了稀土Dy(OH)3纳米棒,再经过500℃热处理1h,即可得到同形貌的Dy2O3纳米材料.通过X射线粉末衍射(XRD)仪、透射电镜(TEM)对样品进行表征,结果表明,所制得的稀土Dy(OH)3为结晶良好、粒径均一、表面光滑的棒状纳米结构.同时,本文对矿化剂对产物形貌的影响进行了探讨.     

喷雾燃烧制备SnO2纳米棒及其气敏性能

采用喷雾燃烧法制备SnO2纳米棒,对其形貌和结构进行了表征. 所制SnO2纳米棒长200~350 nm,直径30~50 nm,沿(001)方向生长. 考察了Fe掺杂量和Sn4+浓度对SnO2纳米棒形貌的影响,分析了其生长机理. 高温快速反应使Fe3+进入SnO2晶格,促使其沿(001)方向取向生长. 对乙醇等有机气体的气敏性能测试结果表明,棒状SnO2比颗粒状的具有更优的气敏性能,在100′10-6(j)乙醇浓度下,棒状SnO2的灵敏度为12,反应和恢复时间分别为9.5和6 s.     

Influence of Y-doped induced defects on the optical and magnetic properties of ZnO nanorod arrays prepared by low-temperature hydrothermal process

ABSTRACT: One-dimensional pure zinc oxide (ZnO) and Y-doped ZnO nanorod arrays have been successfully fabricated on the silicon substrate for comparison by a simple hydrothermal process at the low temperature of 90°C. The Y-doped nanorods exhibit the same c-axis-oriented wurtzite hexagonal structure as pure ZnO nanorods. Based on the results of photoluminescence, an enhancement of defect-induced green-yellow visible emission is observed for the Y-doped ZnO nanorods. The decrease of E2(H) mode intensity and increase of E1(LO) mode intensity examined by the Raman spectrum also indicate the increase of defects for the Y-doped ZnO nanorods. As compared to pure ZnO nanorods, Y-doped ZnO nanorods show a remarked increase of saturation magnetization. The combination of visible photoluminescence and ferromagnetism measurement results indicates the increase of oxygen defects due to the Y doping which plays a crucial role in the optical and magnetic performances of the ZnO nanorods.     

Fabrication of urchin-like ZnO-MXene nanocomposites for high-performance electromagnetic absorption

The recently developed two-dimensional transition metal carbides (such as MXene) have shown amazing electrical properties. MXene and derivative two dimensional (2D) materials are widely used in electron devices, and have large potential application in electromagnetic (EM) absorber. Herein we describe a mild method to prepare an urchin-like ZnO-MXene Ti₃C₂T_x nanocomposite through a coprecipitation process. The nanocomposite delivers a substantially enhanced EM absorbing performance with an optimum reflection loss of −26.30 dB, which is significantly better than that of primitive Ti₃C₂T_x (−6.70 dB), owing to the construction of unique semiconductive networks and larger interfaces. The EM absorption performance can be effectively controlled in the range of 14.0–18.0 bands by changing the growth time of ZnO. Considering the large amount of members in MXene, this study demonstrates a new strategy applicable in maximizing their applications in EM absorbing materials.     

Effect of Al doped ZnO on optical and photovoltaic properties of the p-Cu2O/n-AZO solar cells

Metal oxide thin films have fared so well in the semiconductor industry because of their superior physical, electrical, and optical properties. The applications of these materials in solar cells, biosensors, biomedicine, supercapacitors, photocatalysis, luminous materials, and laser systems are becoming increasingly popular. In this study, the influence of Al concentration on Cu₂O/AZO heterojunction thin films was examined systematically. First, arrays of n-ZnO and AZO rods were produced on an ITO substrate using a hydrothermal technique at 140 °C. Then, using an alkaline cupric lactate solution, a thin films of p-Cu₂O were electrodeposited at 60 °C onto the ZnO arrays. The structure and morphology of the produced materials and the solar cells were studied using X-ray diffraction and scanning electron microscopy. The optical measurements demonstrate a shift in the absorption edge with increasing Al content. Solar cells have been created with a device structure of ITO/ZnO/Cu₂O/Al and ITO/Al-doped ZnO/Cu₂O/Al configurations. The power conversion efficiency (?) of the inorganic solar cell with 6% Al-doped ZnO is ? = 0.282%, which is greater than the ? of the ZnO-based solar cell (? = 0.17%).