ZnO纳米线阵列的籽晶控制生长及其紫外探测性能

分别利用磁控溅射沉积、溶胶-凝胶浸涂及旋涂等方法在氧化铟锡(indium tin oxide,ITO)导电玻璃上得到籽晶层,然后通过低温水热法获得了ZnO纳米线阵列。通过X射线衍射、扫描电镜、透射电镜、光致发光谱等测试手段对不同方法获得的ZnO籽晶和纳米线阵列进行了表征和研究。进而在光刻有银电极的ITO玻璃基片上制备出紫外探测原型器件,测试了其紫外响应特性,并结合ZnO纳米线表面特性讨论了器件的紫外响应机理。结果表明:溶胶-凝胶旋涂获得的籽晶最小,生长出的纳米线长径比最高,直径最细,取向性也最好。对应的室温光致发光谱在近带边有优良的激发峰,而可见区的发光峰受到明显抑制。旋涂和浸涂籽晶获得的紫外探测样品响应迅速,但恢复较慢;磁控溅射籽晶样品有较优的响应和恢复特性,但信号强度较低。     

TiO_2/ZnO双层电子传输层的制备及光电化学性能

首先在氟掺杂的氧化锡导电玻璃(FTO)上水热生长一层TiO_2纳米棒阵列薄膜,然后通过旋涂法旋涂ZnO籽晶层后水热法生长ZnO纳米棒得到TiO_2/ZnO纳米棒阵列薄膜。通过XRD、SEM、PL、UV-Vis和电化学工作站等对单层TiO_2纳米棒和TiO_2/ZnO纳米棒的结构、表面形貌、荧光性能、光吸收强度以及光电化学性质进行表征。结果表明,随着水热生长ZnO时间的增长,ZnO纳米棒密度增加; ZnO纳米棒的生长时间不同使其荧光强度不同,TiO_2/Zn O纳米棒的荧光强度与单层TiO_2纳米棒相比有着微小的减弱,没有明显的衍射峰; TiO_2/ZnO纳米棒复合材料比单层TiO_2的光吸收强度高,提高其光学性能,但是吸光区域都在紫外光区域;在标准模拟太阳光照射下,TiO_2/Zn O纳米棒的光电流为0. 002 m A,单层TiO_2纳米棒的光电流为0. 006 m A,复合薄膜的电流有着明显的变化。     

Ag_3PO_4/ZnO纳米线阵列复合光催化剂的研制及光催化降解罗丹明B研究

水热法制备了ZnO纳米线阵列后,用逐级化学浴沉积法将Ag3PO4沉积在阵列上形成Ag3PO4/ZnO纳米线阵列复合光催化剂。运用XRD、SEM、EDS、紫外-可见漫反射光谱、光电流性能测试、光催化降解等技术手段对Ag3PO4/ZnO纳米线阵列的形貌结构、光电性能等进行表征。探讨了逐级化学浴沉积Ag3PO4的次数对其光催化效率的影响。光电性能测试表明,Ag3PO4/ZnO纳米线阵列具有比纯ZnO纳米线阵列更高的光生电流密度,光响应更好。与纯ZnO纳米线阵列相比,Ag3PO4/ZnO纳米线阵列材料对罗丹明B的光降解效率显著提高,降解速度是纯ZnO纳米线阵列的7.7倍,沉积5次的复合阵列的光催化活性最高。     

厚度对溶胶-凝胶法制备锂掺杂ZnO薄膜性能的影响

采用溶胶-凝胶旋涂法在玻璃衬底上制备了不同厚度的ZnO:Li半导体薄膜.采用X射线衍射仪和扫描电子显微镜分析了薄膜的物相结构和形貌,用Hall效应测量仪常温下测量薄膜的电学性能.结果表明:该薄膜具有高度的c轴择优取向性,所有薄膜只有1个(002)衍射峰,并且衍射强度随着膜厚增加而加强.ZnO:Li薄膜晶粒呈柱状,晶粒直径不随膜厚改变,约为40 um.ZnO:Li薄膜为P型导电,薄膜越厚,其电学性能与晶体结晶越好,(002)方向择优取向生长越明显.电阻率随着膜厚增加而减小,最小的电阻率为1.32×102(Ω·cm).载流子-空穴浓度为3.546×1016/cm3,迁移率为1.34cm2/(V·s).ZnO:Li薄膜在可见光范围内的透过率达到90%,薄膜对紫外光的吸收与厚度有关.     

亲水/水下超疏油的油水分离膜的制备及性能

近年来,膜技术在油水分离中的应用受到了研究者的广泛关注。将ZnO纳米线与氧化石墨烯(GO)片层掺混,利用真空抽滤手段,在聚偏氟乙烯支撑层上制备ZnO/GO薄膜。试验证明,ZnO纳米线在GO纳米片层间的穿插,改进了GO薄膜的内部结构和表面性质,使得薄膜的各项性能均得到改善和提升。ZnO/GO薄膜呈现出亲水和水下超疏油的性质,亲水角和水下亲油角分别为65°和175°;同时,提高膜渗透性能,纯水通量高达2 100 L/(m~2·h),为纯GO薄膜的32倍;在油水分离试验中,ZnO/GO薄膜表现出良好的油水分离性能和抗油污染性能,出水的油含量低于5 mg/L,膜通量恢复率高于80%;在分离实际含油废水时,ZnO/GO薄膜保持良好的抗污染性能和分离性能,通量衰减率为5 L/(m~2·h·min),通量恢复率为80%,分离效率约为92.8%。综上,ZnO/GO薄膜是一种新型高效的油水分离膜,在含油废水处理领域具有良好的研究和应用前景。     

金属—载体强相互作用（SMSI）对Pd／ZnO半导体陶瓷气敏特性的作用

本文借助XRD,红外光谱等分析手段,研究了金属-载体相互作用状态对Pd/ZnO半导体陶瓷气敏特性的影响,据此提出贵金属催化剂和半导体陶瓷在气敏特性中的共同作用机理。PdZn界面层是氢处理时半导体正离子和金属原子间的相互扩散及反应所致。可以认为金属-载体间的强相互作用(SMSI)能显著提高其气敏特性。     

氧化亚铜/氧化锌复合薄膜的制备及可见光催化研究

以导电玻璃(FTO)为基底,采用连续阴极电沉积方法在多孔结构的ZnO薄膜上合成具有单一(111)择优取向的Cu2O,制备了Cu2O/ZnO复合薄膜。采用X射线衍射和扫描电镜分别对薄膜的结构及形貌进行了表征。光吸收谱显示复合薄膜在可见光范围内具有较好的光吸收性能。可见光催化降解罗丹明B的实验表明,由于在两半导体接触界面上发生了电荷的转移,Cu2O/ZnO复合薄膜比单一的Cu2O薄膜具有更高的光催化活性,在2.5h内对罗丹明B的降解率可达到70%,而在相同条件下Cu2O薄膜的降解率仅为60%。     

ZnO纳米棒水热法生长与表征

采用两步法在FTO导电玻璃衬底上制备ZnO纳米棒,首先利用浸渍-提拉法在FTO导电玻璃衬底上制备ZnO晶种层,然后把有ZnO晶种层的FTO衬底放入盛有生长溶液的反应釜中利用水热法制备ZnO纳米棒.研究了生长溶液的浓度、生长温度和生长时间对所制备的对ZnO纳米棒阵列的微结构和光致发光性能的影响,利用X射线衍射(XRD)、扫描电子显微镜(SEM)和光致发光谱(PL)研究了ZnO样品的结构、形貌和光学性质.实验结果表明:所制备的ZnO纳米棒呈现六方纤锌矿结构,沿(002)晶面择优取向生长,纳米棒的平均直径约为100 nm,长度约为2.5 μm.所制备的ZnO纳米棒在390 nm附近具有很强的紫外发光峰和在550 nm附近有较弱的宽绿光发光峰.     

水热合成法制备ZnO纳米棒有序阵列薄膜

采用水热合成法在预先生长的ZnO种子层的玻璃衬底上制备出ZnO纳米棒有序阵列薄膜。通过X射线衍射、扫描电镜、透射电镜和选区电子衍射分析表明：所制备的薄膜由垂直于ZnO种子层的纳米棒组成,呈单晶六角纤锌矿ZnO结构,且沿[001]方向择优生长,纳米棒的平均直径和长度分别为10．0nm和3．3μm。     

不锈钢丝网上氧化锌纳米线阵列的 可控生长及光催化性能研究

利用水热法在不锈钢丝网上制备了氧化锌纳米线阵列,借助扫描电镜（SEM）对产物的形貌进行了表征,探讨了反应物浓度和反应时间对产物形貌的影响,并以橙黄Ⅱ为目标降解物,研究了不同生长条件下氧化锌纳米线阵列的光催化降解性能。研究结果表明：硝酸锌浓度和反应时间对氧化锌纳米线阵列的密度、长度、直径和晶形有重要影响,在硝酸锌浓度为0.1 mol/L、反应时间为6 h条件下,制得的氧化锌纳米线阵列具有较佳的光催化活性,多次循环实验结果表明其稳定性较高。另外,双层叠合的氧化锌纳米线的光催化降解性能优于单层氧化锌纳米线的实验结果,其不锈钢丝网的网状结构为制备多维纳米阵列和薄膜提供了一种新的研究思路。     

Electrochemical deposition of branched hierarchical ZnO nanowire arrays and its photoelectrochemical properties

Branched hierarchical ZnO nanowire arrays are synthesized on fluorine-doped tin oxide (FTO) substrate via a two-step electrochemical deposition process, which involves the electrodeposition of ZnO nanowire arrays on conductive glass substrate, followed by the electrochemical growth of ZnO nanorod branches on the backbones of the primary ZnO nanowires. The formation mechanism of the branched hierarchical nanostructure is discussed. It is demonstrated that coating the primary nanowire arrays with ZnO nanoparticles seed layer plays a key role in synthesising the branched hierarchical ZnO nanostructure. By adjusting the concentration of Zn(CH₃COO)₂ colloid in coating process and the reaction time of the second-step deposition, the density and the length of the secondary nanorod branches in the hierarchical nanostructures can be both varied. Moreover, the photoelectrochemical properties of the dye-sensitized solar cell (DSSC) based on branched hierarchical ZnO nanowire arrays are investigated. Due to the enlargement of the internal surface area within the branched nanostructure photoelectrode, the DSSC consisting of branched hierarchical ZnO nanowire arrays yields a power conversion efficiency of 0.88%, which is almost twice higher than that of the DSSC fabricated using bare ZnO nanowire arrays.     

Fabrication and characterization of hexagonally patterned quasi-1D ZnO nanowire arrays

Quasi-one-dimensional (quasi-1D) ZnO nanowire arrays with hexagonal pattern have been successfully synthesized via the vapor transport process without any metal catalyst. By utilizing polystyrene microsphere self-assembled monolayer, sol–gel-derived ZnO thin films were used as the periodic nucleation sites for the growth of ZnO nanowires. High-quality quasi-1D ZnO nanowires were grown from nucleation sites, and the original hexagonal periodicity is well-preserved. According to the experimental results, the vapor transport solid condensation mechanism was proposed, in which the sol–gel-derived ZnO film acting as a seed layer for nucleation. This simple method provides a favorable way to form quasi-1D ZnO nanostructures applicable to diverse fields such as two-dimensional photonic crystal, nanolaser, sensor arrays, and other optoelectronic devices.     

Angle-dependent photodegradation over ZnO nanowire arrays on flexible paper substrates

In this study, we grew zinc oxide (ZnO) nanowire arrays on paper substrates using a two-step growth strategy. In the first step, we formed single-crystalline ZnO nanoparticles of uniform size distribution (ca. 4 nm) as seeds for the hydrothermal growth of the ZnO nanowire arrays. After spin-coating of these seeds onto paper, we grew ZnO nanowire arrays conformally on these substrates. The crystal structure of a ZnO nanowire revealed that the nanowires were single-crystalline and had grown along the c axis. Further visualization through annular bright field scanning transmission electron microscopy revealed that the hydrothermally grown ZnO nanowires possessed Zn polarity. From photocatalytic activity measurements of the ZnO nanowire (NW) arrays on paper substrate, we extracted rate constants of 0.415, 0.244, 0.195, and 0.08 s^-1 for the degradation of methylene blue at incident angles of 0°, 30°, 60°, and 75°, respectively; that is, the photocatalytic activity of these ZnO nanowire arrays was related to the cosine of the incident angle of the UV light. Accordingly, these materials have promising applications in the design of sterilization systems and light-harvesting devices.     

Growth and characterization of ZnO/ZnTe core/shell nanowire arrays on transparent conducting oxide glass substrates

ABSTRACT: We report the growth and characterization of ZnO/ZnTe core/shell nanowire arrays on indium tin oxide. Coating of the ZnTe layer on well-aligned vertical ZnO nanowires has been demonstrated by scanning electron microscope, tunneling electron microscope, X-ray diffraction pattern, photoluminescence, and transmission studies. The ZnO/ZnTe core/shell nanowire arrays were then used as the active layer and carrier transport medium to fabricate a photovoltaic device. The enhanced photocurrent and faster response observed in ZnO/ZnTe, together with the quenching of the UV emission in the PL spectra, indicate that carrier separation in this structure plays an important role in determining their optical response. The results also indicate that core/shell structures can be made into useful photovoltaic devices.     

Low temperature growth of ZnO nanowire arrays with enhanced high performance photocatalytic activity and reusability

Aligned ZnO nanowire arrays have been grown on the silicon substrates with ZnO seed layer by an aqueous chemical growth process at low reaction temperature. The volumes of ammonium hydroxide solution are not only controlled by the dimension and density of ZnO nanowires, but are also influenced by their optical emission property. The ZnO nanowire arrays exhibit very strong and broad green emission from defect in the cathodoluminescence spectrum. In addition, the ZnO nanowires grown on the silicon substrates can serve as effective and convenient recyclable photocatalysts. Only a very slight decrease in the photodecomposition rate was observed after ten cycles of the photocatalysis experiment.     

Preparation of highly ordered ZnO nanowire arrays by paired-cell deposition

Highly ordered ZnO nanowire arrays were fabricated by paired cell method into nanoporous anodic alumina oxide (AAO) template. ZnO nanowires were uniformly assembled into the ordered channels of the AAO template. TEM and selected-area electron diffraction patterns indicated that the ZnO nanowires grow as a single crystal. The factors influencing the final filled density of ZnO nanowires, including the solution concentration and the diffusing temperature are discussed briefly. In addition, the possible mechanism is also proposed to account for the growth of the ZnO nanowires in the AAO template. This result has established that this paired cell method makes it possible to grow single-crystalline ZnO nanowires in the AAO template under appropriate conditions.     

Hydrothermal Growth and Application of ZnO Nanowire Films with ZnO and TiO2 Buffer Layers in Dye-Sensitized Solar Cells

This paper reports the effects of the seed layers prepared by spin-coating and dip-coating methods on the morphology and density of ZnO nanowire arrays, thus on the performance of ZnO nanowire-based dye-sensitized solar cells (DSSCs). The nanowire films with the thick ZnO buffer layer (~0.8–1 μm thick) can improve the open circuit voltage of the DSSCs through suppressing carrier recombination, however, and cause the decrease of dye loading absorbed on ZnO nanowires. In order to further investigate the effect of TiO₂ buffer layer on the performance of ZnO nanowire-based DSSCs, compared with the ZnO nanowire-based DSSCs without a compact TiO₂ buffer layer, the photovoltaic conversion efficiency and open circuit voltage of the ZnO DSSCs with the compact TiO₂ layer (~50 nm thick) were improved by 3.9–12.5 and 2.4–41.7%, respectively. This can be attributed to the introduction of the compact TiO₂ layer prepared by sputtering method, which effectively suppressed carrier recombination occurring across both the film–electrolyte interface and the substrate–electrolyte interface.     

Size-selected growth of transparent well-aligned ZnO nanowire arrays

This paper reports the effect of precursor concentration, growth temperature, and growth time on the size and density of ZnO nanowire arrays (ZNAs). The well-aligned ZNAs were grown on indium tin oxide substrate using a facile chemical bath deposition method. The results showed that the ZnO nanowires could be tailored to the desired sizes with a simple variation of the growth parameters. Optical transmission spectra revealed a sufficient transparency of the ZNAs, qualifying them for photovoltaic and other optoelectronic applications. An inverted hybrid solar cell was fabricated using the ZNAs as the electron collecting layer, and the solar cell exhibited a power conversion efficiency of 0.91%.     

Effects of Seed Layer Characteristics on the Synthesis of ZnO Nanowires

Single crystalline zinc oxide (ZnO) nanowires were synthesized on sputter-deposited ZnO seed layers via hydrothermal reactions in an equimolar (20 mM) aqueous solutions of Zn(NO₃)₂·6H₂O and C₆H₁₂N₄ at 90°C. The sputter-deposited ZnO seed layers were prepared to exhibit different crystalline structures in order to examine their effects on the growth of ZnO nanowires. It was found that the nanowire diameter depends on the size of the (002) grains of the seed layer. This is attributed to the epitaxially growth of the nanowires from the columnar grains of the seed layer which is shown by the TEM analysis.