无真空、低成本Mist-CVD外延制备高质量单晶NiO/Ga2O3 p-n异质结与器件(英文)

在氧化镓(Ga₂O₃)材料p型掺杂困难的背景下,Ga₂O₃ p-n异质结器件在氧化镓器件的应用中起着重要作用.因此,寻找一种高效、经济的制备方法制备Ga₂O₃异质结对器件应用具有重要意义.在这项工作中,我们成功基于低成本、无真空的雾化学气相沉积(Mist-CVD)外延制备了单晶氧化镍(NiO)和β-Ga₂O₃异质结.其中,NiO(111)和β-Ga₂O₃(-201)的XRD摇摆曲线半高宽分别为0.077°和0.807°.NiO与β-Ga₂O₃之间的能带表现为Ⅱ型异质结构.基于此异质结,我们制备了准垂直器件,器件具有明显的p-n结整流特性,反向击穿电压为117 V.本工作为β-Ga₂O₃异质p-n结的制备提供了一种低成本、高质量的方法.     

CuMnO2/TiO2复合光催化剂增效催化降解亚甲基蓝

首次利用旋涂法将CuMnO_2纳米晶负载于TiO_2纳米棒阵列薄膜上,制备出光催化性能增强的CuMnO_2/TiO_2复合光催化剂,并考察了样品对亚甲基蓝(MB)的光催化降解性能。研究结果表明,CuMnO_2纳米晶和TiO_2纳米棒之间形成p-n异质结结构,能够有效促进电子和空穴的分离,使得CuMnO_2/TiO_2复合光催化剂具有更高的光催化性能。采用浓度为0.25 g/L的CuMnO_2悬浮液制得的CuMnO_2/TiO_2复合材料的光催化降解效率最高,其光催化效率和表观速率分别为88%和0.298 6 h~(-1),较纯TiO_2提高约26%和80%。     

纳米棒状Ag3PO4/TiO2异质结复合材料的可见光催化性能

采用水热法制备了一维棒状TiO_2纳米材料,再通过原位生长法合成了棒状纳米Ag_3PO_4/TiO_2复合材料,制备了不同摩尔量的纳米棒状Ag_3PO_4/TiO_2异质结复合材料。通过X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、X射线光电子能谱仪(XPS)、漫反射紫外-可见近红外光谱仪(UV-Vis-DRS)和电化学阻抗谱(EIS)对纳米棒状Ag_3PO_4/TiO_2异质结复合材料的晶体结构、形貌、光吸收特性和电子复合情况等进行了表征,并在可见光照射下研究了甲基橙和苯酚的光降解率。结果表明:制备的纳米棒状TiO_2具有更大的比表面积,为纳米Ag_3PO_4的负载提供更多的活性位点,提高了光利用效率;Ag_3PO_4/TiO_2复合材料有异质结的形成,其内建电场可有效提高电子-空穴对的分离效率,进而提高材料的光催化性能和稳定性。     

NiO/In2O3纳米复合材料的制备及气敏性能研究

采用水热法结合水浴法制备出了NiO/In2O3纳米复合材料,利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线衍射仪(XRD)等对其微观形貌和晶相进行表征分析。表征结果表明,制备所得In2O3纳米微球直径为200~300 nm,其表面均匀包覆厚度约为20 nm的NiO纳米片。气敏测试结果表明,基于NiO/In2O3异质结纳米复合材料的气体传感器对甲醛的最佳工作温度为220℃;在最佳工作温度下,对浓度为1×10^-5的甲醛气体响应可达到20,响应/恢复时间分别为4 s/16 s,且具有较好的重复性和选择性。最后,对分级结构及p-n异质结对其气敏机理进行了探讨。     

聚苯胺太阳电池的研究

本文利用聚苯胺和聚苯胺复合材料与n型硅制备了有机p-n异质结太阳电池,对电池的伏安特性、开路电压、短路电流和稳定性进行了表征和分析,对电池的机理进行了探讨,分析了影响聚苯胺p-n异质结电池特性的各种因素,得到了一些很有意义的结果.     

TiO_2/MoS_2复合材料的制备及其在光催化和储能电池中的应用研究进展

TiO_2与MoS_2具有良好的物理和化学性质,但它们在很多领域的应用仍受到自身缺陷的限制。而TiO_2与MoS_2复合后形成的异质结可有效克服两种材料的缺陷、有效提高复合材料的光电属性,进一步提高复合材料作为光催化剂和电极材料的应用性能。综述了包覆型和负载型TiO_2/MoS_2复合材料的制备及其在光催化和储能电池方面的最新研究进展,并对复合材料的应用进行了展望。     

不同形貌TiO_2基异质结构纳米材料构建及应用研究进展

综述了不同形貌二氧化钛(TiO_2)基异质结纳米材料的构建,如TiO_2纳米带、纳米棒、纳米纤维、纳米管和空心球与金属氧化物、金属硫化物和多元化合物异质结,以及TiO_2基异质结纳米材料在光催化和电化学应用的最新研究进展。     

镍基复合催化剂的制备及其在生物质气化气体净化中的应用

采用共沉淀法制备了NiO/TiO_2复合催化剂,通过XRD、XPS和SEM等手段对催化剂的物质组成及形貌进行了表征。结果表明,NiO/TiO_2复合催化剂中含有锐钛矿型TiO_2和NiO两相,形貌为纳米花球,微球的大小在1μm左右;NiO以纳米颗粒的形式附着在TiO_2纳米花表面,这种结构有利于NiO/TiO_2复合催化剂比表面积的增大,以及催化活性的增强。以城市垃圾为生物质原料,NiO/TiO_2复合催化剂和ICI46-1型催化剂为催化剂,进行了催化生物质气化实验,比较了两种催化剂的催化活性和使用寿命。结果表明,NiO/TiO_2复合催化剂的催化活性明显优于ICI46-1型催化剂。当NiO/TiO_2复合催化剂的使用寿命为300 min时,城市生活垃圾气化的燃气产率为1.70 m~3/kg(MSW),而燃气中的焦油含量仅0.27 g/m~3,催化剂活性仍保持在98%以上。     

陶瓷/聚合物复合材料的电性能及应用

介绍了多种陶瓷/聚合物复合材料在压电、介电、热释电等方面的电学性能及它们的开发应用概况, 并对一种崭新的陶瓷/聚合物复合材料——n 型SrTiO₃半导体陶瓷/p 型半导体聚苯胺,复合形成p-n 异质结的方法过程、电学性能及潜在应用进行了评述。      

NiO/ZnO薄膜太阳能电池的研究进展

综述了近年来国内外NiO/ZnO薄膜太阳能电池的研究进展,重点介绍了有无掺杂的NiO/ZnO薄膜太阳能电池的制备方法及电性能指标,并简要分析了该异质结薄膜太阳能电池存在的问题和未来发展动向,认为未来NiO/ZnO薄膜太阳能电池的研究应集中在通过选择掺杂元素以及引入中间层来提高电学特性.     

Enhancement of photocatalytic properties of TiO2 nanobelts through surface-coarsening and surface nanoheterostructure construction

In this work, heterostructures were obtained by uniformly assembling NiO nanoparticles on the surface-coarsened TiO₂ nanobelts through a precipitation process. The uniform assembling of NiO nanoparticles led to a large number of nano-p-n-junction heterostructures on the surface of the TiO₂ nanobelts, where NiO and TiO₂ are p- and n-type semiconductors, respectively. Compared with both pure NiO nanoparticles and TiO₂ nanobelts, NiO nanoparticles/TiO₂ surface-coarsened nanobelt heterostructured composite exhibited a greatly enhanced photocatalytic activity in the decomposition of a model dye compound methyl orange under ultraviolet light irradiation. It was argued that the nano-p-n-junctions effectively reduce the recombination of electrons and holes, thus resulting in enhanced photocatalytic property of the heterostructured composites. The better performance of the surface-coarsened nanobelts is due to the increased photo absorption and production of charge carriers, which renders the composites with further enhanced photocatalytic performance. The established approach allows the control of the nano-p-n junction heterostructure on the nanobelts, and hence, their photocatalytic effect.     

Enhanced Photocatalytic Performances of CeO2/TiO2 Nanobelt Heterostructures

CeO₂/TiO₂ nanobelt heterostructures are synthesized via a cost‐effective hydrothermal method. The as‐prepared nanocomposites consist of CeO₂ nanoparticles assembled on the rough surface of TiO₂ nanobelts. In comparison with P25 TiO₂ colloids, surface‐coarsened TiO₂ nanobelts, and CeO₂ nanoparticles, the CeO₂/TiO₂ nanobelt heterostructures exhibit a markedly enhanced photocatalytic activity in the degradation of organic pollutants such as methyl orange (MO) under either UV or visible light irradiation. The enhanced photocatalytic performance is attributed to a novel capture–photodegradation–release mechanism. During the photocatalytic process, MO molecules are captured by CeO₂ nanoparticles, degraded by photogenerated free radicals, and then released to the solution. With its high degradation efficiency, broad active light wavelength, and good stability, the CeO₂/TiO₂ nanobelt heterostructures represent a new effective photocatalyst that is low‐cost, recyclable, and will have wide application in photodegradation of various organic pollutants. The new capture–photodegradation–release mechanism for improved photocatalysis properties is of importance in the rational design and synthesis of new photocatalysts.     

Thermal properties of PS/TiO2 nanocomposites obtained by in situ bulk radical polymerization of styrene

TiO₂ nanoparticles, surface modified with 6-palmitate ascorbic acid, were incorporated in polystyrene (PS) by in situ bulk radical polymerization of styrene using 2,2′-azobisisobutyronitrile as initiator. The molar mass and polydispersity of synthesized samples were estimated by gel permeation chromatography. The influence of surface modified TiO₂ nanoparticles on the thermal properties of PS matrix was examined using thermogravimetry and differential scanning calorimetry. Molar mass and polydispersity of PS were not influenced by the presence of the TiO₂ nanoparticles. On the other hand, PS/TiO₂ nanocomposites have higher glass transition temperature and better thermal and thermooxidative stability than the pure PS.     

Statistical analysis of particle dispersion in a PE/TiO2 nanocomposite film

The dispersion of TiO₂ in polypropylene (PE) film has been characterised by a selection of microscopic methods – scanning electron microscopy (SEM), focussed ion beam (FIB) and secondary ion mass spectrometry (SIMS). Using a combination of microscopy and mathematic tools, the TiO₂ dispersion in different nanocomposites can be compared quantitatively, even for nanocomposites with different TiO₂ loadings, which gives insight into the relationship between particle dispersion and properties.     

Enhanced Photocatalytic Property of Reduced Graphene Oxide/TiO2 Nanobelt Surface Heterostructures Constructed by an In Situ Photochemical Reduction Method

A facile method is proposed to assemble graphene oxide (GO) on the surface of a TiO₂ nanobelt followed by an in situ photocatalytic reduction to form reduced graphene oxide (rGO)/TiO₂ nanobelt surface heterostructures. The special colloidal properties of GO and TiO₂ nanobelt are exploited as well as the photocatalytic properties of TiO₂. Using water–ethanol solvent mixtures, GO nanosheets are tightly wrapped around the surface of the TiO₂ nanobelts through an aggregation process and are then reduced in situ under UV‐light irradiation to form rGO/TiO₂ nanobelt surface heterostructures. The heterostructures enhance the separation of the photoinduced carriers, which results in a higher photocurrent due to the special electronic characteristics of rGO. Compared to TiO₂ nanobelts, the rGO/TiO₂ nanobelt surface heterostructures possess higher photocatalytic activity for the degradation of methyl orange and for the production of hydrogen from water, as well as excellent recyclability, with no loss of activity over five cycles.     

Solid state dye-sensitized solar cell with TiO2/NiO heterojunction: Effect of particle size and layer thickness on photovoltaic performance

The present work demonstrates the usefulness of nickel oxide as a hole transporting material in solid state dye-sensitized solar cells (SSDSSCs). We report on the photovoltaic performances of sensitized TiO₂/NiO heterojunctions, and demonstrate that the TiO₂ film thickness and morphology, as well as NiO film thickness, have significant effects on the photovoltaic behaviour of TiO₂/NiO SSDSSC. Under 1 sun AM1.5G simulated illumination, the SSDSSCs demonstrated best photovoltaic performance with a short circuit photocurrent density, open circuit voltage, fill factor and efficiency of 0.91 mA cm⁻², 780 mV, 40% and 0.3%, respectively. This study draws attention to the feasibility of enhancing the photovoltaic performance in SSDSSC devices through development of appropriately designed sensitized TiO₂/NiO heterojunctions.     

Synthesis and characterization of TiO<Subscript>2</Subscript>–NiO and TiO<Subscript>2</Subscript>–WO<Subscript>3</Subscript> nanocomposites

TiO₂–NiO and TiO₂–WO₃ nanocomposites were prepared by hydrothermal and surface modification methods. The samples were analyzed using X-ray diffraction, Scanning Electron Microscope images, Transmission Electron Microscope, Energy dispersive analysis, Zeta potential, Electrophoretic mobility and Photocatalysis activity measurement. XRD data sets of TiO₂–NiO, TiO₂–WO₃ powder nanocomposite have been studied for the inclusion of NiO, WO₃ on the anatase-rutile mixture phase of TiO₂ by Rietveld refinement. The cell parameters, phase fraction, the average grain size, strain and bond lengths between atoms of individual phases have been reported in the present work. Shifted positional co-ordinates of individual atoms in each phase have also been observed.     

Probing the compositional, structural and morphological aspects of CdSe-TiO2 nanocomposites by surface-sensitive techniques

In this work, a colloidal suspension of trioctyl phosphine oxide/trioctyl phosphine (TOPO/TOP)-capped CdSe QD's of size ∼5 nm was prepared by chemical route and these QD's were anchored on the surface of sol-gel prepared nanoporous TiO₂ layers in THF-ethanol solvent either by direct adsorption or with the aid of bi-functional linker molecule mercaptoacetic acid (MPA). The particle size estimation of both TiO₂ and CdSe nanoparticles by X-ray diffraction (XRD) and transmission electron microscopic (TEM) measurements concur well with each other. Energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) studies elucidate the signatures of TiO₂, CdSe nanoparticles and linker which is also supported by the presence of contrasting images in TEM studies respectively. XPS depth-profiling measurements have been used as a probe to determine the chemical composition and structure of CdSe nanocrystals and CdSe-TiO₂ nanocomposites respectively. The CdSe nanoparticles and CdSe-TiO₂ nanocomposites formed by different routes are modeled, based on the observations of several complimentary techniques.     

Semiconductor characterization of Cr-doped titania electrodes with p-n homojunction devices

A nano-TiO₂ electrode with a p-n homojunction device was designed and fabricated by coating of the nano-TiO₂ (n-type) film together with the Cr³⁺-doped TiO₂ (p-type) film. The sample films were prepared with synthesized sol-gel TiO₂ which were verified as nano-size particles with anatase structure. The semiconductor characteristic of the p-type and n-type films was analyzed by current-voltage (I-V) measurements. Results show that the rectifying characteristic of the TiO₂ films was observed from the I-V data illustration for both the n-type and p-type films. In addition, the characteristic of the rectifying curves was influenced by the fabrication conditions of the sample films, such as the doping concentration of Cr³⁺, heating temperature of the films, and film thickness. From the I-V analysis, the rectifying current of this diode showed a 10² mA order higher than the one of the n-type film. The p-n homojunction TiO₂ electrode showed greater performance of electronic properties than the n-type TiO₂ electrode.     

Preparation of graphene/TiO2 anode materials for lithium-ion batteries by a novel precipitation method

This paper reports a large-scale production route for graphene/TiO₂ nanocomposites using water-based in situ precipitation method. In this method, freshly prepared graphene oxides/TiO₂ obtained by precipitating Ti(SO₄)₂ with NH₃H₂O was subjected to heat treatment in the presence of N₂, which resulted in the formation of graphene/TiO₂ nanocomposites. Graphene/TiO₂ composites prepared by our method were found to be suitable as anode materials for lithium ion batteries because of its stable cycling performance and high capacity.