In2O3敏化ZnO纳米棒阵列的性能及其光电催化活性

以掺氟SnO₂ (FTO)导电玻璃为基底, 采用水热法制备了ZnO纳米棒阵列. 通过In(NO₃)₃水溶液水洗的方法, 合成了In₂O₃敏化ZnO纳米棒阵列光催化剂. 采用场发射扫描电子显微镜(FESEM), X射线能谱(EDX), X射线衍射(XRD)及紫外-可见漫反射光谱(UV-Vis DRS)对样品的形貌、结构、组成、晶相等进行一系列的表征. 以罗丹明B (RhB)为目标降解物, 探究了In₂O₃敏化ZnO 纳米棒阵列光电催化活性. 采用场诱导表面光伏技术(FISPV)研究了不同含量的In₂O₃敏化ZnO纳米棒阵列在光照射下的光生电荷行为. 结合电化学工作站检测不同样品的光电流, 随着In₂O₃敏化量的改变, 光电流和开路电压也随之改变. 并探讨了In₂O₃敏化ZnO纳米棒阵列光生电荷行为与光电催化活性之间的关系. 结果表明, 适量In₂O₃敏化的ZnO光催化剂在可见光下2 h内对罗丹明B的降解效率达到95%, 是单纯ZnO纳米棒阵列的2.4倍.     

Assembly of Pt nanoparticles on electrospun In2O3 nanofibers for H2S detection

In this paper, we presented a simple and effective solution route to deposit Pt nanoparticles on electrospun In₂O₃ nanofibers for H₂S gas detection. The morphology and chemical structure of the as-prepared samples were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectra (XPS). The results showed that large quantities of In₂O₃ nanofibers with diameters about from 60 to 100 nm were obtained and the surface of them was decorated with Pt nanoparticles (5–10 nm in size). The In₂O₃ nanofibers decorated by Pt nanoparticles exhibited excellent gas sensing properties to H₂S, such as high sensitivity, good selectivity and fast response at relatively low temperature.     

Conductivity of SnO<Subscript>2</Subscript>-In<Subscript>2</Subscript>O<Subscript>3</Subscript> nanocrystalline composite films

The conductivity of films consisting of a mixture of SnO₂ and In₂O₃ nanocrystals at 200–500°C was studied. Based on the experimental data, it was assumed that in films containing less than 20 wt % In₂O₃, the current flows along SnO₂ nanocrystals. A model of conductivity in these films is presented; it includes an electron transfer from In₂O₃ to SnO₂, which forms positively charged In₂O₃ nanocrystals that contact the negatively charged SnO₂ nanocrystals. In the presence of In₂O₃ nanocrystals, the activation energy of the electron transfer between SnO₂ nanocrystals decreased substantially because of a decrease in the barrier of electron transfer between SnO₂ crystals under the action of the negative charge. As a result, a percolation cluster of charged SnO₂ crystals formed. At high contents of In₂O₃ (over 20 wt %), the conductivity increased dramatically. The curve of the temperature dependence of conductivity changed because of the appearance of a percolation cluster of In₂O₃ nanocrystals, in which the current passed. The conductivity of a mixed film of this kind differed from that of the nanocrystalline film of pure In₂O₃.     

基于电纺丝法的In2O3/CdO复合材料的制备及甲醛气敏特性

用静电纺丝法制备了In(NO₃)₃/聚乙烯吡咯烷酮(PVP)纺丝前驱物, 然后分别在500、600、700℃时烧结得到三种In₂O₃ 纳米纤维. 通过X 射线衍射(XRD)仪、热重差热分析(TG/DTA)、场发射扫描式电子显微镜(FE-SEM)表征结果得知, 500℃时In₂O₃的晶相已经形成, 且粒径为最小, 约为24 nm, 纳米纤维呈介孔结构.将三种烧结温度的In₂O₃纤维制作成气敏元件, 测试对比了三种元件对甲醛气体的敏感特性, 结果表明, 500℃烧结得到的In₂O₃纳米纤维在工作温度为240℃时响应最好, 对浓度为10×10^-6 (体积分数, φ)甲醛的响应为7.用静电纺丝法合成了CdO 纳米颗粒, 通过XRD、SEM 表征得知CdO 呈粒径约为68 nm 的颗粒. 将In₂O₃和CdO以不同摩尔比(1:1, 10:1, 20:1)复合, 对比测试了纯In₂O₃及三种In₂O₃/CdO复合材料对应的气敏元件对甲醛的气敏特性, 测试结果表明当In₂O₃纳米纤维与CdO纳米颗粒以摩尔比10:1 复合时, 元件的工作温度较低(200℃), 且对甲醛表现出最佳的气敏特性, 对浓度为10×10^-6甲醛的响应为13.6, 响应/恢复时间为140 s/32s. 最后对不同摩尔比复合的In₂O₃/CdO对甲醛的气敏机理进行了初步分析.     

In2O3/ZnO heterostructured nanotubes: electrospinning fabrication,characterization, and highly enhanced photocatalytic properties

In₂O₃/ZnO heterostructured nanotubes with cubic In₂O₃ and hexagonal ZnO were successfully synthesized via the combination of electrospinning and calcination process. The as-prepared materials are investigated by using thermogravimetric and differential scanning calorimetry, fourier transform infrared spectroscope, X-ray diffraction, scanning electron microscope and high-resolution transmission electron microscope techniques. The formation mechanism of In₂O₃/ZnO heterostructured nanotubes based on the kinetics of phase separation which results from the decomposition of polyvinyl pyrrolidone during the calcination process is also discussed in detail. The photocatalytic degradation tests reveal that In₂O₃/ZnO heterostructured nanotubes exhibit the highly improved photocatalytic properties compared with the single-component ZnO and In₂O₃ materials.     

Sensor properties of the nanostructured In2O3-CeO2 system in detection of reducing gases

The sensor properties of nanostructured In₂O₃-CeO₂ composite films with different compositions in hydrogen and carbon monoxide detection in air in the temperature range 280–500°C were studied. The temperature curves of the sensor effect S have a shape typical for metal oxide sensors with maxima S _max at definite temperatures Tmax. The maxima characterize the sensor properties of the films and increased considerably when small amounts of CeO₂ were added to In₂O₃. The highest sensitivity was found in composite films with 3–10 wt % CeO₂. When the composite was further enriched with ceric oxide, the sensitivity decreased; at 40 wt % CeO₂ it was considerably lower than that of pure In₂O₃. The introduction of CeO₂ in In₂O₃ also caused a shift of Tmax toward lower temperatures. The mechanism of the sensitivity of the In₂O₃-CeO₂ composite was considered; it includes the promotion of sensor reactions by small CeO₂ nanoclusters lying on the surface of In₂O₃ crystals and an electron transfer from In₂O₃ to CeO₂.     

Structural aspects and defect chemistry in In2O3

The C-type rare earth structure of In₂O₃ is compared with the fluorite structure. The stability of the structure is discussed based on DTA and X-ray work and electron microscopy. Ordering of defects does not take place, so that defect chemistry can be formulated for isolated defects in nonstoichiometric In₂O₃. The influence of the incorporation of aliovalent cations into the In₂O₃ host lattice is discussed and a defect model is suggested.     

氧化铟八面体、纳米带、锯齿状纳米线和纳米链的可控合成

在N₂/H₂O混合气流中将硅片上金覆盖的金属铟颗粒加热到800 ℃制备出了不同形貌的In₂O₃纳米结构, 在距铟源不同距离处依次得到In₂O₃的八面体、纳米带、锯齿状纳米线和纳米链. 采用拉曼光谱、扫描电镜、X射线衍射和透射电镜对产物进行了表征分析. 结果表明, 八面体、纳米带、锯齿状纳米线和纳米链均为立方相单晶结构的In₂O₃. 基于气-固和气-液-固生长机理详细分析了八面体、纳米带、锯齿状纳米线和纳米链的生长过程, 提出了不同形貌In₂O₃纳米结构的生长模式.     

Mechanism of the conductivity and sensor response of nanostructured In2O3+ZnO films

The conductivity and sensor properties of mixed nanostructured In₂O₃+ZnO metal oxide systems with different component ratios are investigated. It is found that maximum sensor sensitivity in detecting hydrogen and CO in composite films containing 15 and 80 wt % In₂O₃ considerably exceeds the sensitivity of individual oxides. A mechanism of the sensor action, which is largely determined by the dependency of the paths of conductivity in a composite metal-oxide film on its composition, is proposed. It is established that the main factors determining the conductivity and sensor sensitivity of In₂O₃ + ZnO composite are modifications in the electron structure of crystals (mainly by In₂O₃) during the formation of composites, electron transfer from In₂O₃ to ZnO, and the catalytic activity of ZnO. It is shown in particular that ZnO effectively catalyzes the reaction of hydrogen dissociation and, in contact with In₂O₃, favors the chemical sensibilization of the sensor response of such mixed metal oxide systems in detecting H₂ and CO.     

Reduced graphene oxide-porous In2O3 nanocubes hybrid nanocomposites for room-temperature NH3 sensing

Metal oxide semiconductors (MOS)-reduced graphene oxide (rGO) nanocomposites have attracted great attention for room-temperature gas sensing applications. The development of novel sensing materials is the key issue for the effective detection of ammoniagas at room temperature. In the present work, the novel reduced graphene oxide (rGO)-In₂O₃ nanocubes hybrid materials have been prepared via a simple electrostatic self-assembly strategy. Characterization results exhibit that the intimate interfacial contact between In₂O₃ nanocubes and the rGO sheets are achieved. Particularly, the as-prepared rGO/In₂O₃ nanocomposites displayed high sensitivity, fast response and excellent selectivity towards ammonia (NH₃) at room-temperature, which clearly uncovers the merit of structural design and rational integration with rGO sheets. The superior gas sensing performance of the rGO/In₂O₃ nanocomposites can be attributed to the synergetic effects of rGO sheets and porous In₂O₃ nanocubes. The reported synthesis offers a general approach to rGO/MOS-based semiconductor composites for room-temperature gas sensing applications.     

Preparation of novel visible-light-driven In<Subscript>2</Subscript>O<Subscript>3</Subscript>–CaIn<Subscript>2</Subscript>O<Subscript>4</Subscript> composite photocatalyst by sol–gel method

Novel visible-light-activated In₂O₃–CaIn₂O₄ photocatalysts were developed in this paper through a sol–gel method. The photocatalytic activities of In₂O₃–CaIn₂O₄ composite photocatalysts were investigated based on the decomposition of methyl orange under visible light irradiation (λ > 400 nm). The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrum (EDS), X-ray photoelectron spectroscopy (XPS) and UV–vis diffused reflectance spectroscopy (DRS). The results revealed that the In₂O₃–CaIn₂O₄ composite samples with different In₂O₃ and CaIn₂O₄ content can be obtained by controlling the synthesis temperature, and the composite photocatalysts extended the light absorption spectrum toward the visible region. The photocatalytic tests indicated that the composite samples demonstrated high visible-light activity for decomposition of methyl orange. The significant enhancement in the In₂O₃–CaIn₂O₄ photo-activity under visible light irradiation can be ascribed to the efficient separation of photo-generated carriers in the In₂O₃ and CaIn₂O₄ coupling semiconductors.     

ZnO/In2O3复合空心球的制备及其光电催化葡萄糖降解性能

通过葡萄糖协助的水热以及随后的退火处理两步法成功制备了系列ZnO/In₂O₃复合空心球. X射线衍射谱(XRD)表明, 经500 ℃退火制得的ZnO/In₂O₃复合空心球中ZnO以非晶态存在, 但是随着退火温度的提高, 其逐渐转变为纤锌矿结构. 场发射扫描电子显微镜(FE-SEM)和透射显微镜(TEM)结果表明, ZnO/In₂O₃复合材料具有空心球结构, 复合纳米颗粒之间结合紧密. 将ZnO/In₂O₃复合空心球组装成薄膜光电极, 研究了其光电催化降解葡萄糖的性能. 结果表明, 700 ℃退火处理的ZnO/In₂O₃复合空心球薄膜电极可产生最高的光致电流密度. 通过光致发光光谱(PL)发现, 与ZnO或In₂O₃空心球相比, ZnO/In₂O₃复合空心球的发光强度猝灭效果明显. 这是由于复合材料中晶界处产生的p-n结电场, 降低了光生电子-空穴对的复合几率, 从而使更多的光生电子可迁移到电极表面.     

Graphene oxides as support for the synthesis of nickel sulfide–indium oxide nanocomposites for photocatalytic,antibacterial and antioxidant performances

NiS (nickel sulfide)–In₂O₃ (indium oxide) nanostructures and NiS–In₂O₃ decorated on graphene oxide (GO) were demonstrated by ultrasonic/hydrothermal method. The structural study demonstrates the preparation of bixbyite and hexagonal phase of In₂O₃ and NiS for all of the synthesized catalysts. The band gap of the synthesized catalyst was determined to be in the range of 2.30–3.00 eV. A morphological evaluation by field emission scanning electron microscopy of NiS–In₂O₃ decorated on graphene oxide shows support for the NiS–In₂O₃ on the graphene oxide layer. Different test parameters were performed to study the phase and morphology. The particle sizes of the In₂O₃, NiS–In₂O₃ and NiS–In₂O₃/GO nanocomposites were 56.0, 62.0 and 66.0 nm, respectively. The photocatalytic performance of NiS–In₂O₃/GO nanocomposites was examined for the degradation of methylene blue dye under a UV lamp. The prepared sample shows 98.25% photocatalytic degradation within 40 min and at pH 9. With the presence the NiS and GO, the photo-degradation capacities of In₂O₃ and NiS–In₂O₃ are improved owing to the low band gap being calculated in UV–vis DRS analysis. The high ratio of NiS causes the highest photocatalytic properties of NiS–In₂O₃ nanocomposites owing to the enhancement of charge separation efficiency and generation of hydroxyl radicals. This study presents a facile and low-cost method to prepare highly active NiS–In₂O₃/GO nanocomposites. The antibacterial data indicate the significant properties of NiS–In₂O₃/GO nanocomposites for this study.     

Rationally Designed Double-Shell Dodecahedral Microreactors with Efficient Photoelectron Transfer: N-Doped-C-Encapsulated Ultrafine In2O3 Nanoparticles

It is desirable but challenging to design efficient micro-/nanoreactors for chemical reactions. In this study, we have fabricated mesoporous double-shelled hollow microreactors composed of N-doped-C-coated ultrafine In₂O₃ nanoparticles [N-C/In₂O₃ HD (hollow dodecahedron)] by the thermolysis of a dodecahedral In-based framework in Ar atmosphere. The obtained N-C/In₂O₃ HD exhibited excellent activity in the photocatalytic oxidative hydroxylation of a series of arylboronic acid substrates. This property can be attributed to its enhanced optical absorption and efficient separation of photo-generated electron–hole pairs, imparted by the unique structure and uniformly coated N-doped C layers. Furthermore, we found O₂^.− to be the critical active species in the process of photocatalytic oxidative hydroxylation of arylboronic acids, and the formation mechanism of this radical is also proposed. Theoretical calculations further confirmed that the N-doped C layer serves as an electron acceptor and revealed the microscopic charge-carrier migration path through the In₂O₃/N-doped graphite interfaces. Thus, photo-generated electrons from hybrid states of In₂O₃, composed of In 5s and 2p orbitals, are transferred into the hybrid states of N-doped graphite, composed of C 2p and N 2p orbitals. The present study may be helpful for understanding and designing carbon-based micro-/nanoreactors for photocatalytic reactions, and may also be useful for investigating related micro-/nanoreactors.     

Preparation of size‐controlled In2O3 nanoparticles

Highly crystalline and monodisperse In₂O₃ nanoparticles were successfully prepared by thermal decomposition of In(dipy)₃Cl₃·2H₂O in oleylamine and oleic acid under inert atmosphere. The size of In₂O₃ nanoparticles could be readily tuned from 10–15 nm to 40–50 nm, depending on the molar ratio of precursor to combined solvent in the reaction system. As‐synthesized In₂O₃ nanoparticles have a center‐body cubic structure as characterized by powder X‐ray diffraction and selected‐area electron diffraction. Transmission electron microscopy images showed that In₂O₃ nanoparticles have a narrow size distribution. A relatively strongly PL peak centered at 378 nm could be clearly seen when 10–15 nm In₂O₃ nanoparticles redispersed in cyclohexane were excited at 275 nm at room temperature. Copyright © 2007 John Wiley & Sons, Ltd.     

Deposition of In2O3 nanofibers on polyimide substrates to construct high-performance and flexible trimethylamine sensor

Flexible trimethylamine sensor has been realized based on In₂O₃ nanofibers via electrospinning and a deposition technique. The web-like In₂O₃ nanofibers with high length-to-diameter ratios are benefit for gas adsorption and desorption. High trimethylamine sensing properties are observed. The sensors can detect trimethylamine gas down to 1 ppm at 80 °C with the response up to 3.8. Additionally, rapid response (6 s) and recovery (10 s) behavior can also be obtained. Good reliability and flexibility are observed in 100 bending/extending cycles. Our results open a new route to construct flexible gas sensors in practice.     

Sensors based on SnO<Subscript>2</Subscript> + In<Subscript>2</Subscript>O<Subscript>3</Subscript> composite films for detecting CO in air

The sensor properties of nanostructured films of SnO₂, In₂O₃, and their combinations for detecting CO in air in the temperature range of 330–520°C were investigated. It was found that SnO₂ films show the least sensitivity to CO. Sensitivity grows as the concentration of In₂O₃ in SnO₂ increases, and it reaches its maximum value in pure In₂O₃. At the same time, the maximum of sensitivity to CO in air shifts towards low temperatures. Sensor response time was found to be about 1 s for the studied SnO₂ and In₂O₃ films, and about 0.5 s for the composite film. The mechanism of sensor sensitivity for the studied metal oxide films in detecting CO in air is discussed.     

Efficient Decomposition of Organic Pollutants Over In2O3/TiO2 Nanocomposite Photocatalyst Under Visible Light Irradiation

The heterojunction structures of In₂O₃/TiO₂, exhibiting visible light photocatalytic efficiency, has been synthesized by utilizing maleic acid as an organic linker to combine In₂O₃ and Degussa P25 (TiO₂) nanoparticles. The prepared nanocomposite has been characterized by FESEM, TEM, XRD and UV?CVisible reflectance spectra. The photocatalytic efficiency of the composite photocatalyst has been investigated based on the decomposition of 2-propanol (IP) in gas phase and 1,4-dichlorobenzene (DCB) in aqueous phase under visible light (??????420?nm) irradiation. The results reveal that the In₂O₃/TiO₂ composite photocatalyst with 7?wt% In₂O₃ demonstrated 6.3 times of efficiency in evolving CO₂ from gaseous IP and 8.7 times of efficiency in removing aqueous DCB in compare with Degussa P25. In this In₂O₃/TiO₂ composite system, TiO₂ seems to be the principal photocatalyst whereas the function of In₂O₃ is to sensitize TiO₂ by absorbing visible light (??????420?nm). The extraordinary high photocatalytic efficiency of this composite In₂O₃/TiO₂ under visible light has been explained on the basis of relative energy band positions of the component semiconductors.     

Chemical‐Bath‐Deposited Indium Oxide Microcubes for Solar Water Splitting

We fabricated films of cubic indium oxide (In₂O₃) by chemical bath deposition (CBD) for solar water splitting. The fabricated films were characterized by X‐ray diffraction analysis, Raman scattering, X‐ray photoelectron spectroscopy, and scanning electron microscopy, and the three‐dimensional microstructure of the In₂O₃ cubes was elucidated. The CBD deposition time was varied, to study its effect on the growth of the In₂O₃ microcubes. The optimal deposition time was determined to be 24 h, and the corresponding film exhibited a photocurrent density of 0.55 mA cm^?2. Finally, the film stability was tested by illuminating the films with light from an AM 1.5 filter with an intensity of 100 mW cm^?2.     

Multi-component catalysts with spinel structure for the selective reduction of nitrogen oxide by ethylene in lean-exhaust gas streams

The Ga₂O₃-Al₂O₃-ZnO (GAZ) multi-component spinel powders with incorporated Cu²⁺, Co²⁺, Fe²⁺, Ni²⁺, Mn²⁺ and In²⁺ metal cations were synthesized by co-precipitation method from a mixed solution of nitrate salts. Spinel crystal structure of each composition was confirmed by XRD measurements. The multi-component oxide powders were tested in the reduction of nitrogen oxide (NO) under lean conditions. Among the catalysts tested, In₂O₃-containing GAZ with a pure spinel phase structure showed promising catalytic activity in the NO reduction in the presence of 10% H₂O vapor. In addition, the effect of H₂O vapor and SO₂ on the selective reduction of NO over In₂O₃-GAZ/cordierite and In₂O₃-GAZ/metal honeycombs catalysts has been investigated.