Preparation and characterization of In2O3/ZnO heterostructured microbelts by sol–gel combined with electrospinning method

Long and thin In₂O₃/ZnO heterostructured microbelts were synthesized by sol–gel combined with electrospinning process. The as-prepared microbelts show the well defined one-dimensional belt structures with 1–5 μm in width and tens of millimeters in length. The polycrystalline microbelts calcined at 973 K for 1 h are still continuous and have the uniform rectangular cross sections and the thickness to width ratio is around 1:10. The crystalline phases of samples are investigated by X-ray diffraction and the morphology is examined using transmission electron microscope and scanning electron microscope. In₂O₃/ZnO heterostructured microbelts exhibit the excellent visible photocatalytic property in the photodegradation of methyl orange (MO), and over 94 % of MO was degraded within 3 h.     

Enhanced photocatalytic activities of ZnO thin films: a comparative study of hybrid semiconductor nanomaterials

Nanostructure single ZnO, SnO₂, In₂O₃ and composite ZnO/SnO₂, ZnO/In₂O₃ and ZnO/SnO₂/In₂O₃ films were prepared using sol?Cgel method. The obtained composite films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV?CVis spectroscopy. The photocatalytic activities of composite films were investigated using phenol (P), 2,4-dichlorophenol (2,4-DCP), 4-chlorophenol (4-CP) and 4-aminophenol (4-AP) as a model organic compounds under UV light irradiation. Hybrid semiconductor thin films showed a higher photocatalytic activity than single component ZnO, SnO₂ and In₂O₃ films. The substituted phenols degrade faster than phenol. The ease of degradation of phenols is different for each catalyst and the order of catalytic efficiency is also different for each phenol. The use of multiple components offered a higher control of their properties by varying the composition of the materials and related parameters such as morphology and interface. It was also found that the photocatalytic degradation of phenolic compounds on the composite films and single films followed pseudo-first order kinetics.     

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.     

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.     

ZnO修饰提升花状BiOBr的可见光催化降解罗丹明B性能

以Bi(NO3)3·5H2O、Zn(CH3COO)2·2H2O和NaBr为前驱体,采用简单溶剂热法制备BiOBr/ZnO三维花状微纳米复合材料.采用X射线衍射、扫描电子显微镜、X射线光子能谱、N2吸附-脱附、光致发光和电子顺磁共振等分析技术对其理化性质进行了表征.通过可见光催化降解罗丹明B(RhB)的实验测试了复合材料...     

Synthesis,characterization, and biosensing application of ZnO/SnO2 heterostructured nanomaterials

In this work, zinc oxide/tin oxide (ZnO/SnO₂) heterostructured nanomaterials were synthesized by hydrothermal method. Transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction measurements revealed that the product was composed of ZnO nanowires and SnO₂ nanobranches. The novel ZnO/SnO₂ heterostructured nanocrystals were for the first time used as a supporting matrix to explore a novel immobilization and biosensing platform of redox proteins. UV–visible absorption investigation indicated that hemoglobin (Hb) intercalated well in the ZnO/SnO₂ heterostructured nanocrystals retained its native structure. Comparative experiments have confirmed that the ZnO/SnO₂-based biosensor not only had enhanced direct electron transfer capacity but also displayed excellent electrocatalytic properties such as higher sensitivity and wider linear range to the detection of hydrogen peroxide in comparison with the ZnO- and SnO₂-based biosensors.     

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.     

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.     

Synthesis,Characterization and Photocatalytic Activity of Mg‐Impregnated ZnO–SnO2 Coupled Nanoparticles

ZnO–SnO₂ nanoparticles were prepared by coprecipitation method; then Mg, with different molar ratios and calcination temperatures, was loaded on the coupled nanoparticles by impregnation method. The synthesized nanoparticles were characterized by X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X‐ray spectroscopy (EDX), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), and Brunauer–Emmett–Teller (BET) techniques. Based on XRD results, the ZnO–SnO₂ and Mg/ZnO–SnO₂ nanoparticles were made of ZnO and SnO₂ nanocrystallites. According to DRS spectra, the band gap energy value of 3.13 and 3.18 eV were obtained for ZnO–SnO₂ and Mg/ZnO–SnO₂ nanoparticles, respectively. BET analysis revealed a Type III isotherm with a microporous structure and surface area of 32.051 and 49.065 m² g^?1 for ZnO–SnO₂ and Mg/ZnO–SnO₂, respectively. Also, the spherical shape of nanocrystallites was deduced from TEM and FESEM images. The photocatalytic performance of pure ZnO–SnO₂ and Mg/ZnO–SnO₂ was analyzed in the photocatalytic removal of methyl orange (MO). The results indicated that Mg/ZnO–SnO₂ exhibited superior photocatalytic activity to bare ZnO–SnO₂ photocatalyst due to high surface area, increased MO adsorption and larger band gap energy. Maximum photocatalytic activity of Mg/ZnO–SnO₂ nanoparticles was obtained with 0.8 mol% Mg and calcination temperature of 350°C.     

Shape-controlled zinc(II) oxide nanomaterial constructed from three-dimensional zinc(II) coordination complex

Hydrothermal synthetic method has been used to prepare complex [ZnL]_n (1) (H₂L = 4-[(1H-imidazol-4-yl)methylamino]benzoic acid) as spherical microparticles. Slow morphological changes from small spindle-shaped particles to smoother spherical particles in the growth process of complex 1 were observed. Subsequently complex 1 was used as precursor as well as sacrificial template to synthesize hexagonal ZnO nanomaterials by calcination in air. The structure of the final products and the formation process were characterized by measurements of X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The formation mechanism of the final nanorods was proposed on the basis of the structural change of complex 1 in the calcination process. The photocatalytic properties of complex 1 and prepared ZnO have also been studied, and the results showed that all these nano-/micromaterials have photocatalytic properties and ZnO formed under lower calcinated temperature has higher photocatalytic activity.     

Calcination temperature-dependent morphology of photocatalytic ZnO nanoparticles prepared by an electrochemical–thermal method

ZnO nanoparticles (NPs) with tunable morphologies were synthesized by a hybrid electrochemical–thermal method at different calcination temperatures without the use of any surfactant or template. The NPs were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction, dynamic light scattering, thermogravimetry–differential thermal analysis, scanning electron microscope and N₂ gas adsorption–desorption studies. The FT-IR spectra of ZnO NPs showed a band at 450 cm^?1, a characteristic of ZnO, which remained fairly unchanged at calcination temperatures even above 300 °C, indicating complete conversion of the precursor to ZnO. The products were thermally stable above 300 °C. The ZnO NPs were present in a hexagonal wurtzite phase and the crystallinity of ZnO increased with an increasing calcination temperature. The ZnO NPs calcined at lower temperature were mesoporous in nature. The surface areas of ZnO NPs calcined at 300 and 400 °C were 51.10 and 40.60 m² g^?1, respectively, which are significantly larger than commercial ZnO nanopowder. Surface diffusion has been found to be the key mechanism of sintering during heating from 300 to 700 °C with the activation energy of sintering as 8.33 kJ mol^?1. The photocatalytic activity of ZnO NPs calcined at different temperatures evaluated by photocatalytic degradation of methylene blue under sunlight showed strong dependence on the surface area of ZnO NPs. The ZnO NPs with high surface area showed enhanced photocatalytic activity.     

沉淀煅烧法合成(CuAg)0.15In0.3Zn1.4S2光催化剂及可见光下的制氢性能

研究了沉淀煅烧法制备的纳米级(CuAg)_0.15In_0.3Zn_1.4S₂光催化剂以及产氢效率,并采用X射线衍射、透射电镜、扫描电镜、N₂吸附-脱附、紫外-可见吸收光谱等手段对催化剂进行了表征. 结果表明,(CuAg)_0.15In_0.3Zn_1.4S₂的结晶度、比表面积和吸收可见光能力与煅烧温度和煅烧时间有关. 在可见光下,以KI为电子给体,考察了不同条件对光催化产氢能力的影响. 发现在600℃煅烧5h时所制的(CuAg)_0.15In_0.3Zn_1.4S₂光催化剂产氢活性最高,产氢速率为1750 μmol g^-1 h^-1,量子效率在420±5nm达到12.8%,比未煅烧催化剂的光催化活性提高了约6倍.     

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,characterization and activity evaluation of p–n junction photocatalyst p-NiO/n-ZnO

In this paper, p–n junction photocatalyst NiO/ZnO was prepared by the sol–gel method using Ni (NO₃)₂ and zinc acetate as the raw materials. The structural and optical properties of the p–n junction photocatalyst NiO/ZnO were characterized by X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) analysis, UV–Vis diffuse reflection spectrum (DRS) and the fluorescence emission spectra. The photocatalytic activity of the photocatalyst was evaluated by photocatalytic reduction of Cr₂O₇ ²⁻ and photocatalytic oxidation of methyl orange (MO). The results showed that the photocatalytic activity of the p–n junction photocatalyst NiO/ZnO is much higher than that of ZnO on the photocatalytic reduction of Cr₂O₇ ²⁻. However, the photocatalytic activity of the photocatalyst is much lower than that of ZnO on the photocatalytic oxidation of methyl orange. Namely, the p–n junction photocatalyst NiO/ZnO has higher photocatalytic reduction activity, but lower photocatalytic oxidation activity. The heat treatment condition also influences the photocatalytic activity strongly, and the best preparation condition is about 400 °C for 2 h. Effect of the heat treatment condition on the photocatalytic activity of the photocatalyst was also investigated. The mechanisms of influence on the photocatalytic activity were discussed by the p–n junction principle.     

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.     

Synthesis of nano-sized Ag3PW12O40/ZnO heterojunction as a photocatalyst for degradation of organic pollutants under simulated sunlight

With the rapid development of the world economy, water pollution has become increasingly serious. The photocatalytic degradation of pollutants is one of the most promising environmental treatment techniques. In this study, novel Ag₃PW₁₂O₄₀/ZnO nanoheterojunction was successfully constructed via a chemical process and was then characterized using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, diffuse reflectance spectroscopy, Brunauer-Emmett-Teller analysis, and photoluminescence measurements. The synthesized nanoheterojunction exhibited good crystallinity and dispersity. The particle diameter of the composite was approximately 800 nm, the bandgap was 2.92 eV, and the specific surface area was approximately 10.5 m².g^?1. Under optimum conditions, the photocatalyst degraded 82.1% RhB in 60 min. Moreover, the novel Ag₃PW₁₂O₄₀/ZnO heterojunction also exhibited an excellent recycling stability. Hydroxyl radicals, superoxide radicals, and holes played important roles in the photocatalytic degradation process. A possible mechanism for the enhanced photocatalytic performance of the nanoheterojunction was proposed. This work provides a strong foundation for the application of Ag₃PW₁₂O₄₀/ZnO nanoheterojunction for treating environmental organic pollutants.     

溶胶-凝胶法制备In-Cd纳米复合氧化物及其气敏性能研究

采用溶胶凝胶法制备了In20rCdln2O4和CdO-Cdln2O4纳米复合氧化物,利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对复合材料的形貌和结构进行表征,并对其进行了乙醇、丙酮等多种气体的气敏性能测试.结果表明Cdln2O4材料复合h12O3和CdO后显著提高了对丙酮和乙醇气体的灵敏度和选择性.     

Novel Bi/BiOBr/AgBr composite microspheres: Ion exchange synthesis and photocatalytic performance

Novel Bi/BiOBr/AgBr composite microspheres were prepared by a rational in situ ion exchange reaction between Bi/BiOBr microspheres and AgNO₃. The characteristic of the as-obtained ternary microspheres was tested by X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDS), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence (PL). Under visible light irradiation, Bi/BiOBr/AgBr microspheres exhibited an excellent photocatalytic efficiency for rhodamine B (RhB) degradation, which was about 1.4 and 4.9 times as high as that of Bi/BiOBr and BiOBr/AgBr, demonstrating that the highest separation efficiency of charge carriers in the heterostructured Bi/BiOBr/AgBr. The photocatalytic activity of Bi/BiOBr/AgBr microspheres just exhibited a slight decrease after three consecutive cycles. The photocatalytic mechanism investigation confirmed that the superoxide radicals (O₂^•−) were the dominant reactive oxygen species for RhB degradation in Bi/BiOBr/AgBr suspension.     

Investigation on synthesis and microstructure of potassium tetratitanate

Potassium tetratitanate K₂Ti₄O₉ was synthesized from the anatase-K₂CO₃ starting materials by the heating calcination. DTA, TG, DTG and XRD methods were used to study the formation of intermediate compounds and the final product. The characterization of the K₂Ti₄O₉ crystals was carried out by means of scanning electron microscope (SEM).     

Synthesis of porous ZnO nanospheres for gas sensor and photocatalysis

Monodispersed porous ZnO nanospheres with diameters about 400–600 nm were successfully fabricated by a facile and effective cationic surfactant assisted selective etching strategy. The as-synthesized ZnO materials were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope and N₂ adsorption–desorption. These samples were used as the gas sensor, showing the high, stable and fast response to acetone, revealing the potential application as gas sensor to detect acetone. In addition, the photocatalytic degradation property of the porous ZnO nanospheres for methyl orange (MO) under UV irradiation was investigated. The degradation efficiency of MO reaches 96 % of the porous ZnO samples after 50 min of UV-light irradiation.