As-prepared In2O3 Research Articles

Enhanced methanol gas-sensing performance of Ce-doped In2O3 porous nanospheres prepared by hydrothermal method

In this work, novel Ce-doped In2O3 porous nanospheres have been prepared by calcining precursors obtained via a facile template-free hydrothermal method. The morphology and structure of the as-prepared samples were characterized by X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). FESEM and TEM images showed that as-prepared In2O3 samples were uniform and well-dispersed nanospheres with size of 200–300nm, which were composed of numerous small nanocrystallites. XRD, ICP, and XPS spectroscopy were used to identify the products structure and the peak shifts in spectroscopies confirmed that the Ce element was doped in cubic In2O3. Compared with pure In2O3 samples, Ce-doped In2O3 porous nanospheres showed excellent sensing performance toward methanol at the operating temperature of 320°C and had a response of about 35.2–100ppm methanol, which was much higher than that of the sensor based on pure In2O3 nanospheres. In addition, Ce-doped In2O3 porous nanospheres exhibited good selectivity and long-term stability.

Microwave Hydrothermal Synthesis and Characterization of In<sub>2</sub>O<sub>3 </sub>Nanocrystalline

In2O3 nanopowder was successfully synthesized using microwave-hydrothermal method; by a very simple fast reaction between InCl3 and urea in aqueous solution contain 1% polyethylene glycol. The products were characterized by the techniques of X-ray diffraction (XRD), Scanning electron microscope (SEM) and Fluorescent spectrum. The result shows that as-prepared In2O3 nanopowder is cubic phase, the morphology is square composed of many particles.

Radiation induced synthesis of In2O3 nanoparticles - part 1: synthesis of In2O3 nanoparticles by sol-gel method using un-irradiated and γ-irradiated indium acetate

Pure phase of In2O3 nanoparticles were synthesized by sol-gel method in non-aqueous medium using un-irradiated and γ-irradiated indium acetate precursors. The as-prepared In2O3 nanoparticles were characterized by XRD, FT-IR, SEM, TEM and TG techniques. The results showed that pre-irradiation to indium acetate with 102 KGy γ-ray absorbed dose has significant effects on the shape and size of the as-synthesized In2O3 nanoparticles. In case of un-irradiated precursor, the SEM images show agglomerated and disordered spherical nanoparticles. In γ-irradiated case the particles showed coral-like structure. The as-synthesized In2O3 nanoparticles prepared using γ-irradiated precursor showed higher thermal stability compared with those prepared using un-irradiated one. The results were discussed in view of the role of γ-irradiation on the morphology and thermal behavior of In2O3 nanoparticles.

Synthesis and characterization of In2O3nanoparticles

Metal-oxide nanostructures have elicited increasing interest in both fundamental and applied sciences. Among metal oxide nanostructures, In2O3 has the potential for use asa semiconductor material. This article provides details on studies carried out thus far for the synthesis and the characterization of In2O3 nanostructures. In this research, various techniques were investigated for the fabrication of diverse and fascinating spherical shaped In2O3 nanostructures. Brunauer- Emmett-Teller (BET) analyses of the In2O3 nanostructures through detailed refinements of the structure of the In2O3 nanoparticles by using the Rietveld method, followed by microstructural analyses using scanning electron microscopy/ transmission electron microscopy (SEM/TEM) and a chemical composition analysis are presented and discussed. Decreasing crystallinity with an improvement in specific surface area was observed from the structural characterization. The energy dispersive analysisresults showed that the as-prepared In2O3 powder sample was stoichiometric, containing almost equal proportions of indium and oxygen. The microstructural analysis (TEM and SEM) demonstrated precise control over the diameters of the nanoparticles, which is an important advantage of the solution combustion approach.

Optical, electrical and sensing properties of In2O3 nanoparticles

In this work, various techniques such as differential scanning calorimetry-thermogravimetric analysis (DSC-TGA), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible-near infrared (UV-vis-NIR), photoluminescence (PL), >as well as electrical and sensor techniques have been used for the characterization of indium oxide (In2O3) nanoparticles. Here, we also provide insight regarding the optical and electrical characteristics of In2O3 nanostructures. The impact of highly sensitive and fast responding gas sensors using In2O3 nanostructures is also discussed. It is found that the as-prepared In2O3 powder is a pure single phase and is stable up to 800°C. The size of the particles is in the range of 12nm as determined by transmission electron microscopy (TEM). The band gap was found to vary linearly with the annealing temperature. A good sensitivity up to 400ppm was obtained for ethanol and a mechanism is proposed.

In(OH)3particles from an ionic liquid precursor and their conversion to porous In2O3particles for enhanced gas sensing properties

The ionic liquid precursor tetrabutylammonium hydroxide (TBAH) is used to synthesize In(OH)3 particles. The ionic liquid TBAH is demonstrated to be effective for the synthesis of In(OH)3 nanorods with a controlled size. The effect of the indium salt and the added water amount on the final products is investigated. The synthesized In(OH)3 nanorods could be further transformed into porous In2O3 rod particles. Specifically, the gas sensing properties of the synthesized porous In2O3 rod particles to various organic compounds (methanol, ethanol, isopropanol, butanol, ethyl acetate and toluene) exhibit remarkable sensitivities, low detection limits and fast response–recovery times, which are superior to the reported In2O3 based sensors. The as-prepared porous In2O3 rod-based sensors thus demonstrate their potential applications in detecting chemical contaminants and dangerous gases.

Nearly monodispersed In(OH)3hierarchical nanospheres and nanocubes: tunable ligand-assisted synthesis and their conversion into hierarchical In2O3for gas sensing

In(OH)3 nanomaterials with different morphologies or hierarchical structures, such as nanoparticles, monodispersed hierarchical nanocubes and nanospheres, have been successfully synthesized via a ligand-assisted aqueous process. The shape and size of these as-prepared architectures can be tuned effectively by controlling the reaction conditions, such as the molar ratio of ligand/In3+ and different ligands. Further studies reveal that both Na3cit and urea are necessary for the formation of monodispersed hierarchical nanospheres and nanocubes. Furthermore, In2O3 nanoparticles and monodispersed hierarchical nanocubes and nanospheres with well-defined morphologies of the precursors can be also obtained by annealing the corresponding In(OH)3 samples. The gas sensing properties of the as-prepared In2O3 samples demonstrate that hierarchical In2O3 architectures exhibit a superior response to ethanol gas, and the hierarchical In2O3 nanocubes have excellent selectivity and sensitivity. Further more, XPS spectra and N2 adsorption–desorption isotherms achieve a deeper understanding of the effects of the final product morphologies on their gas sensing properties.

Preparation of Electrospun In<sub>2</sub>O<sub>3</sub>/CdO Composite and Its Formaldehyde-Sensing Properties

In(NO3)3/polyvinyl pyrrolidone (PVP) nanofiber precursors were synthesized using a traditional electrospinning method, and were then annealed at 500, 600, and 700 °C to form In2O3 nanofibers. The as-prepared In2O3 nanofibers were characterized using X-ray diffraction (XRD), thermal gravimetry and differential thermal analysis (TG/DTA), and field-emission scanning electron microscopy (FE-SEM). The results show that the In2O3 nanofibers crystallize well, with a small average grain size (about 24 nm) and a good mesoporous structure, when annealed at 500 °C. The In2O3 nanofibers annealed at the three temperatures were further used to fabricate gas sensors. The test results show that the sensor based on In2O3 annealed at 500 °C has the highest response (about 7) to 10×10 - 6 (volume fraction, φ) formaldehyde (HCHO) at an operating temperature of 240 °C. CdO nanoparticles were also prepared using the same method; XRD and FE-SEM show that the average grain size of CdO is about 68 nm. Finally, the as-prepared In2O3 nanofibers were mixed with the as-prepared CdO in molar ratios of 1:1, 10:1, and 20:1, and the mixtures were used to fabricate gas sensors. The HCHO-sensing properties of the sensors based on pure In2O3 and In2O3/CdO composites with different molar ratios were investigated at each optimum temperature. The results show that the In2O3/CdO composite with a molar ratio of 10:1 has excellent

Preparation of nano-In<SUB align="right">2O<SUB align="right">3 thin films by spray pyrolysis for gas sensing application

We report preparation of nano-In2O3 thin films by a simple, inexpensive spray pyrolysis (SP) method and their gas sensing application. Nano-In2O3 thin films were prepared by using indium trichloride in de-ionised water as a precursor at substrate temperature 350°C. As-prepared In2O3 thin films were used for further characterisation after annealing at temperature 550°C for 30 min. The structural and surface morphological properties of the films were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. These films were tested to various gases at different operating temperature ranging from 50°C to 450°C. A high value of sensitivity is obtained for ethanol at operating temperature of 350°C for 80 ppm. The mechanism of ethanol sensing by the In2O3 thin film is explained on the basis of adsorbed oxygen on the sensor surface. The In2O3 thin films exhibited good sensitivity and rapid response-recovery characteristics to ethanol.

Hierarchical hollow microsphere and flower-like indium oxide: Controllable synthesis and application as H2S cataluminescence sensing materials

In the present work, In2O3 hierarchical hollow microsphere and flower-like microstructure were achieved controllably by a hydrothermal process in the sodium dodecyl sulfate (SDS)-N,N-dimethyl-formamide (DMF) system. XRD, SEM, HRTEM and N2 adsorption measurements were used to characterize the as-prepared indium oxide materials and the possible mechanism for the microstructures formation was briefly discussed. The cataluminescence gas sensor based on the as-prepared In2O3 was utilized to detect H2S concentrations in flowing air. Comparative gas sensing results revealed that the sensor based on hierarchical hollow microsphere exhibited much higher sensing sensitivity in detecting H2S gas than the sensor based on flower-like microstructure. The present gas sensor had a fast response time of 5s and a recovery time of less than 25s, furthermore, the cataluminescence intensity vs. H2S concentration was linear in range of 2–20μgmL−1 with a detection limit of 0.5μgmL−1. The present highly sensitive, fast-responding, and low-cost In2O3-based gas sensor for H2S would have many practical applications.

Biomorphic synthesis and gas response of In2O3 microtubules using cotton fibers as templates

Biomorphic In2O3 microtubules were prepared using cotton as biotemplates. The structural and microscopy characterization has been carried out with X-ray diffraction and scanning electron microscopy. XRD patterns confirm the formation of In2O3 with cubic phase. The results of scanning electron microscopy revealed that the obtained In2O3 microtubules are in the range of 30–60μm in length, 8–10μm in width, and about 300nm in thickness. The In2O3 microtubules were composed of numerous spherical In2O3 nanocrystals with the nearly uniform size about 30nm. The gas sensing performance of as-prepared In2O3 nanocrystals was investigated. It is found that In2O3 microtubules calcined at 500°C exhibit good selectivity for formaldehyde with rapid response and high sensitivity at 260°C.

In2O3 hollow spheres: One-step solvothermal synthesis and gas sensing properties

Hollow In2O3 spheres were prepared via a P123-assisted one-step solvothermal process for the first time. Ethanol medium played a key role in the direct cubic In2O3 phase formation whereas the triblock copolymer acted as a structure directing agent in the formation of the hollow spheres. The gas sensing properties of the as-prepared In2O3 hollow spheres were investigated. Compared to the products synthesized without P123, the In2O3 hollow spheres exhibited much faster response and higher sensitivity toward HCHO vapor.

Interfacial Charge Carrier Dynamics of the Three-Component In2O3–TiO2–Pt Heterojunction System

The interfacial charge carrier dynamics of the three-component semiconductor–semiconductor–metal heterojunction system were investigated and presented for the first time. The samples were prepared by selectively depositing Pt nanoparticles on the TiO2 surface of In2O3-decorated TiO2 nanobelts (In2O3–TiO2 nanobelts (NBs)) using the typical photodeposition method. For In2O3–TiO2 NBs, because of the difference in band structures between In2O3 and TiO2, the photoexcited electrons of In2O3 nanocrystals would preferentially transfer to TiO2 NBs to cause charge carrier separation. With the introduction of Pt on TiO2 surface, a fluent electron transfer from In2O3, through TiO2, and eventually to Pt was achieved, giving rise to the increasingly pronounced charge separation property for the as-prepared In2O3–TiO2–Pt NBs. The remarkable charge separation of the samples was revealed with the corresponding photocurrent measurements. Time-resolved photoluminescence spectra were measured to quantitatively analyze the el...

Highly porous metal oxide polycrystalline nanowire films with superior performance in gas sensors

In this work, we report for the first time a simple two-step route to fabricate a novel porous metal oxide film composed of polycrystalline nanowires with ultra-small nanoparticles, good interconnectivity between nanoparticles, and a high density of ultra-fine nanopores. The as-prepared metal oxide films combine the advantages of small crystal size, high surface-to-volume ratio, and one-dimensional-nanowire-induced unique charge transport paths (with correspondingly high interconnectivity). Taking In2O3 as an example, porous In2O3 films, composed of polycrystalline In2O3 nanowires with ultra-small nanocrystals (less than 10 nm) and a high density of ultra-fine nanopores (1.6–3.1 nm), have shown very high sensitivity and good reproducibility towards ethanol gas, which are 10–20 times higher than for In2O3 octahedra and commercial SnO2 thick films. The response/recovery speeds of the as-prepared porous In2O3 films are also 5–6 times higher than for In2O3 octahedra, SnO2 nanobelts, and commercial SnO2 thick films. We believe that such metal oxide flexible films made from highly porous nanowires will replace their traditional thick film counterparts, not only in gas sensors but also in other functional devices, such as batteries, supercapacitors, solar cells, etc.

High-aspect-ratio single-crystalline porous In2O3 nanobelts with enhanced gas sensing properties

With greatly enhanced surface-to-volume ratios, one-dimensional (1-D) nanostructures are believed to be able to deliver better performance as chemical sensors. In this paper, by using a hydrothermal-annealing process, we reported the synthesis of porous In2O3 nanobelts with a high aspect ratio. By annealing hydrothermally-synthesized single crystalline ultralong InOOH nanobelts, single crystalline porous In2O3 nanobelts with an aspect ratio larger than 100 are obtained on a large scale. The gas sensing properties of the as-prepared porous In2O3 nanobelts were investigated, and they can detect different chemicals (methanol, ethanol, and acetone) down to ppb level. The results also showed that the nanobelts exhibited excellent gas sensing performance in terms of high sensitivity, low detection limit, fast response and recovery times, and sensing selectivity.