Mesoporous Indium Oxide Research Articles

Ag-nanoparticles-anchored mesoporous In2O3 nanowires for ultrahigh sensitive formaldehyde gas sensors

As the core component of gas sensors, the sensing mediums with excellent gas-sensing performance are strongly required. Herein, Ag nanoparticles were implanted into mesoporous indium oxide nanowires (In2O3 NWs) to form Ag-loaded In2O3 NW. All results indicated that Ag nanoparticles are well-dispersed in mesopores of In2O3 NWs and significantly affect specific surface area and interface oxygen vacancies. Moreover, Ag-loading tremendously improves the formaldehyde (HCHO) gas-sensing performance of Ag-loaded In2O3 sensors. Owing to Ag catalysis, the operating temperature decreases from 210 ℃ for In2O3 sensor to 150 ℃ for Ag-loaded In2O3 sensor. Ag0.025-In2O3 sensor exhibits the highest response (877.3) to 10 ppm HCHO for more oxygen vacancies and Ag spillover effect, which is about 33 times of In2O3 sensor. The formation of Schottky heterojunctions at the interface between Ag and In2O3 leads to the electron transition from In2O3 to Ag, which increases the resistance in air and HCHO gas for Ag-loaded In2O3 sensors.

Synthesis and mesoporous-structures of indium oxide nanowires for high sensitivity formaldehyde gas sensor

Mesoporous indium oxide nanowires (In2O3 NWs) were synthesized using ordered mesoporous SBA-15 silica as hard templates with nanocasting method, and then the bundled In2O3 nanowires (In2O3 BNWs) were separated from the dispersed In2O3 nanowires (In2O3 DNWs) by centrifugation technique. From the characterization with XRD, SEM, TEM, UV–vis spectra and nitrogen adsorption-desorption isotherm, both samples present the same mesoporous-structures, diameter and the similar defects due to the same synthesis conditions. The specific surface area (57.37 m2/g) of In2O3 BNWs are higher than that of In2O3 DNWs for the better mesoporous-structures. In2O3 BNWs with the smaller grain size and higher surface area absorb more oxygen in air and increase the thickness of electron depletion layer, leading to the larger change of resistance in air. Therefore, In2O3 BNWs sensor presents the better sensitivity (26.16) to formaldehyde than In2O3 DNWs sensor at optimized operating temperature owing to the high surface area and small grain size.

Indium Oxide/Carbon Nanotube/Reduced Graphene Oxide Ternary Nanocomposite with Enhanced Electrochemical Supercapacitance

Abstract Electrochemical supercapacitance performance of a ternary nanocomposite composed of mesoporous indium oxide (In2O3) nanocube crystals (size ∼50 nm) embedded in carbon nanotubes (CNT) and reduced graphene oxide (RGO) prepared by hydrothermal method is reported. A glassy carbon electrode modified with the In2O3/CNT/RGO nanocomposite material exhibited excellent electrochemical performance with a large specific capacitance of 1273 F g−1 at 5 mV s−1 and 948 F g−1 at 1 A g−1. The composite electrode showed excellent cyclic stability without any capacity loss after 5000 charge/discharge cycles. Furthermore, ∼75% capacitance retention was observed at high scan rate of 200 mV s−1. These results indicate that the novel mesoporous In2O3 cubes composited with π-electron rich conductive nanocarbons CNT and RGO would be useful as electrode material for advanced supercapacitors.

Biphasic Voltammetry and Spectroelectrochemistry in Polymer of Intrinsic Microporosity\u20144-(3-Phenylpropyl)-Pyridine Organogel/Aqueous Electrolyte Systems: Reactivity of MnPc Versus MnTPP

A hydrophobic polymer of intrinsic microporosity (PIM-EA-TB) is employed to stabilize an organogel/aqueous electrolyte phase boundary based on an organic water-insoluble 4-(3-phenylpropyl)-pyridine phase. The organogel with electrocatalytic metal complexes embedded is immobilized on glassy carbon or on transparent mesoporous tin-doped indium oxide (ITO) electrodes. Liquid/liquid ion transfer voltammetry is investigated for a 4-(3-phenylpropyl)-pyridine organogel/aqueous electrolyte interface for two types of redox systems: tetraphenylporphyrinato-Mn(III/II) (MnTPP) and phthalocyanato-Mn(III/II) (MnPc). Electron transfer is shown to be coupled to reversible liquid/liquid anion transfer processes for PF6−, ClO4−, SCN−, and NO3−, with a change in mechanism for the more hydrophilic anions Cl−, F−, and SO42−. In situ UV-Vis spectroelectrochemistry reveals reversible Mn(III/II) redox processes coupled to ion transfer for MnTPP. But further complexity and a detrimental side reaction are observed for MnPc causing gradual loss of the electrochemical response in the presence of dioxygen.Graphical ᅟ

Enhanced photo-catalytic activity of ordered mesoporous indium oxide nanocrystals in the conversion of CO2 into methanol

ABSTRACTOrdered mesoporous indium oxide nanocrystal (m-In2O3) was synthesized by nanocasting technique, in which highly ordered mesoporous silca (SBA-15) was used as structural matrix. X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halanda (BJH) studies were carried out on m-In2O3 and the results revealed that this material has a highly ordered mesoporous surface with reduced grain size, increased surface area and surface volume compared to the non porous indium oxide. The diffuse reluctance spectrum exhibited substantially improved light absorption efficiency in m-In2O3 compared to normal indium oxide, however, no considerable change in the band gap energies of these materials was observed. When m-In2O3 was used as a photo-catalyst in the photo-catalytic process of converting carbon dioxide (CO2) into methanol under the pulsed laser radiation of 266-nm wavelengths, an enhanced photo-catalytic activity with the quantum efficiency of 4.5% and conversion efficiency of 46.3% were observed. It was found that the methanol production yield in this chemical process is as high as 485 µlg−1 h−1 after 150 min of irradiation, which is substantially higher than the yields reported in the literature. It is quite clear from the results that the introduction of mesoporosity in indium oxide, and the consequent enhancement of positive attributes required for a photo-catalyst, transformed photo-catalytically weak indium oxide into an effective photo-catalyst for the conversion of CO2 into methanol.

Amphiphilic Block Copolymer Templated Synthesis of Mesoporous Indium Oxides with Nanosheet-Assembled Pore Walls

A solvent evaporation induced coassembly approach combined with a comburent CaO2-assisted calcination strategy was employed for the synthesis of ordered mesoporous indium oxides by using lab-made high-molcular weight amphiphilic diblock copolymer poly(ethylene oxide)-b-polystyrene (PEO-b-PS) as a template, indium chloride as an indium source, and THF/ethanol as the solvent. The obtained mesoporous indium oxide materials exhibit a large pore size of ∼14.5 nm, a surface area of 48 m2 g–1, and a highly crystalline In2O3 nanosheets framework, which can facilitate the diffusion and transport of gas molecules. By using an integrated microheater as the chemresistance sensing platform, the obtained mesoporous indium oxides were used as sensing materials and showed an excellent performance toward NO2 at a low working temperature (150 °C) due to their high porosity and unique crystalline framework. The limit of detection (LOD) of the microsensor based on mesoporous indium oxides can reach a concentration as low as ...

One-step synthesis of multi-modal pore systems in mesoporous In2O3: A detailed study

Ordered mesoporous silica phases (e.g. KIT-6, SBA-15) are used as structure matrices for negative replica structures of mesoporous In2O3. We present a detailed study on how the controlled synthesis of mono-, bi- and trimodal pore systems in the products is accomplished by systematic variation of the procedure of infiltrating a precursor species (In(NO3)3) into the pores of the silica matrix and subsequent thermal conversion into In2O3. Melt impregnation and conversion in a closed reactor facilitates a one-step casting process for ordered mesoporous indium oxide (In2O3). We present a model based on variation of the pore filling.

Synthesis, Characterization, and Gas-Sensing for Trimethylamine of Mesoporous Ni-Doped Indium Oxide

Ni-doped mesoporous indium oxide has been successfully obtained by a simple and effected in-situ nanocasting method. The results characterized indicated that powders had a good crystalline structure, and the synthesis was successfully controlled in nanoscale (meso-structure). The gas sensor based on Ni-doped mesoporous In2O3 exhibit good trimethylamine (TMA) sensing properties, and a possible mechanism was aSubscript textlso provided.

Humidity Sensing Property of Mesoporous Indium Oxide

In this paper, mesoporous indium oxide has been synthesized by the hard template route from the SBA-15 silica template. The results characterized from XRD, and N2 adsorption-desorption demonstrated that the synthesis can be controlled successfully in nanometer (meso-structure) scale. The obtained sample was investigated as humidity sensing material by coating on a ceramic plate, and the humidity sensing performance can be enhanced up to more than three orders of magnitude without any doping. Further testing proved that it is a promising humidity sensing material and can be widely used, and a possible mechanism was also provided.

Photocatalytic ozone sensor based on mesoporous indium oxide: Influence of the relative humidity on the sensing performance

Mesoporous In 2O 3, synthesized by a nanocasting procedure, is used as a resistive gas sensor for ozone in very low concentrations (from 20 ppb to 2.4 ppm) at room temperature. Its sensing performance is substantially increased by illumination with blue light (460 nm, 2.7 eV). For low ozone concentrations the sensor response increases with increasing humidity. However, higher humidity also results in the occurrence of a saturation of the response at lower ozone concentrations; this is rationalized by assuming a poisoning of surface active sites by hydroxyl groups.

Synthesis and characterization of mesoporous indium oxide for humidity-sensing applications

An ordered mesoporous In 2O 3 material with crystalline walls has been synthesized through the nanocasting method. It was investigated as an impedance-type humidity sensor for the detection of water vapor. A nanostructured In 2O 3 matrix has been obtained by the hard template route from the KIT-6 silica template. The crystalline In 2O 3 belonged to the Ia3d space group, and its structure was characterized by X-ray diffraction (XRD), N 2 adsorption–adsorption, and transmission electron microscopy (TEM). The sensor based on mesoporous In 2O 3 showed excellent performance in terms of humidity changes and favorable stability. Through the analysis of its semiconductor characteristics, Kelvin equation, and complex impedance, we found that the 3D mesoporous structure contributes greatly to the improvement of humidity-sensitive properties. A possible mechanism was established to explain the excellent performance of the mesoporous In 2O 3-made humidity-sensing device. The evaluation of its electrical characterization and the establishment of its sensing mechanism shows that mesoporous In 2O 3 is a good candidate for developing humidity sensors. It has potential applications in the chemical-sensing field.

H 2S-sensing properties of Pt-doped mesoporous indium oxide

Pt-doped mesoporous indium oxide (In 2O 3) has been successfully obtained by a simple and effective in situ nanocasting method. The resultant samples were characterized by XRD, FE-SEM, TEM, N 2 physisorption, XPS and EDX. The gas sensing properties for hydrogen sulfide (H 2S) of the Pt-doped mesoporous In 2O 3 specimens were also examined. The results exhibit those In 2O 3 specimens possess much higher response to H 2S even at low concentration of 2 ppm and a lower optimum working temperature of 150 °C. A possible mechanism was also provided to explain the improvement of the sensing properties.

Preparation and characterization of mesoporous indium oxide

Indium oxide nanocrystals with mesoporous structure were successfully synthesized by using triblock copolymer as a template, and characterized by thermogravimetry-differential scanning calorimeter (TG-DSC), X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and N2 adsorption. A high EO/PO ratio is thought to be the key point to prepare mesoporous In2O3. The results show that the average pore diameter of the products is 6 nm, the BET surface area is 54.78 m2/g, and the adsorbing pore volume is 0.345 cm3/g. After comparing with normal indium oxide nanoparticles by BET test, mesoporous indium oxide demonstrates a large difference in adsorbing pore volume and average pore diameters from normal ones.

Mesoporous indium oxide synthesized via a nanocasting route

The synthesis of crystalline mesoporous indium oxide by using a mesoporous carbon (CMK-3) as hard template is described. Transmission electron microscopy (TEM) exhibits the presence of mesoporous structure in our sample and the corresponding wide-angle X-ray diffraction (XRD) pattern confirmed the crystalline wall of sample. N 2 adsorption measurement exhibits the synthesized crystalline mesoporous indium oxide possesses a specific surface area of 39 m 2/g and the total pore volume of 0.17 cm 3/g, and the corresponding pore size distribution curve reveals the presence of a mesopore of 7.0 nm in maximum. Our work demonstrates that the maintenance of the ordered structure of carbon template is very significant for obtaining high quality replicas via the nanocasting route.