Surface Of In2O3 Research Articles

In–N–In Sites Boosting Interfacial Charge Transfer in Carbon-Coated Hollow Tubular In2O3/ZnIn2S4 Heterostructure Derived from In-MOF for Enhanced Photocatalytic Hydrogen Evolution

A hierarchical hollow tubular In2O3/ZnIn2S4 heterostructure was rationally designed by growing thin-layered ZnIn2S4 on the surface of carbon-coated hollow tubular In2O3 (C/HT-In2O3) that was derive...

Construction of Dual‐tight Contact Interface in Z‐scheme System of In2O3/OV/In2S3 for Enhancing Photocatalytic Performance

AbstractThe novel Z‐scheme photocatalytic system of In2O3/OV/In2S3 has been obtained by a facile two‐step in situ deposition method, where oxygen vacancies and In2S3 are in situ located on the surface of In2O3 in sequence. In such a photocatalytic system, oxygen vacancy anchored tightly on the surface of In2O3 serves as an electron mediator, efficiently extracting electrons from In2O3 and modulating the electron transfer paths to facilize constructing a Z‐scheme system. Due to the presence of another tight contact interface between the In2O3 and In2S3, the transfer rate of electrons from In2O3 to In2S3 can be further accelerated. Therefore, the synergistic effect of the above‐mentioned dual‐tight contact interface over In2O3/OV/In2S3 Z‐scheme system simultaneously enhances the charge separation and transfer, resulting in the high performance of photocatalytic H2 evolution.

Significant enhancement of photocatalytic H2 production simultaneous with dye degradation over Ni2P modified In2O3 nanocomposites

The photocatalytic H2 production simultaneous with organic pollutant degradation has been received wide attention in resolving the problems of energy crisis and environmental pollution. In this study, for the first time, the Ni2P (NIP) nanoparticles are successfully loaded on the surface of In2O3 (INO) nanocubes, and the physical-chemical features of as-formed NIP/INO samples are comprehensively characterized by various technologies. Moreover, the photoreactivities of as-prepared NIP/INO nanocomposites are carefully investigated through the photocatalytic H2 evolution simultaneous with dye (Rhodamine B, RhB) degradation under simulated sunlight irradiation. It was found that the as-fabricated NIP/INO nanocomposites present the significantly enhanced H2 production and RhB degradation rates than that of pure INO nanocubes. Consequently, the optimum photocatalytic performance of as-synthesized photocatalyst is loaded by 7 wt% NIP (7-NIP/INO), whose the H2 evolution and RhB degradation rates are reached at 0.138 μmol h−1 and 16.12%, respectively, which are 10.6-folds and 1.6-folds higher than that of individual INO, even its photoactivity is superior than the 1 wt% Pt decorated INO. The greatly improved photocatalytic performance is due to the NIP as co-catalyst can not only promote the charge carries separation and transfer efficiency, but also provide the abundant reaction active sites. Our work highlights a simple strategy for the preparation of non-noble metal nanocomposites towards the renewable solar-driven photocatalysis applications by combining with earth-abundant Ni-based co-catalyst.

Oxygen vacancies enhancing acetone-sensing performance

Cd-doped In2O3 was synthesized by a facile solvothermal, template-free preparation method. The phase structure and properties were characterized by various methods. The surface of Cd-doped In2O3 became coarse compared with that of pure In2O3, according to the scanning electron microscopeimages, which enhanced the ability to absorb the gas. The electron paramagnetic resonance showed that the Cd-doped In2O3 can generate more defects and oxygen vacancies. By measuring the gas sensitivity, the response of Cd-doped In2O3 was 1.6 times than that of pure In2O3. Thus, Cd-doped In2O3 can promote gas-sensing performance compared with pure In2O3.

Unraveling the Surface Chemistry of CO Sensing with In2O3 Based Gas Sensors

The effect of water vapor on the physical and chemical characteristics of semiconducting metal oxides (SMOX), as well as the resulting varying in sensing behavior is a highly researched field. Up to now, most investigations have been done on SnO2 and there is limited information on other interesting materials. In this work, we explored In2O3 based gas sensors using DC resistance measurements combined with diffuse reflectance infrared Fourier transformed spectroscopy (DRIFTS). The effect of water vapor and its influence on the CO detection was examined. Three different materials were chosen with varying levels of humidity cross interference humidity on the detection of this analytic. In the electrical measurements, humidity has different effects on the baseline resistance. This is related to the different initial level of surface hydroxylation, confirmed by infrared measurements through isotopic exchange experiments. The exposure to CO shows a decrease of the identified In-O bands indicating a reduction of the surface. The formation of carbonates is favored on highly hydroxylated surfaces. It is found that their formation is a subsequent reaction with formed CO2. Carbonates do not have a significant electrical impact and their formation is significantly hindered in wet conditions suggesting that H2O and CO2 have the same adsorption sites on the surface of In2O3. The measurements in nitrogen show that the sensing of CO involves the oxygen in the lattice.

Acetone sensing characteristics of Fe2O3/In2O3 nanocomposite

Fe2O3 and In2O3 nanoparticles were prepared by a citric sol-gel method and mixed subsequently to form the (x)Fe2O3/(1 − x)In2O3 (x = 0, 0.05, 0.10, 0.15, 0.20, 0.50, 1) nanocomposites. XRD confirmed the separate phases of cubic In2O3 and orthorhombic Fe2O3 in the composites. At the prime working temperature of 200 °C, the 0.15Fe2O3/0.85In2O3 nanocomposite-based sensor showed the best acetone sensing performance among all sensors, including the highest gas response, sensitivity, selectivity and stability. Although the mean grain size was slightly increased upon adding Fe2O3 nanoparticles in larger sizes, which leaded to smaller BET surface area, the electron transfer from Fe2O3 to In2O3 across the heterostructure interface increased the electron concentration in the surface region of In2O3, which resulted in more adsorbed oxygen species on the surface of In2O3 and favored the subsequent acetone sensing process.

Impedance spectroscopy of electrochromic films of nanocrystalline tungsten (VI) oxide

The present paper study electrochromic films of nanocrystalline tungsten oxide (VI) by electrochemical impedance spectroscopy. Electrochromic films were obtained using the simplified technique of deposition of tungsten (VI) oxide from an aqueous dispersion on surface of transparent electrode In2O3. To obtain a uniform composition, the aqueous dispersion was treated with ultrasonic radiation, while the average particle size of tungsten oxide in the dispersion volume was from 30 to 70 nm. The prepared films had an amorphous structure and a crystalline structure was obtained by pyrolysis at a temperature of 250, 300, and 400 °C corresponding to different samples. The obtained nanocrystalline films were studied by electrochemical impedance spectroscopy in the frequency range from 1 to 106 Hz with an amplitude of an alternating voltage of 10 mV to determine the effect of temperature on the impedance of the films. The analysis data allowed us to determine the dependence of electrical conductivity on the volume of grains and the boundaries between crystals on the influence of temperatures on the structure properties of electrochromic films of nanocrystalline tungsten (VI) oxide.

Creating oxygen vacancies on porous indium oxide nanospheres via metallic aluminum reduction for enhanced nitrogen dioxide detection at low temperature

Investigating the correlation between the electronic structure of indium oxide materials with oxygen vacancy defects and their sensing property to nitrogen dioxide is important for future development of high-efficient sensing materials. For the first time, the defective structure of porous In2O3 nanospheres was introduced in a two-zone tube furnace using metallic Al as reducing agent. Texture characterizations show that In2O3 and In2O3-x are porous nanospheres assembled by small particles with the size of ca. 10–20 nm. The surface oxygen vacancy defects and electronic structure of samples were characterized by X-ray power diffraction, X-ray photoelectron spectroscopy, electron paramagnetic resonance, photoluminescence, ultraviolet-visible spectrophotometer and Hall analysis, and the sensing performance of samples to NO2 gas was evaluated. The results display that the porous In2O3-x nanospheres prepared at the reducing temperature of 300 °C (Vo-In2O3-300) exhibits improved response of 130 to 3 ppm NO2 at 80 °C, which is almost 2.5-folds as high as the response (55) of the porous In2O3 nanospheres. The sensing mechanism study carried out using DFT indicates that oxygen vacancies on the surface of In2O3 as donor level optimize the electron structure and electrical properties of materials, such as supplying more free-electrons in the conduction band, narrowing the band gap and improving the mobility of electrons, which result in the low energy barrier for the adsorption of NO2 molecules on the surface and in turn enhance the gas-sensing performance of In2O3. Therefore, this work can provide some instructive thoughts for constructing In2O3-based sensing materials for high-efficient nitrogen dioxide detection.

The Itinerant 2D Electron Gas of the Indium Oxide (111) Surface: Implications for Carbon- and Energy-Conversion Applications.

Transparent conducting oxides (TCO) have integral and emerging roles in photovoltaic, thermoelectric energy conversion, and more recently, photocatalytic systems. The functional properties of TCOs, and thus their role in these applications, are often mediated by the bulk electronic band structure but are also strongly influenced by the electronic structure of the native surface 2D electron gas (2DEG), particularly under operating conditions. This study investigates the 2DEG, and its response to changes in chemistry, at the (111) surface of the model TCO In2 O3 , through angle resolved and core level X-ray photoemission spectroscopy. It is found that the itinerant charge carriers of the 2DEG reside in two quantum well subbands penetrating up to 65 Å below the surface. The charge carrier concentration of this 2DEG, and thus the high surface n-type conductivity, emerges from donor-type oxygen vacancies of surface character and proves to be remarkably robust against surface absorbents and contamination. The optical transparency, however, may rely on the presence of ubiquitous surface adsorbed oxygen groups and hydrogen defect states that passivate localized oxygen vacancy states in the bandgap of In2 O3 .

Highly Efficient Degradation of Perfluorooctanoic Acid over a MnOx‐Modified Oxygen‐Vacancy‐Rich In2O3 Photocatalyst

AbstractDestructive removal of perfluoroalkyl substances (PFASs) from water has been an emerging concern, as the C−F bond cleavage requires energy‐consuming advanced oxidation approaches. The conventional photocatalyst materials exhibit insufficient PFAS degradation due to either a weak absorption ability towards PFASs or a limited reaction oxygen species (ROS) generation. Herein, In2O3, which has an excellent absorption ability towards perfluorooctanoic acid (PFOA), is chosen as the main catalyst materials. Oxygen vacancies are then generated on the surface of In2O3 to assist the PFOA adsorption. Further depositions of the MnOx cocatalyst on the surface of In2O3 are performed to enhance the ROS generation efficiency. Based on the above design, the MnOx‐modified oxygen‐vacancy‐rich In2O3 photocatalyst shows a remarkably improved PFOA photodegradation and defluorination efficiencies under the solar light irradiation as compared with the pristine and commercial In2O3. The photodegradation pathway of PFOA is investigated. The experimental results from the PFOA adsorption analysis and electron spin resonance (ESR) spectra confirm the enhanced adsorption ability and the higher ROS generation efficiency, respectively. The catalyst is further tested in the presence of different anions and cations, where rapid degradation of PFOA is also observed, indicating the potential of the composite materials applied in the practical treatment of PFAS‐contaminated water.

Ni metal coating boosting the thermoelectric performance of In2O3(ZnO)5 ceramics

A new approach was developed for enhancing the thermoelectric performance of In2O3(ZnO)5 ceramics. Ni coating layer on the surface of In2O3(ZnO)5 powders was prepared by chemical plating. The Ni-Coated In2O3(ZnO)5 powders was densified to composite bulk with Ni enrichment in the grain boundaries. The composite sample obtained a remarkably enhanced dimensionless thermoelectric figure of merit (ZT) of 0.39 at 973K, which is 3.6 times higher than that of a pristine In2O3(ZnO)5 sample.

Hollow In2O3@ZnFe2O4 heterojunctions for highly efficient photocatalytic degradation of tetracycline under visible light

In2O3@ZnFe2O4 hollow structure heterojunctions were synthesized by loading ZnFe2O4 nanosheets on the outer surface of hollow In2O3 and then employed for highly efficient photocatalytic degradation of tetracycline under visible light.

Ag-Modified In₂O₃ Nanoparticles for Highly Sensitive and Selective Ethanol Alarming.

Pure In2O3 nanoparticles are prepared by a facile precipitation method and are further modified by Ag. The synthesized samples are characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, Raman and UV-Vis spectra. The results show the successful heterojunction formation between Ag and In2O3. Gas sensing property measurements show that the 5 mol % Ag-modified In2O3 sensor has the response of 67 to 50 ppm ethanol, and fast response and recovery time of 22.3 and 11.7 s. The response is over one magnitude higher than that of pure In2O3, which can be attributed to the enhanced catalytic activity of Ag-modified In2O3 as compared with the pure one. The mechanism of the gas sensor can be explained by the spillover effect of Ag, which enhances the oxygen adsorption onto the surface of In2O3 and thus give rise to the higher activity and larger surface barrier height.

A simple large-scale synthesis of mesoporous In2O3 for gas sensing applications

In this paper, large-scale mesoporous In2O3 nanostructures were synthesized by a facile Lewis acid catalytic the furfural alcohol resin (FAR) template route for the high-yield. Their morphology and structure were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential thermal and thermogravimetry analysis (DSC-TG) and the Brunauer-Emmett-Teller (BET) approach. The as-obtained mesoporous In2O3 nanostructures possess excellent mesoporous and network structure, which increases the contact area with the gases, it is conducive for adsorption-desorption of gas on the surface of In2O3. The In2O3 particles and pores were both about 15nm and very uniform. In gas-sensing measurements with target gases, the gas sensor based on mesoporous In2O3 nanostructures showed a good response, short response-recovery time, good selectivity and stability to ethanol. These properties are due to the large specific surface area of mesoporous structure. This synthetic method could use as a new design concept for functional mesoporous nanomaterials and for mass production.

Small CeO2 clusters on the surface of semiconductor nanoparticles

Nanocomposite sensors containing CeO2 clusters on the surface of In2O3 and SnO2 crystals were synthesized. The structure of these systems was determined by Raman spectroscopy. In the CeO2 nanoclusters deposited on In2O3 crystals, the Ce-O vibration frequency was 462 cm−1 and did not depend on the CeO2 concentration. The Raman spectra of the clusters deposited on SnO2 crystals contained two peaks of Ce-O vibrations with frequencies of 462 and 470 cm−1. It was concluded that the peak at 470 cm−1 showed itself at low CeO2 concentrations in the composite (1–3 wt %) and its intensity quickly decreased as the CeO2 concentration increased; this peak was attributed to the CeO2 clusters that directly contact the SnO2 crystals and contain dissolved Sn+4. It was shown that when CeO2 was deposited on In2O3, the In+3 ions were not transferred into the deposited CeO2 clusters because of the difference between the charges and valences of the metal ions in the substrate and clusters; the mean size of the clusters was 9 nm. The relationship between the structure of the CeO2 nanoclusters and their influence on sensor effects was discussed.

Enhanced photoelectrochemical cathodic protection performance of the C3N4@In2O3 nanocomposite with quasi-shell–core structure under visible light

Carbon nitride@Indium oxide (C3N4@In2O3) composite with quasi-shell–core structure was successfully prepared in this work. The photoinduced open circuit potential and current density results show that the C3N4@In2O3 composite with quasi-shell–core structure could provide the optimal photoelectrochemical cathodic protection capability for 304 stainless steel under visible light when the adding amount of C3N4 in the C3N4@In2O3 composite is 3wt%. The light absorption capability of the C3N4@In2O3 composite was enhanced due to the synergistic effect of heterojunction structure. According to the HRTEM images, photoinduced Volt–Ampere characteristic curves and electrochemical impedance spectra, the ultrathin coating layer of C3N4 on the surface of In2O3 helps to form a heterojunction electric field at the interface between C3N4 and In2O3, which enhances the separation efficiency of the photogenerated electron–hole pairs. Excessive C3N4 will decline the photoelectrochemical cathodic protection of this composite due to the lower intrinsic electronic mobility and the lower photoelectric conversion property of C3N4.

First Combined Electron Paramagnetic Resonance and FT-IR Spectroscopic Evidence for Reversible O2Adsorption on In2O3–xNanoparticles

Adsorption-induced electronic property changes determine the performance of nanostructured transparent conductive oxides and sensor materials. For the study of O2 adsorption on electron rich In2O3–x nanoparticles we used transmission FT-IR spectroscopy in combination with electron paramagnetic resonance (EPR). The reversible emergence and annihilation of conduction band electrons is subject to O2 adsorption and was tracked at different oxygen pressures via IR active Drude absorptions. Corresponding results were related to EPR measurements that were performed under identical experimental conditions. For the first time we identified a weak adsorption complex between O2 and the surface of In2O3–x nanoparticles in the temperature range between T = 90 K and T = 298 K. Complementing and supporting our FT-IR observations, this evidence opens the way to study sensing relevant adsorption processes at room temperature with spectroscopy.

Synthesis of In2O3-graphene composites and their photocatalytic performance towards perfluorooctanoic acid decomposition

Perfluorooctanoic acid (PFOA) is an emerging persistent organic pollutant, which cannot be effectively decomposed by TiO2-base photocatalysis under mild condition. The In2O3-graphene composite was synthesized and its photocatalytic performance for PFOA decomposition was investigated. The graphene was enwrapped on the surface of In2O3 via a sonication-assisted solution route followed by heat treatment. The coverage of graphene on In2O3 was influenced by the calcination temperature. The In2O3 samples partially enwrapped by graphene showed enhanced activity for PFOA decomposition, while full coverage with graphene harm the photocatalytic activity of In2O3.

DFT Study of CO2Adsorption and Hydrogenation on the In2O3Surface

Catalytic conversion of CO2 to liquid fuels or valuable chemicals is an attractive alternative to geological sequestration. In the present study, we applied density functional theory slab calculations in the investigation of the adsorption and hydrogenation of CO2 on the (110) surface of In2O3. Our results indicate that the adsorbed CO2 is activated, forming a surface carbonate species by combining with surface oxygen, and has an adsorption energy of −1.25 eV. Heterolytic dissociative adsorption of H2 results in a surface hydroxyl from H binding the surface O site and a hydride from H binding the In site. The migration of H from the In site to the neighboring O site is energetically favorable but has a significant activation barrier of 1.32 eV. Water may adsorb on the surface either molecularly or dissociatively, with adsorption energy of −0.83 eV and −1.19 eV, respectively. Starting from CO2 coadsorbed with the H adatoms on the In2O3 surface, we examined two possible conversion pathways for CO2: (a) CO2 is hydrogenated by the H adatom on the In site to form a surface formate species (HCOO); (b) CO2 is protonated by the H adatom on the O site to form a surface bicarbonate species (COOH). Reaction a is endothermic by +0.33 eV, whereas b is exothermic by −0.78 eV. Although the formation of the bicarbonate species is energetically favorable, the subsequent step to form CO and OH is highly endothermic, with a reaction energy of +1.07 eV. Furthermore, the bicarbonate species can react with a surface hydroxyl easily, resulting in coadsorbed H2O and CO2. These results indicate that hydrogenation of CO2 to the formate species is favorable over protonation to the bicarbonate species on the In2O3 surface. These results are consistent with the experimental observations that the indium oxide based catalyst has a high CO2 selectivity and H2O resistance.

First-principles investigation of the electron work function for the (001) surface of indium oxide In2O3 and indium tin oxide (ITO) as a function of the surface oxidation level

The structure and properties of the (001) surface of indium oxide (In2O3) and indium tin oxide (ITO) are investigated theoretically. Ultrasoft pseudopotentials and the PBE exchange-correlation functional are used in our calculations. The calculated band structure of bulk In2O3, ITO, and their slabs with various surface oxidation levels are compared. Band structure features associated with surface states are detected. The dependence of the calculated electron work function for the In2O3 (001) and ITO (001) surfaces on the surface oxidation level is analyzed. It is found that the work function increases with the oxidation level of the surfaces.