In2O3 Nanoparticles Research Articles

NO2 gas sensing responses of In2O3 nanoparticles decorated on GO nanosheets

Nanomaterials offer a wide range of applications in environmental nanotechnology. Hazardous pollutants in the environment are needed to be detected and controlled effectively to avoid human health risks. In this paper, we described the fine-controlled growth of In2O3 nanoparticles embedded on GO nanosheets by a facile precipitation method. The In2O3@GO nanocomposites exhibited outstanding gas sensing performance as compared with pure In2O3 nanoparticles towards NO2. At 225 °C, the sensor displayed high selectivity, best response (78) to 40 ppm NO2, quick response, and recovery times of 106s/42s. The improved sensing performances of the nanocomposite were attributed to large surface area, high gas adsorption-desorption capability, and the formation of p-n heterojunctions between In2O3 nanoparticles and GO nanosheets. The excellent gas detecting activities validate In2O3@GO nanocomposites as a promising candidate in the NO2 gas sensor industry.

Anisotropic and hyperbranched InP nanocrystals via chemical transformation of in situ produced In2O3.

We synthesized indium phosphide (InP) nanoparticles of different shapes and sizes, utilizing triphenyl phosphite (TPOP) as the phosphorus source. We show that this reaction proceeds via the formation of in situ formed In2O3 nanoparticles followed by subsequent transformation with triphenyl TPOP acting as the phosphorus source. Our findings open up new synthetic possibilities utilizing a cost-effective, non-pyrophoric and non-toxic phosphorus precursor. The large surface area of hyperbranched InP NCs might be ideally suited for surface-driven processes such as catalysis and energy storage.

Controllable fabrication of hollow In2O3 nanoparticles by electron beam irradiation.

A growth strategy is presented for controllable fabrication of hollow In2O3 nanoparticles (NPs) via oxidation of In nanocrystals under electron beam irradiation. The morphology of the NPs can be tailored by changing the electron beam energy and current density. Yolk-shell NPs are preferentially formed under 200 keV electron beam irradiation, while hollow NPs are preferentially formed at 300 keV. This work confirms that electron beam irradiation is a valuable method for the engineering and modification of nanomaterials.

Layered Mxene Heterostructured with In2o3 Nanoparticles for Ammonia Sensors at Room Temperature

Layered Mxene Heterostructured with In2o3 Nanoparticles for Ammonia Sensors at Room Temperature

Magnetic behavior and site occupancy in Fe-doped In2O3 nanoparticles

(In1-xFex)2O3 monophasic nanoparticles were prepared by a freeze-drying process followed by heat treatment after which they were characterized by magnetization measurements and Mössbauer spectroscopy at temperatures ranging from 300 to 4.2 K. The iron cations were trivalent and substituted for the indium cations in both cationic sites, 24d and 8b, of the oxide matrix, showing an occupancy preference that depends on x. Two different magnetic regimes were observed after varying the temperature of the doped samples, and both correlated with the iron magnetic moments. At room temperature, the moments at the site 24d were partially ordered with ferromagnetic alignment, whereas those at the site 8b showed paramagnetic behavior. After decreasing the temperature, both sublattices become progressively ordered and more robustly below 50 K.

Tuning the structural, optical, and magnetic properties of In2O3 nanoparticles with an evaluation of its antibacterial efficiency via controlling the doping concentrations of Ni, Co, and Fe

The transition metal (TM) of Ni, Co and Fe- doped In2O3 nanoparticles (NixIn2−xO3, Cox In2−xO3 and FexIn2−xO3, where x = 0.00, 0.01, 0.03, 0.05, 0.07) have been synthesized successfully via sol-gel method. The crystalline pattern was studied by XRD. The spherical morphology of prepared samples was confirmed by TEM. Pristine In2O3 and Ni, Co, and Fe doped In2O3 nanocrystal exhibited a weak ferromagnetic nature at room temperature. Disc-diffusion antibiotic sensitivity test and pour plate technique were used to analyze the microbial growth in the presence of the prepared nanoparticles. The results indicated that the synthesized materials caused the higher inhibition for E. coli strains as compared to the S. aureus. Fe0.07 In 1.93O3 showed the highest inhibition rate. Based on our study, iron-doped In2O3 nanocrystal can be employed for restricting 95% of E. coli strains and 93% S. aureus and hence can find applications in the field of medicine.

Unraveling the Surface Hydroxyl Network on In2O3 Nanoparticles with High-Field Ultrafast Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy.

Hydroxyl groups are among the major active surface sites over metal oxides. However, their spectroscopic characterizations have been challenging due to limited resolutions, especially on hydroxyl-rich surfaces where strong hydroxyl networks are present. Here, using nanostructured In2O3 as an example, we show significantly enhanced discrimination of the surface hydroxyl groups, owing to the high-resolution 1H NMR spectra performed at a high magnetic field (18.8 T) and a fast magic angle spinning (MAS) of up to 60 kHz. A total of nine kinds of hydroxyl groups were distinguished and their assignments (μ1, μ2, and μ3) were further identified with the assistance of 17O NMR. The spatial distribution of these hydroxyl groups was further explored via two-dimensional (2D) 1H-1H homonuclear correlation experiments with which the complex surface hydroxyl network was unraveled at the atomic level. Moreover, the quantitative analysis of these hydroxyl groups with such high resolution enables further investigations into the physicochemical property and catalytic performance characterizations (in CO2 reduction) of these hydroxyl groups. This work provides insightful understanding on the surface structure/property of the In2O3 nanoparticles and, importantly, may prompt general applications of high-field ultrafast MAS NMR techniques in the study of hydroxyl-rich surfaces on other metal oxide materials.

Assembly of In2O3 nanoparticles decorated NiO nanosheets heterostructures and their enhanced gas sensing characteristics

In this work, a series of In2O3/NiO composites with hierarchical structure were prepared through an efficient synthesis method based on electrospinning technique and ion exchange reaction. Material characterization confirmed that the composite was composed by one-dimensionally aligned NiO nanosheets with In2O3 nanoparticles evenly attached to them. Gas sensing properties of the In2O3/NiO series composites were systematically investigated, accompanying with pristine NiO sample for comparison. An obvious enhancement in ethanol sensing performance was discovered for the NiO based sensor via decoration with In2O3 nanoparticles. The gas sensing mechanism of In2O3/NiO composite towards ethanol based on the formation of nanoscale p-n heterojunction structure was discussed. Besides, gas response properties of the In2O3/NiO series sensors to some harmful gases (including ethanol, DMF, acetone and ammonia) were found out to be highly dependent on the component content within the composites. The different gas sensing patterns of In2O3/NiO series sensors could be utilized to discriminate among these target gases.

Crystalline In2O3 nanoparticles synthesis using microwaves vaporization of metallic wires

Single crystal In2O3 nanoparticles were synthesized using microwaves vaporization of a thin metallic In wire in air. The output of an 800 W microwave generator was coupled through an antenna to a cylindrical wave guide cavity in with a metallic In wire was placed in the electromagnetic node, where a high power density was achieved. The wire strongly absorbed the microwaves, resulting in its heating, vaporization and finally a plasma plume formation. Optical emission spectroscopy investigations indicated that a high electronic temperature was reached in the plasma plume. The vaporized material was collected on a Si wafer placed near the cavity wall. Scanning electron microscopy investigations showed that the deposited material consisted of an agglomeration of In2O3 nanoparticles. X-ray diffraction and transmission electron microscopy (TEM) investigations indicated that the nanoparticles were very crystalline, with random orientation. X-ray photoelectron spectroscopy analysis confirmed the formation of stoichiometric In2O3. High resolution TEM investigations found that the deposited nanostructures were single crystals, with faceted surfaces. This simple method could have many applications for metal nanocrystal oxides synthesis.

Solvothermal synthesis and upconversion properties in Yb3+/Ln3+ (Ln3+=Er3+/ Ho3+/ Tm3+) codoped In2O3 nanoparticles with fine stability

Monodisperse In2O3: Yb3+/Er3+ upconverting nanoparticles (UCNPs) were firstly synthesized via solvothermal method in three-neck round-bottom flask. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR) methods are used to characterize the prepared UCNPs. The size of monodisperse spheroid nanoparticles prepared can be controllable in 31 nm. The sample exhibits stronger upconversion luminescence (UCL) than reported In2O3: Yb3+/Er3+ UCNPs with similar size. Furthermore, the obtained In2O3 UCNPs, by coating the SiO2 protecting layer, display fine stability. Simultaneously, the UCL properties and possible energy transfer process of In2O3: Yb3+/Ho3+ and In2O3: Yb3+/Tm3+ NPs have also been investigated by the spectra distribution and power dependence. The results indicate Yb3+/Er3+, Yb3+/Ho3+ and Yb3+/Tm3+ codoped In2O3 UCNPs is a probable oxide upconverting material with small size and intense UCL for biological applications.

Improved triethylamine sensing properties by designing an In2O3/ZnO heterojunction

Sensors of volatile organic compounds (VOCs) play a vital role in environmental monitoring. Although much progress has been made to develop new sensing materials, it remains challenging to detect a particular VOC selectively and without the interference of humidity. Herein, we report the effect of In2O3 nanoparticles on the VOC-sensing performance of ZnO twin-rods. The VOC-sensing tests were carried out in dry air and at a relative humidity (RH) of 26, 59, and 98%. The results indicated that the In2O3/ZnO heterostructure exhibited an improved sensing performance to triethylamine (TEA) compared to ZnO. In dry air, the responses to 100 ppm of TEA at 350 °C were 60.2 for the In2O3/ZnO heterostructure and 39.2 for pure ZnO. In2O3/ZnO even exhibited a high response of 6.2 to 1 ppm of TEA. Moreover, In2O3/ZnO exhibited a response to TEA up to 46.2 times higher than those of the other VOCs, indicating excellent selectivity. At 98% RH, the In2O3/ZnO heterostructure still had a high sensitivity to TEA, showing a response of 21.2 to 100 ppm of TEA with a response time of 1 s. The improved TEA-sensing performance of the In2O3/ZnO heterostructure can be attributed to the formation of the n-n heterojunction.

In-situ generation of In2O3 nanoparticles inside In[Co(CN)6] quasi-metal-organic-framework nanocubes for efficient electroreduction of CO2 to formate

Three-dimensional (3D) network structure of metal–organic framework (MOF) can accommodate outstanding electrocatalysis performances, but always collapse during the conversion to active materials or applications process. How to maintain the 3D network when producing active species is of great importance for full application of MOF. Herein, a new MOF material, In[Co(CN)6] (In-Co PBA) nanocubes, are firstly synthesized. Through a controlled low-temperature deligandation process, the In-Co PBA nanocubes are transformed to a novel In2O3@In-Co PBA quasi-MOF nanocubes, which basically retain the 3D porous structure of PBA but with in situ generated In2O3 nanoparticles inside. When used as CO2RR electrocatalyst, such a novel cubic composite structure exhibits excellent performances with faradaic efficiency of 85% for formate at a potential of −0.96 V and with current density of 31.5 mA·cm−2 at −1.32 V, surpassing most of the reported indium-based catalysts. The excellent performance can be attributed to the special composite structure, which provides not only active sites by In2O3 nanoparticles to catalyze CO2RR, but also the 3D porous framework by quasi-MOF to accelerate gaseous exchange and electrolyte permeation and prevent the electrode choking. This work offers a new strategy for the design of post-transition metal catalysts and the structure design of quasi-MOF.

Porous In2O3 thick films as a low temperature NO2 gas detector

In this work, porous indium oxide is synthesized by hydrothermal method. The In2O3 has been structurally and optically characterized by using XRD, XPS, FESEM and TEM techniques. The morphological studies have revealed the growth of self-assembled In2O3 nanoparticles which helpts to form a brick-like structure. The porous In2O3 nanoparticles have provided the large number of active sites for the adsorption of gas molecules which resulted in a quick sensor response of 6877 for 10 ppm of NO2 gas at very low temperature of 50 °C. Remarkably, the In2O3 sensor has shown the detection of NO2 gas down to 60 ppb.

Immobilization of In2O3 nanoparticles on the surface of reduced graphene oxide

This communication describes a new method for immobilizing indium oxide nanoparticles (∼20 nm) on the surface of reduced graphene oxide. Dispersion of graphene oxide with added In2O3 nanoparticles was treated in supercritical isopropanol, both a reducing agent of graphene oxide and a reaction medium. The resulting nanocomposite was characterized by different methods of physical and chemical analysis.

Rapid synthesis of rhombohedral In2O3 nanoparticles via a microwave-assisted hydrothermal pathway and their application for conductometric ethanol sensing

Rhombohedral In2O3 exhibits high gas sensing potential. However, its rapid synthesis remains challenging, and it is yet to be revealed whether it has a higher gas sensing capability than the cubic counterpart. Herein, we report a facile and rapid synthesis of rhombohedral In2O3 nanoparticles (NPs) via a microwave-assisted hydrothermal pathway, and compare their gas sensing characteristics with those of other In2O3 polymorphs (i.e., cubic NPs and mixed rhombohedral and cubic phases). To investigate the polymorphs for optimized gas sensing, the gas sensing properties of rhombohedral In2O3 NPs are compared with those of mixed-phase In2O3 NPs prepared via a conventional hydrothermal pathway and commercial cubic In2O3 NPs. The pure cubic In2O3 NPs and the mixed-phase In2O3 NPs show similar gas responses (resistance ratios) to 100 ppm ethanol in the temperature range of 150–400 °C. In contrast, the rhombohedral In2O3 NPs exhibit much higher ethanol responses at all the sensor temperatures. In particular, their ethanol response at 300 °C (43.1) is four times higher than the values obtained for the other polymorphic NPs (9.44–11.6) at the same temperature. Furthermore, the rhombohedral In2O3 NPs possess excellent ethanol selectivity with low cross-responses to 100 ppm NH3, CH4, H2, CO, CO2, and NO2 and long-term stable ethanol sensing properties for 21 days. The excellent gas sensing characteristics of rhombohedral In2O3 NPs are strongly related to their gas adsorption, particle sizes, and electrical conductivity. The rhombohedral In2O3 NPs can be potentially used in high-performance breathalyzers for screening drunk drivers.

Ultra-high ethanol sensitivity sensor based on porous In2O3 decorated with gold nanoparticles

Reasonable adjustment of the morphology and surface modification with precious metals are effective methods to improve gas sensitive properties. In this work, the gold-loaded mesoporous In2O3 nanoparticles were successfully synthesized through facile hydrothermal reaction and surface in situ reduction reaction in the absence of templates and surfactants. Microstructure and morphological characteristics of obtained gold-loaded mesoporous In2O3 nanoparticles were characterized by XRD, XPS, SEM and TEM. The characterization results revealed that the particle size of obtained gold-loaded In2O3 samples are between 50 and 150 nm, and the specific surface area is 31.9 m2/g. Many mesopores formed on the surface, and the pore size is concentrated in 14 nm. Through systematic gas sensing tests, we found that due to the electron sensitization and chemical sensitization of gold nanoparticles, the activation energy of the reaction is effectively reduced, the diffusion of adsorbed oxygen is accelerated and the content of vacancy oxygen and chemisorbed oxygen is significantly increased. The results presented that sensors based on gold-loaded mesoporous In2O3 showed ultra-high sensitivity to 100 ppm ethanol at the temperature of 220 °C, which is far superior to pure In2O3 materials. Operating temperature, response and recovery time, selectivity and stability are also relatively better. It is expected for gold-loaded In2O3 to become an ideal material for ethanol detection in the field of gas sensors.

ABCG1 and ABCG4 as key transporters in the development of pulmonary alveolar proteinosis by nanoparticles

Pulmonary alveolar proteinosis (PAP) has been reported in rodents treated with nanoparticles (NPs). However, little is known about the type of NPs producing PAP and their toxicity mechanisms. Here, we assembled seven PAP-inducing NPs and TiO2 NPs as a negative control. At 1 and 6 months after a single intratracheal instillation in rats, pulmonary inflammation and the gene expression of ATP-binding cassette (ABC) transporters and related genes were evaluated in separated alveolar macrophages (AMs). One month after intratracheal instillation, seven NPs (Eu2O3, In2O3, Pr6O11, Sm2O3, Tb4O7, and NiO) caused PAP, but only In2O3 NPs caused persistent PAP at 6 months after treatment. The levels of phospholipids, indicators of PAP, showed good correlations with the gene expression profile of five transporters (ABCA1, ABCB4, ABCB8, ABCG1, and ABCG4), which effluxing phospholipids in AMs. Among them, ABCG1 and ABCG4 might be key transporters involved in PAP development because both showed a negative correlation with the magnitude of PAP, while others might be compensatory transporters for PAP recovery, as they showed a positive correlation. In conclusion, the identification of seven PAP-producing NPs implies that PAP may be an emerging occupational disease and that ABCG1 and ABCG4 may be therapeutic targets for PAP.

Efficient Gradient Potential Top Electron Transport Structures Achieved by Combining an Oxide Family for Inverted Perovskite Solar Cells with High Efficiency and Stability.

Although inverted (p-i-n) structure perovskite solar cells (PSCs) have achieved high efficiency by commonly using fullerenes or their derivatives as electron transport layers (ETLs), the device stability and cost of fullerene materials are still of great concern. Herein, we demonstrate inorganic top ETLs simply composed from a family of metal oxides including In2O3 and its derivative of Sn:In2O3 with a gradient potential structure. For inverted PSCs, the typical film formation process of In2O3 will damage or degrade perovskite materials underneath; thus, we report a low temperature synthesis approach for obtaining In2O3 and Sn:In2O3 nanoparticles that can form effective top ETLs without any post-treatment. The one-family oxide-based top ETL features with the enhanced built-in potential, high electron extraction, and low interfacial recombination, offering a power conversion efficiency (PCE) of 20.65% in PSCs constructed from oxide-only carrier (both hole and electron) transport layers (CTLs), which is the highest efficiency in oxide-only CTL-based inverted PSCs to the best of our knowledge. Equally important, the inverted PSCs based on the Sn:In2O3/In2O3 ETL show the excellent operational stability and remain 90% of the initial value of PCE over 2000 h. Consequently, this work contributes to the robust strategy of all oxide-only CTLs in developing rigid and flexible PSCs for practical photovoltaic applications.

The Effect of Noble Metals on Co Gas Sensing Properties of In2O3 Nanoparticles

Three types of In2O3 nanoparticles decorated with Au, Pd and Pt nanoparticles, respectively, were synthesized by thermal decomposition method, and the effects of metal nanoparticles on their phase, microstructure, chemical state, carrier types were investigated with XRD, SEM/TEM, and XPS. Additionally, sensing properties to CO gas, such as sensitivity, etc., were examined with sensing apparatus. Au-decorated In2O3 nanoparticles exhibited the highest sensitivity to CO gas, with S = 5.59 at a 10 ppm CO gas concentration at 50 °C compared to Pd or Pt-decorated In2O3 nanoparticles. This can be interpreted as a much higher adsorption of oxygen molecules on the In2O3 surface due to the high oxygen vacancies in the In2O3 lattice, which generates an electron depletion region in the outer layer of In2O3 to sharply increase the resistance or the spill-over effect due to Au nanoparticles on In2O3. Au nanoparticles were observed in the TEM images and confirmed by XPS analysis.

In situ tailoring the morphology of In(OH)3 nanostructures via surfactants during anodization and their transformation into In2O3 nanoparticles

The present work reports the effect of various surfactants on the morphology of In(OH)3 nanostructures prepared via anodization. In-sheets were anodized in an environmentally benign electrolyte containing a small quantity of CTAB, CTAC, and PDDA surfactants at room temperature. The produced nanostructures were characterized using XRD, HRTEM, SAED, and EDAX. The morphology of indium hydroxide (In(OH)3) nanostructures was successfully tailored in situ with the help of surfactants in 1 M KCl aqueous electrolyte. XRD results confirmed the formation of In(OH)3 and indium oxyhydroxide (InOOH) nanostructures in the pristine form which were transformed into single-phase cubic In2O3 nanoparticles (NPs) after calcination. HRTEM analyses showed that the morphology and size of the In(OH)3 nanostructures can be tuned to form nanorods, nanosheets and nanostrips using different surfactants. The results revealed that CTAC and PDDA surfactants have a profound effect on the morphology of In(OH)3 nanostructure compared to CTAB due to the higher concentration of Cl− ion. The possible mechanism of surfactants effect on the morphology is proposed. Furthermore, annealing converted the In(OH)3 nanostructures into spherical In2O3 NPs with uniform and homogeneous size. We anticipate that the morphology of other metal-oxides nanostructure can be tuned using this simple, facile and rapid technique. In2O3 NPs prepared without and with CTAB surfactant were further explored for the non-enzymatic detection of hydrogen peroxide (H2O2). Electrochemical measurements showed enhanced electrocatalytic performance with fast electron transfer (∼2s) between the redox centers of H2O2 and electrode surface. The In2O3 NPs prepared using CTAB/Au electrode exhibited about 4-fold increase in sensitivity compared to the bare Au electrode. The biosensor also demonstrated good reproducibility, higher selectivity, and increased shelf life.