rh-In2O3 Nanoparticles for Efficient Photocatalytic Degradation of Rifampin

Photodegradation, a widely accepted and promising technology, has gained significant attention for addressing the escalating concerns of environmental deterioration. In this article, rhombohedral corundum-type In2O3 nanocrystals were obtained from the transformation of InOOH via a simple calcining process. Under ultraviolet light irradiation, they showed higher photocatalytic activity in the decomposition of rifampin compared to that of the cubic phase In2O3 and P25-TiO2. Furthermore, the probable pathway and the feasible mechanism for the degradation of rifampin were also deeply explored and discussed.

Construction of organic-inorganic "chelate" adsorption sites on metal oxide semiconductor for room temperature NO2 sensing

Metal oxide semiconductors (MOS) have been extensively studied for gas sensing due to their excellent chemical stability and adjustable electronic properties. However, there is still a lack of ingenious design strategies to achieve customizable gas detection in complex environments. Herein, a novel and scalable strategy of constructing organic-inorganic "chelate" adsorption sites is proposed to promote the affinity of MOS sensing materials to target molecules. Specifically, 3-aminopropyltriethoxysilane (APTES)-functionalized reduced graphene oxide (rGO) was decorated on In₂O₃ tubes (AG/In_x), and its NO₂ sensing performance was studied. As a result, the optimal AG/In_x shows boosted room-temperature NO₂ response, and its response to 1 ppm NO₂ is 4.8 times that of In₂O₃. More attractively, the optimal AG/In_x exhibits good selectivity, as well as outstanding detection ability (R_g/R_a = 1.6) for low concentration NO₂ (20 ppb). Experimental results suggest that APTES-rGO not only acts as the electron acceptor to accelerate charge transfer, but also enhances NO₂ adsorption. Further theoretical calculations reveal that NO₂ is simultaneously adsorbed at rGO and APTES via a flexible "chelate" mechanism. The multidentate adsorption configuration remarkably strengthens the NO₂-host interaction, which is conducive to improving sensing performance. This work may inspire the material design of a new generation high-performance gas sensors.

Metal Oxide Chemiresistors: A Structural and Functional Comparison between Nanowires and Nanoparticles

Metal oxide nanowires have become popular materials in gas sensing, and more generally in the field of electronic and optoelectronic devices. This is thanks to their unique structural and morphological features, namely their single-crystalline structure, their nano-sized diameter and their highly anisotropic shape, i.e., a large length-to-diameter aspect ratio. About twenty years have passed since the first publication proposing their suitability for gas sensors, and a rapidly increasing number of papers addressing the understanding and the exploitation of these materials in chemosensing have been published. Considering the remarkable progress achieved so far, the present paper aims at reviewing these results, emphasizing the comparison with state-of-the-art nanoparticle-based materials. The goal is to highlight, wherever possible, how results may be related to the particular features of one or the other morphology, what is effectively unique to nanowires and what can be obtained by both. Transduction, receptor and utility-factor functions, doping, and the addition of inorganic and organic coatings will be discussed on the basis of the structural and morphological features that have stimulated this field of research since its early stage.

Printable Single-Unit-Cell-Thick Transparent Zinc-Doped Indium Oxides with Efficient Electron Transport Properties

Ultrathin transparent conductive oxides (TCOs) are emerging candidates for next-generation transparent electronics. Indium oxide (In₂O₃) incorporated with post-transition-metal ions (e.g., Sn) has been widely studied due to their excellent optical transparency and electrical conductivity. However, their electron transport properties are deteriorated at the ultrathin two-dimensional (2D) morphology compared to that of intrinsic In₂O₃. Here, we explore the domain of transition-metal dopants in ultrathin In₂O₃ with the thicknesses down to the single-unit-cell limit, which is realized in a large area using a low-temperature liquid metal printing technique. Zn dopant is selected as a representative to incorporate into the In₂O₃ rhombohedral crystal framework, which results in the gradual transition of the host to quasimetallic. While the optical transmittance is maintained above 98%, an electron field-effect mobility of up to 87 cm² V^-1 s^-1 and a considerable sub-kΩ^-1 cm^-1 ranged electrical conductivity are achieved when the Zn doping level is optimized, which are in a combination significantly improved compared to those of reported ultrathin TCOs. This work presents various opportunities for developing high-performance flexible transparent electronics based on emerging ultrathin TCO candidates.

Regulation of electronic properties of ZnO/In2O3 heterospheres via atomic layer deposition for high performance NO2 detection

Heterogeneous In₂O₃/ZnO spheres designed by atomic layer deposition manifest high response to NO₂ detection.

Sr-Doped Cubic In2O3/Rhombohedral In2O3 Homojunction Nanowires for Highly Sensitive and Selective Breath Ethanol Sensing: Experiment and DFT Simulation Studies

In recent years, it is urgent and challenging to fabricate highly sensitive and selective gas sensors for breath analyses. In this work, Sr-doped cubic In₂O₃/rhombohedral In₂O₃ homojunction nanowires (NWs) are synthesized by one-step electrospun technology. The Sr doping alters the cubic phase of pure In₂O₃ into the rhombohedral phase, which is verified by the high-resolution transmittance electron microscopy, X-ray diffraction, and Raman spectroscopy, and is attributable to the low cohesive energy as calculated by the density functional theory (DFT). As a proof-of-concept of fatty liver biomarker sensing, ethanol sensors are fabricated using the electrospun In₂O₃ NWs. The results show that 8 wt % Sr-doped In₂O₃ shows the highest ethanol sensing performance with a high response of 21-1 ppm, a high selectivity over other interfering gases such as methanol, acetone, formaldehyde, toluene, xylene, and benzene, a high stability measured in 6 weeks, and also a high resistance to high humidity of 80%. The outstanding ethanol sensing performance is attributable to the enhanced ethanol adsorption by Sr doping as calculated by DFT, the stable rhombohedral phase and the preferred (104) facet exposure, and the formed homojunctions favoring the electron transfer. All these results show the effective structural modification of In₂O₃ by Sr doping, and also the great potency of the homojunction Sr-doped In₂O₃ NWs for highly sensitive, selective, and stable breath ethanol sensing.

A novel rGO-decorated ZnO/BiVO4 heterojunction for the enhancement of NO2 sensing properties

A novel ZnO/BiVO₄/rGO composite exhibits excellent gas sensing performance, which is attributed to the formation of n–n heterojunctions and decoration with rGO.

Joint Theoretical and Experimental Study on the La Doping Process in In2O3: Phase Transition and Electrocatalytic Activity

In₂O₃ and La³⁺-doped In₂O₃ nanostructures were synthesized through a facile and fast chemical route based on the microwave-assisted hydrothermal method combined with rapid thermal treatment in a microwave oven. The presence of the La³⁺ doping process modifies the size and morphology of the In₂O₃ nanostructures and also stabilizes the rhombohedral (rh) In₂O₃ phase with respect to the most stable cubic (bcc) polymorph. X-ray diffraction (XRD) patterns and Rietveld refinements, Raman, UV-vis, and energy dispersive X-ray (EDX) spectroscopies, transmission electron (TEM) and field-emission scanning electron (FE-SEM) microscopies, as well as PL emissions have been performed. To complement and rationalize the experimental results, first-principle calculations, based on density functional theory, are carried out to obtain the formation energies of the In₂O₃ and bcc- and rh-In₂O₃-doped phases, their geometry and electronic properties. Theoretical results are able to explain the relative stabilization of the rh-phase with respect to the bcc-phase based on the analysis geometry changes and the electronic redistribution induced by the La³⁺ doping process. In addition, Wulff construction is employed to match the theoretical and experimental morphologies of the cubic phase. The synthesized samples were applied for the O₂ evolution reaction (OER). The La³⁺-doped In₂O₃ film presents superior electrocatalytic activity, with an onset potential lower than the undoped In₂O₃ film that can be associated with the increase in electron density caused by the La³⁺ doping process. This study provides a versatile strategy for obtaining In₂O₃ and La³⁺-doped In₂O₃ nanostructures for practical applications.

Synthesis of self-assembled mesoporous 3D In2O3 hierarchical micro flowers composed of nanosheets and their electrochemical properties

This report describes the methodology for the fabrication of mesoporous In₂O₃ microflowers by hydrothermal and calcination procedures in which In(OH)₃/In₂S₃ acts as an intermediate. Both In₂O₃ and its precursor were analyzed with scanning electron microscopy, energy dispersive X-ray spectrophotometry, transmission electron microscopy and powder X-ray diffraction. BET surface area, pore size and pore volume analyses were also carried out. Electron microscopy images clearly evidence the self-assembly of 2D nanosheets into the micro flower structure. The mechanism of self-assembly and calcination is reported. Electrochemical properties of the synthesized In₂O₃ micro flowers were studied.

This report describes the methodology for the fabrication of mesoporous In₂O₃ microflowers by hydrothermal and calcination procedures in which In(OH)₃/In₂S₃ acts as an intermediate.

Flower-like In2O3 modified by reduced graphene oxide sheets serving as a highly sensitive gas sensor for trace NO2 detection

In this work, we described gas sensors based on the materials composed of hierarchical flower-likeIn₂O₃ and reduced graphene oxide (rGO), which were fabricated by a facile one-step hydrothermal method. The rGO-In₂O₃ composites exhibited enhanced sensing performance towards NO₂ through comparison with the pure In₂O₃ sample. The operating temperature can be tuned by the percentage of rGO in the composites. The sensor based on 5wt% rGO-In₂O₃ could work at room temperature with a high response value to 1ppm NO₂. 3wt% rGO-In₂O₃ composite was adopted for the ultra-sensitivity gas sensor owing to its extremely low limit of detection of 10ppb with rapid response time to NO₂. The sensor also exhibited excellent selectivity and stability. The ultra-sensitivity of rGO-In₂O₃ should be related to synergistic effect of the hierarchical structure of In₂O₃ and the presence of rGO in the composites, which provided enhanced surface area and local p-n heterojunctions in rGO/In₂O₃ composites.

Hydrothermal synthesis and Cl2 sensing performance of porous-sheets-like In2O3 structures with phase transformation

Phase transformation (bcc-In₂O₃ to rh-In₂O₃) and high Cl₂ sensing performance of Fe doped porous-sheets-like In₂O₃.

An In2O3 nanorod-decorated reduced graphene oxide composite as a high-response NOx gas sensor at room temperature

An In₂O₃ nanorod-decorated reduced graphene oxide composite has been successfully synthesized, and this composite shows a good response, fast response time to NO_x with good selectivity and low detection limit at room temperature.

Facile synthesis of nanoparticle packed In2O3 nanospheres for highly sensitive NO2 sensing

Nanoparticle packed In₂O₃ nanospheres are successfully synthesized via a facile one-step solvothermal method followed by annealing.

One-step hydrothermal preparation of Ce-doped MoO3 nanobelts with enhanced gas sensing properties

Rare earth ions are considered as the ideal dopants to modify the crystal structure, electronics structure, and gas sensing performance of metal oxides semiconductors.

Highly active and porous single-crystal In2O3 nanosheet for NOx gas sensor with excellent response at room temperature

Porous single-crystal In₂O₃ nanosheet was well-designed and prepared through calcination after liquid reflux, then exhibited a distinguished response, fast response time to NOx with good selectivity and low detection limit at room temperature.

Corundum type indium oxide nanostructures: ambient pressure synthesis from InOOH, and optical and photocatalytic properties

A simple, cost effective, surfactant free and scalable synthesis of rh-In₂O₃ nanostructures showing intense blue light emission has been developed under ambient pressure.

Synthesis and NO2 sensing properties of indium oxide nanorod clusters via a simple solvothermal route

In this work, a low-cost and environmentally friendly solvothermal route to the synthesis of indium oxide nanorod clusters was described in the presence of sodium chlorate and urea.

Facile synthesis and gas-sensing performance of Sr- or Fe-doped In2O3 hollow sub-microspheres

Sr- or Fe-doped In₂O₃ hollow sub-microspheres were successfully fabricated, which show excellent gas sensing performance towards a series of organic solvents.

Si doped highly crystalline mesoporous In2O3 nanowires: synthesis, characterization and ultra-high response to NOx at room temperature

The synthesized INW-2 has an ultrathin surface layer and high density defects. The special structure offers available active centers for gas/surface reactions. INW-2 sensor possesses the ultrahigh response and selectivity to NOx at room temperature.

3D porous α-Ni(OH)2 nanostructure interconnected with carbon black as a high-performance gas sensing material for NO2 at room temperature

The 3D porous α-Ni(OH)₂/carbon black nanostructure composites were fabricated via a simple refluxing method using SDBS as the template. The composites exhibited excellent sensing properties with fast response and low detection limit of NO₂ at room temperature.