ITO Nanoparticles Research Articles

Decorating carbon nanotubes with nanoparticles of indium tin oxide for the voltammetric determination of metaproterenol

Abstract A voltammetric sensor prepared using a composite of multi-walled carbon nanotubes (MWCNTs) and indium tin oxide nanoparticles (ITONPs) were applied for quantifying metaproterenol in pharmaceuticals and urine samples. The characterization of the composite layer was performed using energy dispersive X-ray and scanning electron microscopic techniques. ITONPs/MWCNTs/GCE exhibited a great electrocatalytic effect towards the oxidation of metaproterenol with a well-defined peak at 550 mV. Compared with a number of electrodes, a GCE decorated with both MWCNTs and ITO nanoparticles also exhibited a large enhancement of voltammetric response for metaproterenol. In addition, the higher concentration of uric acid (UA) does not interfere with the selective quantification of metaproterenol. Differential pulse voltammetry (DPV) was performed for the determination of metaproterenol at ITONPs/MWCNTs/GCE. A linear plot yielding a detection limit of 1.2 × 10 − 8 M was obtained for current responses of metaproterenol against concentrations in the range of 3.0 × 10 − 8 –2.2 × 10 − 5 M. The proposed modified electrode provided better voltammetric behavior, good reproducibility and long-time stability. The selective quantification of metaproterenol makes the proposed electrode of great interest for both monitoring its therapeutic use and for doping analysis.

Effect of hybrid nanoinks on solution-based Sn-doped In2O3 films under low-temperature microwave annealing

Solution-based Sn-doped In2O3 (ITO) films were fabricated using well-dispersed hybrid ITO nanoinks, which consisted of high-crystalline ITO nanoparticles and ITO sols, by combining the methods of spin-coating and low-temperature microwave annealing. To investigate the optimum conditions for the hybrid ITO nanoinks, we used four different weight ratios of ITO nanoparticles to ITO sols in the hybrid nanoinks: 0 (sample A), 0.06 (sample B), 0.12 (sample C), and 0.24 (sample D). Sample D exhibited superior sheet resistance (~131.3Ω/□), , good transmittance (~87.2%), and excellent figure of merit (~19.3×10−4Ω−1) when compared to the other samples. This improvement performance is due to the improved densification of the solution-based ITO films, where the optimum amount of ITO sols in the films served as a smooth medium that linked the high-crystalline ITO nanoparticles. Therefore, our study can offer a novel strategy that can be applied to flexible transparent conducting films (TCFs) as well as to the low-cost fabrication of high-performance TCFs in various optoelectronic applications.

Electron transport within transparent assemblies of tin-doped indium oxide colloidal nanocrystals

Stripe-like compact assemblies of tin-doped indium oxide (ITO) colloidal nanocrystals (NCs) are fabricated by stop-and-go convective self-assembly (CSA). Systematic evaluation of the electron transport mechanisms in these systems is carried out by varying the length of carboxylate ligands protecting the NCs: butanoate (C4), octanoate (C8) and oleate (C18). The interparticle edge-to-edge distance L0, along with a number of carbon atoms in the alkyl chain of the coating ligand, are deduced from small-angle x-ray scattering (SAXS) measurements and exhibit a linear relationship with a slope of 0.11 nm per carbon pair unit. Temperature-dependent resistance characteristics are analyzed using several electron transport models: Efros–Shklovskii variable range hopping (ES-VRH), inelastic cotunneling (IC), regular island array and percolation. The analysis indicated that the first two models (ES-VRH and IC) fail to explain the observed behavior, and that only simple activated transport takes place in these systems under the experimental conditions studied (T = 300 K to 77 K). Related transport parameters were then extracted using the regular island array and percolation models. The effective tunneling decay constant βeff of the ligands and the Coulomb charging energy EC are found to be around 5.5 nm−1 and 25 meV, respectively, irrespective of ligand lengths. The theoretical tunneling decay constant β calculated using the percolation model is in the range 9 nm−1. Electromechanical tests on the ITO nanoparticle assemblies indicate that their sensitivities are as high as ∼30 and remain the same regardless of ligand lengths, which is in agreement with the constant effective βeff extracted from regular island array and percolation models.

Development of NO2 gas sensor using Sn-doped ITO nanoparticles prepared by Sol-Gel method

Development of NO2 gas sensor using Sn-doped ITO nanoparticles prepared by Sol-Gel method

Facile transfer fabrication of transparent, conductive and flexible In2O3:Sn (ITO) nanowire arrays electrode via selective wet-etching ZnO sacrificial layer

We report a facile transfer fabrication of tin-doped indium oxide (In2O3:Sn) nanowires array (ITO NWs) electrode with high transparency and bending stability via selective wet-etching of a sacrificial ZnO layer. The ITO NWs are grown on ZnO (200nm)/Si substrate by using a vapor-liquid-solid (VLS) method and then subsequently it is soaked in basic solution (1M NaOH) to dissolve ZnO under-layer selectively, which enables to detach the ITO NWs electrode from the substrate without damage. We found that open-structure and porous nature of the ITO NWs with ITO nanoparticles support facilitate the NaOH solution penetration into the ZnO layer, thus enabling rapid peeling off the ITO NWs, even for a large sized substrate. The fabricated ITO NWs electrode on the PET substrate showed good transparency, conductivity and flexibility, eventually enabling to fabricate a flexible solid-state dye-sensitized solar cell with a satisfactory performance.

Manufacturing of Low Catalyst Loading PEM Electrolyzer Meas Using Reactive Spray Deposition Technology

Proton exchange membrane (PEM) water electrolysis is a low temperature, low carbon footprint technology for the production of high purity hydrogen. PEM electrolyzers can operate at higher current densities and higher pressures with lower gas crossover and a more compact physical footprint than other water electrolysis processes such as alkaline electrolyzers and solid oxide electrolyzers. However, PEM electrolyzers require expensive, noble metal catalysts and a considerable effort is currently underway to minimize catalyst loading to reduce cost, which crucial for the penetration of PEM electrolysis technology into the market. [1] Ir or IrO2 is generally recognized as the state-of-the-art electrocatalyst for oxygen evolution reaction (OER) at the anode, while Pt remains the best candidate for the hydrogen evolution reaction (HER) at the cathode [1,2]. The catalyst loading on the cathode is typically at least 0.5-1.0 mg/cm2, whereas the anode catalyst loading is around 2 mg/cm2[1]. Reactive spray deposition technology (RSDT) has proven to be a cost-effective method for producing high performance PEM electrolyzer membrane electrode assemblies (MEAs) [3,4]. RSDT is a flame-based method that combines catalyst synthesis and processing in a single step and has the flexibility in optimizing the catalyst composition, making gradient and other complex structures possible. This has allowed our team to reduce the cathode Pt loading below 0.2 mg/cm2with enhanced performance compared to the standard baseline(Figure 1 a). Xu and Scott studied the effect of ionomer content in the catalyst layer on PEM electrolysis using decal transfer method and the optimum ionomer content for cathode was found to be 20% [5]. However, at such low Pt loading, we found that the catalyst layer structure and ionomer content becomes more important than catalyst loading, meaning that each catalyst formulation needs to be carefully controlled. Since RSDT is a dry deposition process, the catalyst layer formation mechanism can be different from catalyst-ink spraying and drying process. Therefore, in this talk we will focus on the role of the catalyst layer pore structure and I/C ratio in dictating the performance of RSDT-derived PEM electrolyzer MEAs. Studies on ITO as fuel cell [6-7] or electrolysis catalyst [8] support have shown good stability above 1.4V and high performance. Recent work has also shown the feasibility of using RSDT to directly deposit both ITO-supported and unsupported Ir/IrO2 with ~0.1 mg/cm2 Ir loading and initial MEA performance close to the baseline. Figure 1 c shows the TEM micrograph of Ir/IrO2particles supported on ITO. The processing variables being explored to achieve stable and high performance with low Ir loading will be discussed. Figure 1. a)PEM electrolyzer performance using RSDT fabricated Pt/C as cathode and Ir/IrO2; b) electrolyzer performance using RSDT fabricated Ir/IrO2 supported on ITO as anode and Pt/C as cathode; c) TEM micrograph of Ir/IrO2supported on ITO nanoparticles

Highly selective ppb-level detection of NH3 and NO2 gas using patterned porous channels of ITO nanoparticles

We demonstrate the formation of micro-patterned porous electronic channels of tin-doped indium oxide nanoparticles (ITO NPs) and their utilization as sensor transducers for the detection of NH3 and NO2 gas in air. The ITO NP channels were formed by dipping a molecularly patterned solid substrate into an ITO NP suspension and then pulling it vertically at a precisely controlled speed. The ITO NPs were self-assembled on the intended regions with high definition, as the NPs were selectively adsorbed on the polar SiO2 regions avoiding the nonpolar regions. The thickness of the assembled ITO NP patterns could be modulated by controlling the pulling speed. The NPs formed a dense percolated network through which current could flow without any post-treatment such as heat annealing. By forming electrodes on the assembled ITO NP patterns, we fabricated sensor transducers for the detection of ammonia and nitrogen dioxide. The sensor showed a highly sensitive detection of NH3 and NO2 gas down to ppb-level. Furthermore, the sensor response changed in opposite direction to reducing NH3 and oxidizing NO2 gases, which shows that our sensor can be utilized in the selective detection of NH3 and NO2.

Application of Degenerately Doped Metal Oxides in the Study of Photoinduced Interfacial Electron Transfer.

Degenerately doped In2O3:Sn semiconductor nanoparticles (nanoITO) have been used to study the photoinduced interfacial electron-transfer reactivity of surface-bound [Ru(II)(bpy)2(4,4'-(PO3H2)2-bpy)](2+) (RuP(2+)) molecules as a function of driving force over a range of 1.8 eV. The metallic properties of the ITO nanoparticles, present within an interconnected mesoporous film, allowed for the driving force to be tuned by controlling their Fermi level with an external bias while their optical transparency allowed for transient absorption spectroscopy to be used to monitor electron-transfer kinetics. Photoinduced electron transfer from excited-state -RuP(2+*) molecules to nanoITO was found to be dependent on applied bias and competitive with nonradiative energy transfer to nanoITO. Back electron transfer from nanoITO to oxidized -RuP(3+) was also dependent on the applied bias but without complication from inter- or intraparticle electron diffusion in the oxide nanoparticles. Analysis of the electron injection kinetics as a function of driving force using Marcus-Gerischer theory resulted in an experimental estimate of the reorganization energy for the excited-state -RuP(3+/2+*) redox couple of λ* = 0.83 eV and an electronic coupling matrix element, arising from electronic wave function overlap between the donor orbital in the molecule and the acceptor orbital(s) in the nanoITO electrode, of Hab = 20-45 cm(-1). Similar analysis of the back electron-transfer kinetics yielded λ = 0.56 eV for the ground-state -RuP(3+/2+) redox couple and Hab = 2-4 cm(-1). The use of these wide band gap, degenerately doped materials provides a unique experimental approach for investigating single-site electron transfer at the surface of oxide nanoparticles.

Oxygen electroreduction promoted by quasi oxygen vacancies in metal oxide nanoparticles prepared by photoinduced chlorine doping.

Quasi oxygen-deficient indium tin oxide nanoparticles (ITO NPs) were prepared by photoinduced chlorine doping, and exhibited much enhanced electrocatalytic activity for oxygen reduction reaction (ORR) in alkaline media, as compared with pristine ITO.

Tunable morphologies of indium tin oxide nanostructures using nanocellulose templates

Nanocellulose fibrils have been used as sacrificial templates for synthesizing ITO nanoparticles with controllable morphology.

Heat generation characteristics of microheaters prepared with ITO nanoparticles and organic additives

In this study, we demonstrate the heat generation characteristics of microheaters prepared with an ITO nanoparticle (NP) paste, which is a mixture of ITO NPs, polymethyl methacrylate, and terpineol. A comparison with microheaters prepared with ITO NPs only shows that the organic additives substantially enhance their heat generation characteristics. The maximal temperature obtained is 445°C at a bias voltage of 12V, which is three times higher than for the NP microheaters. Moreover, the NP-paste microheaters have better thermal stability and a more uniform heating zone. The enhancement in the heat generation characteristics results from the smoother surfaces and the higher density of the NP-paste films.

Enhanced charge collection in dye-sensitized solar cells utilizing collector–shell electrodes

Nanostructured porous tin-doped indium oxide (ITO) films were prepared by screen printing of an ITO nanoparticle paste onto conducting fluorine-doped tin oxide (FTO) substrates. The ITO films were subsequently coated with thin layers of TiO2 by the hydrolysis of TiCl4 to form the collector–shell photoelectrodes. The morphology of films was analysed by scanning electron microscope (SEM). It was found that a uniform coating of TiO2 was achieved when three or more deposition cycles were applied. Dye-sensitized solar cells were constructed with the collector–shell photoelectrodes using an electrolyte containing the [Co(bpy)3]2+/3+ (bpy = 2,2′-bipyridine) redox couple and MK-2, an organic sensitizer and efficiencies of 3.3% achieved. Charge transport in cells utilizing the collector–shell electrodes was found to be 2–6 times faster than those utilizing P25-based TiO2 electrodes.

Generation of phase-only holograms by laser ablation of nanoparticulate ITO layers

Phase holograms offer great potential e.g. for laser beam shaping and imaging applications. However, the generation of these structures typically requires multi-step processes which tend to be time-consuming and expensive, especially if high-quality structures are required. In this work we demonstrate a flexible and inexpensive method which allows for the production of binary phase-only holograms by laser ablation of ITO nanoparticle layers. Since these layers are ablated free of residues, accurately defined phase shifts can be achieved. While arbitrarily shaped structures can be generated, the ITO layer thickness can be adjusted in order to freely tune the phase shift for the desired wavelength. In the diffraction patterns generated by the holograms we observed an excellent zero order suppression.

Plannar light source using a phosphor screen with single-walled carbon nanotubes as field emitters.

We developed and successfully fabricated a plannar light source device using a phosphor screen with single-walled carbon nanotubes (SWCNTs) as field emitters in a simple diode structure composed of the cathode containing the highly purified and crystalline SWCNTs dispersed into an organic In2O3-SnO2 precursor solution and a non-ionic surfactant. The cathode was activated by scratching process with sandpaper to obtain a large field emission current with low power consumption. The nicks by scratching were treated with Fourier analysis to determine the periodicity of the surface morphology and designed with controlling the count number of sandpapers. The anode, on the other hand, was made with phosphor deliberately optimized by coverage of ITO nanoparticles and assembled together with the cathode by the new stable assembling process resulting to stand-alone flat plane-emission panel. The device in a diode structure has a low driving voltage and good brightness homogeneity in that plane. Furthermore, field emission current fluctuation, which is an important factor in comparing luminance devices too, has a good stability in a simple diode panel. The flat plane-emission device employing the highly purified and crystalline SWCNTs has the potential to provide a new approach to lighting in our life style.

Effect of pyrolysis temperature on the electrical, optical, structural, and morphological properties of ITO thin films prepared by a sol–gel spin coating process

Tin doped indium oxide (ITO) thin films were fabricated by sol–gel spin coating (S–G-S) method with In(NO3)3·H2O and SnCl4 as indium and tin precursors, respectively. Polyvinylalcohol (PVA) was used for synthesis of ITO sol as a stabilizer and binder. The influence of different pyrolysis temperatures after each coating on the electrical, optical, structural, and morphological properties of the films were characterized by means of four point probe, UV–Vis, FT-IR spectroscopy, X-ray diffraction and scanning electron microscopy (SEM). Then the prepared thin films were annealed in the temperature of 550°C under argon atmosphere (the rate of 100mL/min and the pressure of 10Torr). The obtained results indicate that minimum resistivity of 12.5×10−4Ωcm and optical transmittance of more than 83% in the UV–Vis region with a band gap of 3.84eV were achieved for the films pyrolyzed at 500°C for 30min. X-ray diffraction analysis confirmed the formation of cubic bixbyite structure of indium oxide by the main peak of the (222) plane. The grain size of ITO nanoparticles was obtained about 25–50nm and the thickness of the film was investigated by SEM surface images and cross-section images, respectively and the effect of Burstein-Moss on optical band gap of sample was discussed too.

Surface Modification of ITO Nanoparticles by Trimesic Acid: A Combined Experimental and DFT Study

Surface modification of ITO films is important for their applications in optoelectronics. Herein, trimesic acid was used to modify polycrystalline ITO nanoparticles. Spectroscopic results indicate the formation of carboxylate on the ITO nanoparticle surfaces upon modification. Density functional theory calculations reveal an upstanding adsorption structure of the acid molecule on the ITO (111) surface and the formation of a carboxylate surface species. The dissociative chemisorption of trimesic acid on the selected surface was found to be thermodynamically exothermic and kinetically facile. We show that the surface-modified ITO nanoparticles are capable of effectively enhancing the charge-transfer rate and substantially boosting electrocatalytic effect toward redox of ferrocene via a π–π interaction between ferrocene and the adsorbate.

Synergetic effect of LaB6 and ITO nanoparticles on optical properties and thermal stability of poly(vinylbutyral) nanocomposite films

In this work, different compositions of lanthanum hexaboride (LaB6) and tin-doped indium oxide (ITO) nanoparticles were doped into poly(vinylbutyral) (PVB) matrix to prepare PVB/LaB6–ITO nanocomposite (PLINC) films by a solution casting method. X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, thermogravimetric analysis (TGA) and ultraviolet–visible–near infrared spectroscopy (UV–vis–NIR) were employed to characterize the PLINCs. The TGA and UV–vis–NIR results reveal that the nanocomposite films possessed outstanding thermal stability. The temperature where 5 % weight loss of the PVB matrix was improved after the addition of LaB6 and ITO particles and the property for blocking near infrared light was also enhanced as compared with the case of pure PVB film.

Polymer Photovoltaics With Top Metal Electrode Deposited by Solution-Processing

In this paper, fully solution-processed organic solar cells were fabricated on prepurchased tin-doped indium oxide (ITO)-coated glass using the inverted architecture. Solution-processed electrodes consisting of ITO nanoparticle, silver (Ag) nanowire, or Ag nanoparticle films were used as the anode in the devices. Electrode deposition for solution-processed components was accomplished by using a commercially available airbrush with compressed dry nitrogen as the carrier gas. Morphologies of the deposited electrodes and the solution-processed electron blocking layer can be seen as topography images using atomic force microscopy. Cells fabricated with a solution-processed electrode show comparable device performances to that of an evaporated electrode using a similar structure.

Transparent conductive coatings of hot-pressed ITO nanoparticles on a plastic substrate

Abstract Tin-doped indium oxide (ITO) nanoparticle coatings were prepared on plastic substrates via a hot-press method. The ITO coatings showed electrical conductivity after both pressure and heat were applied. Resistivity decreased as both temperature and pressure increased. However, when the temperature and pressure increases were excessive, cracks were generated in the coatings and there was an expansion of the substrate film, which diminished conductivity. Also, when the coating was hot-pressed at a temperature that was too high, transmittance was diminished. To produce transparent conductive coatings, the optimal conditions for pressure and temperature were determined to be 1000 kg/cm 2 and 120 °C, respectively. Annealment in a 5% hydrogen–argon mixed gas further improved the electrical conductivity of the coatings.

Synthesis of Ni/ITO nanocomposite with excellent electromagnetic absorption via in situ reducing reaction

Ni/ITO nanocomposite was prepared via a facile in situ reducing route. ITO nanoparticles not only work as separating mediums to prevent Ni nanoparticles from agglomeration but also provide the nanocomposite with extra interfacial polarization mechanism for electromagnetic wave absorbing. As a result, as-fabricated Ni/ITO nanocomposite exhibits both an unexpected magnetic resonance behavior and an enhanced dielectric loss, which could find promising applications in the field of microwave absorption.