Antimony-doped Tin Dioxide Research Articles

Electrochemical Degradation Pathway of Phenol on Ti/SnO<sub>2</sub> Anode

The electrochemical degradation pathway of phenol, as model organic pollutant, was investigated on antimony doped tin dioxide electrode based on titanium anode (Ti/SnO2). Many intermediates of electrochemical degradation of phenol on Ti/SnO2 were identified and quantified by HPLC. These intermediates were assured as aromatic ring-compounds (hydroquinone, catechol, benzoquinone, et al) and short chain fatty acids (maleic acid, fumaric acid, formic acid, cis muconic acid and 2-oxoglutaric acid, et al). Electrochemical degradation tests were conducted with some intermediates as substrates, including the electrochemical oxidation of formic acid, acetic acid, oxalic acid, malonic acid, acrylic acid, succinic acid, fumaric acid, maleic acid, and 2-oxaglutaric acid, et al. The degradation pathway of phenol on Ti/SnO2 anode was concluded. It is proven that the pathway relates to the element composition on the electrode surface. These findings demonstrate electrochemical degradation of organic pollutants mechanism and help to practical use of catalytic anodes materials.

Nanoparticles of antimony doped tin dioxide as a liquid petroleum gas sensor: effect of sizeon sensitivity

The gas sensitivity exhibited by nanoparticles of 1 wt% Pd catalysed antimony doped tin dioxide(ATO) prepared by a citrate–nitrate process is reported here. The reduction of particle size to < 3 nm, a dimension smaller than double the thickness of the charge depletion layer,has resulted in an exceptionally high butane sensitivity and selectivity. Thesensitivity and selectivity of ATO particles of different sizes unequivocally provedthat reducing the size of particles to below twice the Debye length dimensionproduces materials with exceptionally high sensitivity and selectivity for sensorapplications. The sensitivity of the samples towards 1000 ppm butane varied in the order98% > 55% > 47%, forCNP > SP > CP samples having crystallite sizes of the order of 2.4 nm to 18 nm to 25 nm,respectively. The ATO nanoparticles exhibited not only a remarkableincrease in gas sensitivity of around 98% towards 1000 ppm butane at350 °C, but also a preferential selectivity to butane compared to other gases such as CO,CO2,SO2,CH4 andH2. In addition to the exceptionally high sensitivity and selectivity, the developed sensors alsoexhibited an improved response time and long term stability, which are of paramountimportance for practical device development.

Electrochemical treatments using tin oxide anode to prevent biofouling

Organic matter and living micro-organisms are responsible for surface modifications of any materials immersed in seawater. This phenomenon, called biofouling, has many detrimental effects and has to be prevented. Electrochemistry could be a very efficient tool for biofouling prevention in two ways, either by local biocide production through seawater electrolysis or by immobilizing electrogenerated biocides. In this paper, both strategies will be developed and illustrated in the particular case of tin dioxide as anode material. Chloride and bromide ions present in seawater are efficiently oxidized at antimony doped tin dioxide to form biocidal hypohalogenous acids, namely HOCl and HOBr. Underwater optical instruments having glass window coated with a transparent tin dioxide layer can be effectively protected against biofouling without environmental damages because hypohalogenous acids are produced at a low level and on the window itself. Another possibility explored in this paper is to perform a pre-treatment of the surface to be protected. It consists in seawater electrolysis in the presence of organic macromolecules, as for instance bovine serum albumin. In these conditions, chlorinated and brominated organic deposit is formed on the tin oxide surface as proved by EDX and XPS analyses. By testing adhesion and growth of Escherichia coli bacteria, it was shown that this deposit possesses biocidal property. Actually, this property is due to the presence of chloramine and bromamine groups.

Selective Sorption of Technetium on Antimony-Doped Tin Dioxide

Glassy, nanocrystaline antimony-doped hydrous tin dioxide was alkali precipitated from acidic metal chloride solution. The material has good thermal stability and granular physical form that enables its use in a conventional column. The material shows excellent, almost quantitative, uptake properties for 99Tc radionuclide. Its distribution coefficients (Kd values) for 99Tc were typically over 1 000 000 (ml/g) in solutions of one molar ionic competition (at neutral pH) and the uptake remained high over a broad pH range (2-11). By comparison, conventional cation/anion resins yielded Kd values of less than 200. The Tc uptake mechanism of antimony-doped tin dioxide is most likely a sorption process that cannot be categorized as typical cation or anion exchange. Redox reactions between Tc and Sb were speculated as being the phenomenon. Thermal treatment increased the materials crystal size from amorphous to ∼15 nm and changes in the oxidation state of antimony from +3 to +5 occurred at temperatures above 400°C. Also, the material's Tc uptake properties were increased by the thermal treatment.

Phenol degradation on novel nickel-antimony doped tin dioxide electrode

Nickel and antimony doped tin dioxide is a novel anodic material for its good performance of electrochemical ozone generation and direct electro-catalytic oxidation. Electro-catalytic oxidation of phenol on this novel nickel-antimony doped tin dioxide electrode is presented here. The morphology and composition of the electrode are characterized. The effects of applied current densities on phenol degradation rate, energy consumption and coulomb efficiency are discussed. In 0.1 M sulfuric acid, after 4 h electrolysis with current density of 25 mA cm(-1), 90% phenol is removed. And with current density of 20 mA cm(-1), the highest energy efficiency of 6.85 g kWh(-1) and the highest coulomb efficiency of 6.87 μg C(-1) are obtained. The effect of current densities on TOC removal is also discussed.

The effect of dopant’s valence (+III and +V) on the anion/cation uptake properties of antimony-doped tin dioxide

Abstract Antimony is perhaps the most frequently used doping element of tin dioxide. Although antimony of different oxidation states have been used in the synthesis, the effect of dopant’s valence on ion exchange properties has not been investigated critically. In our study the valence of antimony had clear effects on the metal uptake properties of Sb-doped SnO2 materials. Extremely high Tc uptake (Kd &gt; 100 000 mL g−1) on Sb(III)-doped material was observed in conditions under which Sb(V)-doped material did not show any Tc uptake. However, the Sb(V)-doped material showed good Ni2+ uptake properties (Kd up to 33 000 mL g−1), even at pH values below the material’s point of zero charge (pzc), while the Sb(III)-doped material showed Ni2+ uptake only at pH above its pzc. The cation uptake of Sb-doped SnO2 resembles typical weakly acidic cation exchanger character but the uptake of TcO4- does not follow a typical anion exchange pattern. Instead, we propose a sorption process related to redox reactions as the probable Tc uptake process.

Electrochemical oxidation of synthetic tannery wastewater in chloride-free aqueous media

The electrochemical treatment of a synthetic tannery wastewater, prepared with several compounds used by finishing tanneries, was studied in chloride-free media. Boron-doped diamond (Si/BDD), antimony-doped tin dioxide (Ti/SnO 2–Sb), and iridium–antimony-doped tin dioxide (Ti/SnO 2–Sb–Ir) were evaluated as anode. The influence of pH and current density on the treatment was assessed by means of the parameters used to measure the level of organic contaminants in the wastewater; i.e., total phenols, chemical oxygen demand (COD), total organic carbon (TOC), and absorbance. Results showed that faster decrease in these parameters occurred when the Si/BDD anode was used. Good results were obtained with the Ti/SnO 2–Sb anode, but its complete deactivation was reached after 4 h of electrolysis at 25 mA cm −2, indicating that the service life of this electrode is short. The Ti/SnO 2–Sb–Ir anode is chemically and electrochemically more stable than the Ti/SnO 2–Sb anode, but it is not suitable for the electrochemical treatment under the studied conditions. No significant changes were observed for electrolyses performed at different pH conditions with Si/BDD, and this electrode led to almost complete mineralization after 4 h of electrolysis at 100 mA cm −2. The increase in current density resulted in faster wastewater oxidation, with lower current efficiency and higher energy consumption. Si/BBD proved to be the best electrodic material for the direct electrooxidation of tannery wastewaters.

Sensing characterization to NH 3 of nanocrystalline Sb-doped SnO 2 synthesized by a nonaqueous sol–gel route

Antimony-doped tin dioxide (ATO) nanoparticles with high crystallinity during solvothermal synthesis in alcohol were generated from the inorganic precursors (SnCl 4 and Sb(OC 2H 5) 3) and the cationic surfactant (cetyltrimethylammonium bromide, CTAB). The structural and morphological characterizations of the products were performed by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), N 2-sorption isotherm and X-ray photoelectron spectrum (XPS). The resulting particles were highly crystalline oxide particles in the nanometer range (10–14 nm). The indirect-heating sensors using ATO nanoparticles as sensitive materials were fabricated on an alumina tube with Au electrodes and platinum wires. The sensing properties of these sensors based on ATO nanoparticles were investigated. Compared to the original undoped sensor, the results show that the ATO nanoparticles have about 2.5 times increase in response and good dynamic response to NH 3 at low operating temperature (79 °C).

One-step synthesis of antimony-doped tin dioxide nanocrystallites and their property

Antimony-doped tin dioxide(ATO) nanoparticles with primary diameter in the range of 9–10 nm were rapidly synthesized via a novel combustion technique, starting with antimony trichloride and tin tetrachloride as metal sources and self-assembly compounds as fuels. The combustion phenomena and characteristics of products were controlled by assembling components in fuel compounds according to appropriate molar ratio. The as-synthesized products were characterized by XRD, SEM, TEM and XPS, respectively. The electrical conductivity was evaluated through measuring the antistatic property of polyester fiber treated by the as-synthesized products. The results show that a mild combustion phenomena without release of smoke can be taken on and perfect azury rutile ATO crystal with complete substitution can be formed rapidly under the appropriate synthetic conditions. The antistatic property of the polyester fiber treated by the as-synthesized ATO products is enhanced remarkably. The triboelectricity voltage below 1.0 kV, half life below 1.0 s and surface resistance below 1.0×10 6 Ω can be attained.

Synthesis and properties of pure and antimony-doped tin dioxide thin films fabricated by sol–gel technique on silicon wafer

High-quality antimony-doped tin dioxide (SnO 2:Sb) thin films with various concentrations of Sb have been prepared on Si (1 1 1) wafer by sol–gel technique. The microstructure, surface morphology, composition and optical properties of the films are characterized using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and spectroscopic ellipsometry. It is found that the films are the dominant orientation of (1 0 1) with rutile structure of SnO 2, Sb dopant causes the peak positions in XRD patterns to shift slightly instead of introducing new phases, and the average grain size of the films is about 26 nm. Optical constant, refraction index n from 1.55 to 1.95 in the visible spectral region, was determined through multilayer analyses on their respective pseudo-dielectric functions. It is also found that the optical constants depend strongly on the layers of films, annealing temperature and the concentration of Sb dopant.

Selected-Area Growth of SnO2 Nanowires on TiO2 Layer through Reduction of Hydrogen Gas

SnO2 nanowires were grown on a TiO2/ATO (antimony doped tin dioxide) glass substrate by thermal evaporation at ∼750 °C without any source material (tin oxide powder or metal tin). A SnO2 layer was melted and evaporated from ATO glass substrate. Hydrogen served as a reductant, causing vapor species of SnO and O2 to be formed from the SnO2 layer. The patterned TiO2 layer provided sites with a high surface energy such that the selected-area growth of SnO2 nanowires was achieved. A growth model, based on a vapor–liquid–solid mechanism, for interpreting the growth of the nanowires in our work is proposed. Field emission scanning electron microscopy (FESEM), high-resolution transmission emission microscopy (HRTEM), and cathodoluminescence (CL) were used to characterize the nanowires.

Preparation and characterisation of nanosized antimony-doped tin dioxide powders with a novel post-treatment process

Bismuth-doped tin dioxide (BTO) nanopowders were prepared by wet chemical co-precipitation method using tin tetrachloride (SnCl4) and bismuth nitrate (Bi(NO3)3) as raw materials. Effects of calcination temperature and post treatment methods on particle size and crystalline phase transition of bismuth tin precursor (BTP) were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric-differential scanning calorimetric instrument (TG-DSC) and X-ray photoelectron spectroscopy (XPS). The optimal calcination temperature of BTP was found to be about 873 K. A novel post treatment process with polyacrylamide (PAM) in the preparation of nanometerials was presented for the first time. Experimental results showed that nonionic PAM is a highly effective additive, which not only speeds up the filtration of precursor, but also effectively reduces the formation of hard agglomerates. The average size of BTO nanopowders prepared using nonionic PAM as a filtration aid and disperser is smaller than 10 nm. We believe this post treatment method will come into wide use for preparation of many nanosized materials.

Preparation and characterization of low platinum loaded Pt:SnO 2 electrocatalytic films for screen printed dye solar cell counter electrode

A series of low platinum loaded Pt:SnO 2 electrocatalysts for dye-sensitized solar cells were prepared by the hydrogen reduction method at 120 °C. As prepared and annealed at 630 °C samples containing 1.2%, 2% and 3% platinum loaded antimony doped tin dioxide catalytic powders were characterized. The structure and particle sizes are studied by means of high resolution transmission electron microscopy and X-ray diffraction measurement. The metallic state of platinum nanoparticles was observed by X-ray photoelectron spectroscopy. For the paste preparation, differently loaded Pt:SnO 2 powders were each mixed with the ethylcellulose/terpineol printing media. In order to produce symmetrical Pt/Electrolyte/Pt cells for the electrochemical study the pastes were applied onto transparent conductive oxide coated glass by screen printing technology. The charge transfer resistance of these electrodes to the iodide/triiodide redox system in different electrolytes after the thermal sealing of the cells at 630 °C was investigated by electrochemical impedance spectroscopy, which showed that catalytic performance can be improved by homogenous deposition of catalyst on substrate. The surface morphology of the printed catalytic stripes was imaged by field emission scanning electron microscopy and atomic force microscopy.

High-temperature MEMS Heater Platforms: Long-term Performance of Metal and Semiconductor Heater Materials

Micromachined thermal heater platforms offer low electrical power consumptionand high modulation speed, i.e. properties which are advantageous for realizing non-dispersive infrared (NDIR) gas- and liquid monitoring systems. In this paper, we report oninvestigations on silicon-on-insulator (SOI) based infrared (IR) emitter devices heated byemploying different kinds of metallic and semiconductor heater materials. Our resultsclearly reveal the superior high-temperature performance of semiconductor over metallicheater materials. Long-term stable emitter operation in the vicinity of 1300 K could beattained using heavily antimony-doped tin dioxide (SnO2:Sb) heater elements.

Evaluation of the Electrocatalytic Activity of Antimony-Doped Tin Dioxide Anodes toward the Oxidation of Phenol in Aqueous Solutions

Antimony-doped tin dioxide electrodes supported on titanium have been used in the electrochemical treatment of aqueous solution containing phenol. anode has high efficiency in the elimination of phenol, but its use is hindered by its short service life. The introduction of platinum in the oxide layer (3 or 13 atom %) increases the electrode service life up to two orders of magnitude. The electrocatalytic activity of the electrodes toward phenol oxidation has been analyzed with respect to the amount of platinum in the electrode composition. Voltammetric studies show that the oxidation potential of phenol decreases with the amount of platinum in the oxide layer. The activity for phenol oxidation per electroactive site is higher with the Sb-doped electrode within the zone of electrochemical stability of the solvent. Galvanostatic electrolysis of phenol solutions was performed analyzing several factors that affect the efficiency of the elimination process, such as anode composition, cell design, current density, and phenol concentration. The electrode containing platinum (3 atom %) presents the highest efficiency for phenol removal, even higher than Sb-doped .

Preparation and Characterization of Antimony-Doped Tin Dioxide Electrodes. 3. XPS and SIMS Characterization

Several antimony- and antimony−platinum-doped tin dioxide electrodes supported on titanium have been characterized by X-ray photoelectron spectroscopy (XPS) for surface analysis and secondary-ion mass spectrometry (SIMS) for in-depth profile analysis. The surface analysis of the freshly prepared electrodes indicates that the Sb/Sn ratio in the electrode surface is similar to the nominal composition in the precursor solution, but the amount of Pt is higher than this nominal composition. The presence of platinum also produces the segregation of Sb near the electrode surface. The anodic polarization treatment of the electrode produces changes in its chemical state. The growth of a passivating hydroxide in the outer layer is the main cause of the deactivation of Ti/SnO2−Sb electrodes. The introduction of platinum in the layer prevents the hydroxide formation and modifies the deactivation mechanism of the electrode. The growth of an isolating TiO2 between the support and the active oxide produces the deactivat...

Preparation and Characterization of Antimony-Doped Tin Dioxide Electrodes. Part 1. Electrochemical Characterization

Antimony and antimony-platinum doped tin dioxide electrodes supported on titanium have been prepared by thermal decomposition. Ti/SnO2-Sb electrodes have a cracked-mud structure, typical of oxide electrodes prepared by thermal decomposition. The introduction of platinum in the oxide layer has a packing effect in the coating morphology. The electrochemical characterization of these electrodes has been performed in acid medium, and a relation between the roughness factor (measured from electrode capacitance) and electrochemical porosity (related to the voltammetric charge) has been established. The mechanism for the oxygen evolution reaction has been determined by Tafel measurements indicating that the electrodes prepared are nonactive electrodes. The electrocatalytic activity strongly depends on geometric factors, since the activity toward oxygen evolution increases with the electrochemical porosity. Anodic stability of Ti/SnO 2 electrodes has been checked with accelerated service life tests. The introduction of platinum in the oxide coating increases the service life by 2 orders of magnitude.

Preparation and Characterization of Antimony-Doped Tin Dioxide Electrodes. Part 2. XRD and EXAFS Characterization

Several antimony and platinum doped tin dioxide electrodes supported on titanium have been characterized by X-ray diffraction (XRD) and X-ray absorption spectroscopy (EXAFS) techniques. Ti/SnO2−Sb electrodes show a rutile-type nanostructure with a distorted unit-cell because of the substitution of the Sn(IV) ion by Sb(V). The presence of platinum on the electrode coating modifies the lattice parameters of the SnO2 cell due to an amorphization of tin oxide layers. The structural modifications on the different electrode after anodic polarization−deactivation have been analyzed.

Electrolytic Generation of Ozone on an Antimony-Doped Tin Dioxide Coated Electrode

Dissolved ozone up to 34 mg/L was generated by direct electrolysis of water using a titanium electrode coated with an antimony-doped tin dioxide film. The electrode was prepared by spray pyrolysis at 520°C. The current efficiency of ozone generation was 15% in a 0.1 M HClO 4 aqueous solution at room temperature. The electrolytic generation of ozone depends critically on the composition and morphology of the coating and a good generation was observed with Sb:Sn atomic ratio of 1:7 and a smooth and compact surface with connected particles of 3-5 nm diameter.

Preparation and conductive mechanism of mica titania conductive pigment

Flake mica titania conductive pigment, which characteristically consists of both electrical conductivity and pearlescent effect when covered a layer of ATO (Antimony Doped Tin Dioxide) on its surface, has been prepared by using homogenous precipitation method with mica titania as substrate and urea as precipitant. The hydrolysis of urea and the conductive mechanism of the pigment were discussed and the different substrates of mica and mica titania were compared. Furthermore, this paper studied several critical technological parameters pertaining to the influences on electrical conductivity and pearlescent effect of the pigment such as molar ratio of Sn 4+/Sb 3+, coating quantity and the addition order, etc.