Tin Cathode Research Articles

Electrocatalytic Stability of Tin Cathode for Electroreduction of CO₂ to Formate in Aqueous Solution.

The electrocatalytic stability of tin (Sn) nanoparticle for electrochemical reduction of CO2 to formate was measured using an H-type cell during electrolysis for 40 h. The Faradaic efficiency (FE) and partial current density (PCD) of formate formation reduced as much as 10% and 13% of the maximum values, respectively. To elucidate the decrease in FE and PCD, the changes in the morphology, chemical composition, the crystalline structure were investigated. The spherical Sn nanoparticles were pulverized after electrolysis. Furthermore, the crystal structure of the fresh Sn electrocatalyst was collapsed and changed into amorphous phase after 40 h electrolysis. The decrease in FE and PCD of formate production on the Sn/CFP electrode could be mainly originated from the reduction of the SnOx to Sn on the cathode surface during electrolysis.

A self-heated hollow cathode made of compacted TiN powder: the preparation method and test results

A method for the formation of a tubular hollow self-heated cathode using magnetic-pulse pressing of a mixture of TiN (90%) and Ti (10%) powders with subsequent annealing and sintering during operation of the compact as a cathode in a high-current (5–45 А) discharge at temperatures of 2000–2200°C is described. Massive tubular cathodes with a 2.5-mm-thick wall and a large (up to 12 mm) inner diameter were manufactured. The erosion rate of a TiN cathode was 2.3 × 10–7 g/C for the operation in an Ar/N2 mixture and increased by a factor of 1.6 in the oxygen–argon plasma generation mode with separate feeding of gases.

CO2 Conversion to Formic Acid in a Three Compartment Cell with Sustainion™ Membranes

Formic acid generated from CO2 has been proposed both as a key intermediate renewable chemical feedstock as well as a potential energy storage chemical media for hydrogen. In this paper, we describe a novel three compartment electrochemical cell configuration with the capability of directly producing a pure formic acid product in the concentration range of 5 – 20 wt% at high current densities and Faradaic yields. The electrochemical cell employs a Dioxide Materials Sustainion™ anion membrane, allowing for the improved CO2 electrochemical reduction performance. Stable electrochemical cell performance for more than 500 hours has been experimentally demonstrated. Figure 1 shows the current produced as a function of the cell voltage in a cell with a tin cathode, and IrO2 anode, and deionized water in the middle compartment with no electrolyte added to the water. Notice that one can obtain up to 200 mA/cm² at reasonable cell voltages. Figure 2 shows how the exit concentration and Faradaic efficiency varies with flowrate. Experimentally, as the Faradaic efficiency decreases as the formic acid concentration rises. Physically, the some of the formic acid is transported to the anode, where it is oxidized leading to formic acid loss. The use of thicker and/or higher MW PSA cation membranes significantly reduces these formate losses. Figure 3 shows a steady state run. In this case, we are able to maintain an output concentration of 15% formic acid for 500 hours, with no significant change in cell voltage. Figure 1

Electrochemical Behavior of Dy2O3 on Molybdenum and Liquid Tin Electrodes in Molten CaCl2

The electrochemical behavior of dysprosium oxide at a solid molybdenum and a liquid tin electrodes have been investigated by cyclic voltammetry and square wave voltammetry in molten CaCl2 at 1173 K. It was investigated that deposition potentials of calcium and dysprosium at liquid tin electrode are more positive than those at a solid molybdenum electrode. Meanwhile, our results proved that the dysprosium oxide can be reduced at both molybdenum and liquid tin electrodes. There are two steps for Dy2O3 reducing on Mo electrode while only one reduction step can be seen on liquid tin electrode. The Dy-Sn alloys were obtained through long time electrolyzing on a liquid tin cathode. The reduction mechanism for the reducing process was also investigated in this paper.

Development of an Electrochemical Process for the Simultaneous Treatment of Wastewater and the Conversion of Carbon Dioxide to Higher Value Products

AbstractMany researchers have shown that selected anodic processes allow effective treatment of a very large amount of wastewater contaminated by pollutants resistant to biological processes. In the meantime, various authors have also shown that carbon dioxide can be converted into higher value products, such as formic acid or synthesis gas, by cathodic reduction at suitable cathodes. These two processes present interesting economic potential that, however, still needs to be improved for further development at an industrial level. Herein, these two kinds of process are combined in the same cell to improve their economic feasibility. In particular, the anodic treatment of wastewater at a boron‐doped diamond anode and the cathodic reduction of carbon dioxide to formic acid at a tin cathode are performed simultaneously in a divided cell. Aqueous solutions of Acid Orange 7, which is a widely used azoic dye resistant to conventional biological processes, are used as a model for wastewater. The effect of various operating parameters (including current density, mixing rate, and pH) on both processes is studied. It is possible, under optimized operating conditions, to successfully achieve in a single reactor both the treatment of wastewater contaminated by resistant pollutants and the conversion of carbon dioxide into formic acid. This paired electrolysis process can improve substantially economic figures with respect to each separate process.

Probing the Mechanism of Aqueous CO2 Reduction on Post-Transition-Metal Electrodes using ATR-IR Spectroelectrochemistry

The role of metastable surface oxides in the reduction of CO2 on lead, bismuth, tin, and indium electrodes was probed using in situ attenuated total reflectance infrared (ATR-IR) spectroelectrochemistry. The effect of the surface oxide on the Faradaic efficiency of CO2 reduction to formic acid was studied by etching and anodizing the electrodes, and the results were correlated with respect to the observed spectroscopic behavior of the catalysts. A metastable oxide is observed on lead, tin, and indium cathodes under the electrochemical conditions necessary for CO2 reduction. Spectroscopic evidence suggests that bismuth electrodes are fully reduced to the metal under the same conditions. The dynamics of the electroreduction of CO2 at lead and bismuth electrodes appears to be different from that on on tin and indium electrodes, which suggests that these catalysts act through different mechanistic pathways. The post-transition-metal block can be divided into three classes of materials: oxide-active materials,...

Enhanced stability of complementary resistance switching in the TiN/HfOx/TiN resistive random access memory device via interface engineering

This study shows that a majority (70%) of TiN/HfOx/TiN devices exhibit failed complementary resistance switching (CRS) after forming. In conjunction with the consistent observation of a large non-polar reset loop in the first post-forming voltage-sweep measurement, it is proposed that breakdown of the TiN/HfOx interfacial oxide layers (crucial in enabling CRS) and the accompanied formation of Ti filaments (due to Ti migration from the TiN cathode into the breakdown path) resulted in CRS failure and the observed non-polar reset behavior. This hypothesis is supported by the significant reduction or complete elimination of the large non-polar reset and CRS failure in devices with a thin Al2O3 layer incorporated at the TiN-cathode/HfOx or both TiN/HfOx interfaces. The higher breakdown field of the thin Al2O3 enables it to sustain the forming voltage until the forming process is interrupted, thus enabling CRS via oxygen exchange with the adjacent vacancy-type filament formed in the HfOx.

Electrochemical reduction of carbon dioxide to formic acid at a tin cathode in divided and undivided cells: effect of carbon dioxide pressure and other operating parameters

The reduction of carbon dioxide to formic acid at a tin cathode was studied in both divided and undivided cells. In the first stage of the study, the effect of some operating parameters, including the working potential and the nature of the supporting electrolyte and of the cathode, on both the cathodic reduction of CO2 and the anodic oxidation of formic acid was investigated in a divided cell. In a second stage, the reduction of carbon dioxide was performed in an undivided cell with the aim of studying the effect on the generation of formic acid of various operating parameters such as current density, cathode to anode area ratio, mixing rate and nature of the anode and of the supporting electrolyte. A detailed investigation on the effect of the carbon dioxide pressure was also carried out. The utilization of relatively high CO2 pressures (15–30bar) allowed to achieve high concentrations of formic acid (up to 0.46molL−1) working with high current density (up to 90mAcm−2) and using cheap and simple undivided cell and electrodes.

Observation of Self-Reset During Forming of the TiN/HfOx/TiN Resistive Switching Device

Study on complementary resistive switching of TiN/HfOx/TiN memory device has shown that the device is highly susceptible to self-reset, i.e., the device is automatically programmed into the high-resistance state during forming. This is observed in the following opposite-polarity voltage sweep, in which the device exhibits a set behavior (instead of a reset as typically observed in bipolar switching mode). Interestingly, the self-reset behavior is: 1) suppressed in devices with a thin Al2O3 layer inserted in-between the TiN and HfOx and 2) completely eliminated in devices with the TiN cathode replaced by Pt. These results are consistent with a hypothesis that ascribes the self-reset to the migration of oxygen ions from the cathode interfacial oxide into the conducting filament in the HfOx during the forming transient, thus resulting in the disruption of the filament. With the reduction in voltage loading across the cathode interfacial oxide during forming transient in devices with the Al2O3 interlayer and the elimination of interfacial oxide in devices with the Pt cathode, the occurrence of self-reset is reduced or eradicated.

Microfluidic White Organic Light-Emitting Diode Based on Integrated Patterns of Greenish-Blue and Yellow Solvent-Free Liquid Emitters.

We demonstrated a novel microfluidic white organic light-emitting diode (microfluidic WOLED) based on integrated sub-100-μm-wide microchannels. Single-μm-thick SU-8-based microchannels, which were sandwiched between indium tin oxide (ITO) anode and cathode pairs, were fabricated by photolithography and heterogeneous bonding technologies. 1-Pyrenebutyric acid 2-ethylhexyl ester (PLQ) was used as a solvent-free greenish-blue liquid emitter, while 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyltetracene (TBRb)-doped PLQ was applied as a yellow liquid emitter. In order to form the liquid white light-emitting layer, the greenish-blue and yellow liquid emitters were alternately injected into the integrated microchannels. The fabricated electro-microfluidic device successfully exhibited white electroluminescence (EL) emission via simultaneous greenish-blue and yellow emissions under an applied voltage of 100 V. A white emission with Commission Internationale de l’Declairage (CIE) color coordinates of (0.40, 0.42) was also obtained; the emission corresponds to warm-white light. The proposed device has potential applications in subpixels of liquid-based microdisplays and for lighting.

Mechanistic Insights into the Reduction of CO2 on Tin Electrodes using in Situ ATR-IR Spectroscopy

The reduction of CO2 on tin cathodes was studied using in situ attenuated total reflectance infrared spectroscopy (ATR-IR). Thin films of a mixed Sn/SnOx species were deposited onto a single-crystal ZnSe ATR crystal. Peaks centered at about 1500, 1385, and 1100 cm–1, attributed to a surface-bound monodentate tin carbonate species, were consistently present under conditions at which CO2 reduction takes place. It was shown that these peaks are only present at potentials where CO2 reduction is observed. Moreover, these peaks disappear if the pH of the reaction is too low or if the tin surface is chemically etched to remove surface oxide. Sn6O4(OH)4 and SnO2 nanoparticles were shown to be catalytically active for CO2 reduction, and insights into the oxidation state of the catalytically active species are gained from a comparison of the catalytic behavior of the two nanoparticle species. From these experiments, a mechanism governing the reduction of CO2 on tin electrodes is proposed.

Electrochemically depositing titanium(iii) ions at liquid tin in a NaCl–KCl melt

The electrochemical behavior of titanium ions at a liquid tin cathode has been investigated in a NaCl–KCl melt at 1023 K.

Microfabricated, continuous-flow, microbial three-electrode cell for potential toxicity detection

Bioelectrochemical microfluidic devices are developed based on the continuous flow mode of membrane-less, microbial three-electrode cells (M3Cs). These novel devices are the miniaturized microfluidic-based three-electrode cells for the first time, and these are composed of an Ag/AgCl reference electrode, indium tin oxide anode and cathode electrodes. The basic performance of the devices is tested using biofilms grown from wastewater inoculum in an experiment that senses for toxic materials. The toxic materials used are: sodium cyanide, imidazole, and sodium azide in concentrations of 0.02–0.8 mM, with lactate and sodium acetate functioning as substrates. While a constant potential of 0.2 V is applied to the working electrodes of the device, the bioelectrocatalytic oxidation current is monitored at 35°C. When the biocides are introduced, the response current from the cell decreases. The sensor can detect imidazole at the range of 0.02–0.4 mM. The experimental results show the potential of using microfluidic-based microbial electrolysis cells not only as biocide sensors, but also as investigative tools for microbial electrochemical assays.

Integration of Anodic and Cathodic Catalysts of Earth-Abundant Materials for Efficient, Scalable CO2 Reduction

A fully integrated electrochemical cell for co-production of formate (HCOO−) and oxygen (O2) from carbon dioxide (CO2) and water using only earth-abundant elements has been developed. The process converts CO2 to formate using electrons derived from anodic water oxidation. A novel cathodic catalyst system, consisting of a tin (Sn) cathode in combination with the soluble heterocycle 2-picoline, was identified for CO2 reduction. Water oxidation takes place at a fluorine-doped tin oxide electrode coated with an electrodeposited cobalt oxide (CoOx) electrocatalyst. Use of 2-picoline as a soluble cathodic co-catalyst lowered the overpotential and enhanced the stability of the Sn-mediated CO2 reduction process. Fluorophosphate served as a redox-stable electrolyte to buffer the anode compartment at mildly acidic pH (~ 5 to 5.5), thereby stabilizing the CoOx electrocatalyst and supporting efficient water oxidation. The complete electrochemical cell maintained a stable cell voltage of less than 3 V over 5 days, with an average formate faradaic yield of 34 %. These results are presented together with an economical analysis of large-scale solar-driven production of formate/formic acid from CO2 and water.

Optical observations of post-discharge phenomena of laser-triggered discharge produced plasma for EUV lithography

This paper reports the dynamic post-discharge phenomena of laser-triggered discharge-produced plasmas (LTDPP) for extreme ultraviolet lithography (EUVL) sources. A pulsed laser was focused on the high-voltage tin cathode surface to form tin vapor jet across a 5 mm long anode–cathode gap, which leads to the electrical breakdown. The post-discharge phenomena were observed using both of the Schlieren method and high-speed camera. Schlieren images show the dynamic evolution of the discharge plasma and the development of tin droplets. Visible emission from the plasma lasted for more than 1 µs after the current stopped. The droplets emerged from the cathode approximately 100 µs after discharge and spread throughout the electrodes gap. Various sizes of droplets stagnate in the gap for milliseconds. The subsequent laser pulse and voltage application show an interaction between the droplets and the subsequent discharge. The subsequent laser pulse evaporates not only the cathode surface but also the droplets, which influence the tin vapor distribution in the gap. This uncertain vapor distribution affects the formation process of microplasmas that emit EUV.

Electrochemical reduction of aqueous nitrate ion at tin cathodes

The remediation of nitrate-contaminated water using electrochemical reduction at a tin cathode has previously been shown to give almost quantitative denitrification (removal of dissolved nitrogen species) under highly cathodic polarization. A particular focus of this project was to identify specific role(s) for tin in the reaction in the context of the previous literature. The current efficiency for denitrification was enhanced in alkaline solution, and the reaction was accelerated by the presence of small concentrations of Sn(II) salts, which are in a dynamic exchange between cathodic deposition and corrosion of the cathode. Literature precedent indicates that Sn(II) salts promote the “dimerization” pathway of NO to hyponitrite in preference to reduction to ammonia. Hyponitrite is a known intermediate in the electrochemical reduction of nitrate, but its spontaneous decomposition gives predominantly N2O, which does not reduce further to N2. We have shown that hyponitrite is reduced electrochemically in competition with its thermal decomposition, which provides a pathway to N2 via the spontaneous dehydration of HO−NH−NH−OH. The possible role of surface-bound Sn−H species in the reduction mechanism is discussed, but further work is needed to substantiate this proposal.

Continuous electrochemical reduction of carbon dioxide into formate using a tin cathode: Comparison with lead cathode

Electrochemical reduction has been pointed out as a promising method for CO2 valorisation into useful chemicals. This paper studies the influence of key variables on the performance of an experimental system for continuous electro-reduction of CO2 to formate, when a tin plate is used as working electrode. Particular emphasis is placed on comparing the performance of Sn and Pb as cathodes. As was previously found with Pb, the influence of current density (“j”) using Sn was particularly noteworthy, and when j was raised up to a limit value of 8.5mAcm−2, important increases of the rate of formate production were observed at the expense of lowering the Faradaic efficiency. However, unlike what was found with Pb, the performance using Sn improved when the electrolyte flow rate/electrode area ratio was increased within the range studied (0.57–2.3mLmin−1cm−2). In this way, the use of Sn as cathode allowed achieving rates of formate production that were 25% higher than the maximum rates obtained with Pb, together with Faradaic efficiencies close to 70%, which were 15 points higher than those with Pb. These results reinforce the interest in Sn as electrode material in the electro-reduction of CO2 to formate.

Electrochemical removal of bromate from drinking water

ABSTRACT The electrochemical removal of bromate on a tin cathode has been studied by both electrochemical techniques, such as cyclic voltammetry and chronoamperometry, as well as by steady-state electrolytic experiments. The reduction of bromate in 2 M NaCl takes place efficiently at potentials more negative than −1.4 V vs. Ag/AgCl and the rate of the reduction displays a maximum at about −1.8 V, then decreases and consequently it increases again as the potential becomes more negative than −1.9 V. The % removal efficiency of bromate displays a maximum (75.6%) at −1.8 V, while the % selectivity of bromide displays a minimum (70.3%) at the same potential.

Influence of the electrode and the pH on the rate and the product distribution of the electrochemical removal of nitrate

The effect of the nature of six metal electrodes (Sn, Bi, Pb, Al, Zn, In) on the rate and the distribution of the products of the electrochemical reduction of nitrate was studied. The product distribution depends on the nature of the metal only quantitatively, while the rate of the reduction was found to be about the same on all metals when the electrolysis was performed at the same rational potential (Er), which is the difference between the applied potential and the potential of zero charge of each metal. Based on these results it was concluded that the mechanism of nitrate reduction is the same for all cathodes studied. Additionally, the influence of the initial pH on the rate of the reduction of nitrate and the selectivity of the products on a tin cathode was studied. The rate of the reduction increases linearly with the concentration of hydronium ion in the pH range 0–4, whereas it is not dependent on the pH at higher pH values. The main products at pH>4 were nitrogen, nitrous oxide, ammonia and nitrite, while at pH 0–4 ammonia and hydroxylamine were mainly formed.

Fabrication and performance evaluation of microfluidic organic light emitting diode

In this study, we fabricated a microfluidic organic light emitting diode (OLED) and evaluated its performance. The microchip consisted of a 3×3 matrix array of OLED pixels in SU-8 microchannels sandwiched by indium tin oxide (ITO) anode and cathode pairs. Liquid organic semiconductors introduced into the microchannels were employed as the light emitters. Electroluminescence was successfully observed at the emitting area of the microchannels. A current density of 0.298mA/cm2 was measured at 70V. In our prototype microfluidic OLED, the patterning of the liquid emitters was confirmed in the microchannels on a single chip. This result shows that the proposed structure can be applicable for liquid-based display.