2O5 Electrodes Research Articles

Performance Enhancement of Ti/IrO2-Ta2O5 Anode through Introduction of Tantalum-Titanium Interlayer via Double-Glow Plasma Surface Alloying Technology.

Ti/IrO2-Ta2O5 electrodes are extensively utilized in the electrochemical industries such as copper foil production, cathodic protection, and wastewater treatment. However, their performance degrades rapidly under high current densities and severe oxygen evolution conditions. To address this issue, we have developed a composite anode of Ti/Ta-Ti/IrO2-Ta2O5 with a Ta-Ti alloy interlayer deposited on a Ti substrate by double-glow plasma surface alloying, and the IrO2-Ta2O5 surface coating prepared by the traditional thermal decomposition method. This investigation indicates that the electrode with Ta-Ti alloy interlayer reduces the agglomerates of precipitated IrO2 nanoparticles and refines the grain size of IrO2, thereby increasing the number of active sites and enhancing the electrocatalytic activity. Accelerated lifetime tests demonstrate that the Ti/Ta-Ti/IrO2-Ta2O5 electrode exhibits a much higher stability than the Ti/IrO2-Ta2O5 electrode. The significant improvement in electrochemical stability is attributed to the Ta-Ti interlayer, which offers high corrosion resistance and effective protection for the titanium substrate.

Fabrication of novel Ti/SnO2-Nb2O5 electrode in comparison with traditional doping metal oxides for electrochemical textile wastewater treatment

Textile wastewater contains a number of hazardous and refractory organic contaminants, especially various dyes such as cibacron, cycafix, monozol, and procion, that contribute to the negative effects of textile wastewater on aquatic creatures due to a limitation of light penetration and the consumption of oxygen. The selection of electrode materials is always a primary concern for electrochemical methods. SnO2-based electrodes are now being pursued by researchers due to their low cost. As a result, adding another stable oxide is recommended to enhance the efficiency and stability of SnO2-based electrodes. This study aims to fabricate the Ti/SnO2-Nb2O5 electrodes in comparison with different traditional doping metal oxides, Ti/SnO2-Sb2O5, Ti/SnO2-TiO2, and Ti/SnO2-Ta2O5, using the sol–gel method for electrochemical textile wastewater treatment. The electrode’s surface morphologies, crystal structures, and electrochemical characteristics were determined using scanning electron microscopy (SEM), X-ray diffraction (XRD), and cyclic voltammetry (CV), respectively. The SEM images illustrated that the surfaces of the four electrodes had typical cracking structures of mixed metal oxide electrodes. The presence of crystalline structures of SnO2, Sb2O5, Nb2O5, TiO2, and Ta2O5 on the electrodes was clearly determined. The direct experimental comparisons indicated that the Ti/SnO2-Nb2O5 electrode performed the best among the four oxides in the treatment of textile wastewater, with 87.0% and 84.3% efficiency in removing COD and color, respectively. A current density of 5.8 mA/cm 2 and a NaCl concentration of 2 g/L were found to be optimal operating conditions. The electrochemical properties of the fabricated electrodes showed a high oxygen evolution potential, stability, and the generation of numerous free radicals and oxidants such as •OH, H2O2, O3, and Cl2. These findings serve to inform the future selection of appropriate metal oxides to reinforce SnO2 electrodes for textile wastewater treatment.

Application of Ti-based mixed metal oxide electrodes towards electrochemical mineralization of Metronidazole: Evaluation of influencing factors and removal by-products

BackgroundThe treatment of Metronidazole (MTZ) as a persistent pharmaceutical waste in the water is a significant challenge. To reduce the adverse effect of MTZ in water, we tested a novel SiO2-incorporated MMO-Ti/IrO2-Ta2O5 electrode via the electrochemical oxidation (EO) method. MethodsThe electrode was characterized by scanning electron microscopy, energy dispersive spectrum, atomic force microscopy, and cyclic voltammetry analyses. Structural characterization results were represented high resistance, compact surface, and better electrocatalytic properties for Ti/IrO2-Ta2O5-SiO2 electrode. The influence of critical operational parameters, including applied current density, initial pH, initial concentration of MTZ, and electrolysis time, was detected on electrocatalytic removal efficiency. Significant findingsIt was recognized that the high electrocatalytic power of SiO2-incorporated MMO-Ti/IrO2-Ta2O5 electrode gives a high amount of •OH during the removal process. At optimum conditions (pH = 7, J = 200 mA/cm2, [MTZ]0 = 40 mg/L, t = 80 min), 98.76% MTZ removal efficiency was achieved. Besides, comparison analysis was performed with SiO2-incorporated MMO-Ti/IrO2-Ta2O5 electrode and Ti/IrO2-Ta2O5, so results point out the higher total organic carbon removal of about 78.90% and 54.30% with SiO2-incorporated MMO-Ti/IrO2-Ta2O5 than Ti/IrO2-Ta2O5, respectively. Furthermore, MTZ removal intermediates formed during the electrocatalytic oxidation process were identified by the gas chromatography–mass spectrometry technique.

Fabrication of high performance Ti/SnO2-Nb2O5 electrodes for electrochemical textile wastewater treatment

Textile wastewater contains many organic compounds and colors that affect aquatic life and human health when discharged into the environment. High coloration due to excess dyes entering the wastewater causes coloration to the receiving water stream, affects the photosynthesis process of aquatic species, and adversely affects the landscape. SnO2-based electrodes have been extensively used in electrochemical water treatment, but their low durability decreases the pollutant treatment ability. Therefore, it is necessary to add another stable oxide to improve the performance and stability of SnO2 electrodes. This study aims to fabricate Ti/SnO2-Nb2O5 electrodes for the textile wastewater treatment using the electrochemical oxidation method. Different molar ratios of SnO2:Nb2O5 coating were prepared using the sol-gel method and then coated on the Ti substrates for calcination in 60 min at 500 °C. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer Emmett Teller (BET), and cyclic voltammetry (CV) were used to determine the surface and electrochemical properties of Ti/SnO2-Nb2O5 electrodes. The SEM images show that SnO2-Nb2O5 electrode surfaces have the appearance of typical cracking structures of mixed metal oxides electrodes. The XRD spectrum show the SnO2 peaks of facet (110), (101), (200), (301), (321) and Nb2O5 peaks of facet (001), (002), (100), (101), (102) on Ti substrates. Furthermore, the specific surface area of the Ti/SnO2-Nb2O5 electrode ranges from 37.354 m2/g (SnO2:Nb2O5 = 9:1) to 71.885 m2/g (SnO2:Nb2O5 = 1:9). The electrochemical properties of SnO2:Nb2O5 electrodes showed high oxygen, chlorine evolution potential and high organic pollutant degradation in textile wastewater with COD removal at 83 %, decolorization at 74 % and the generation of many free radicals such as HO•, H2O2, O3, Cl2. The results demonstrate that the Ti/SnO2-Nb2O5 electrode with the mole ratio of 3:7 is the best in textile wastewater treatment with the longest service life (39 h).

Study of the treatment of leachate after biodigestion using Electro-fenton method

Leachate contains many non-biodegradable organic compounds and nutrients with high concentrations, especially from urban waste landfills with long operating times (> 10 years), which affects the human health and environmental quality. Electro-Fenton is one of the advanced oxidation processes (AOPs) that has been recently studied for the treatment of many persistent organic compounds in water. In this study, post-biological leachate (continuous flow biological tank) was treated using Electro-Fenton method with heterogeneous catalysts as Iron (II) Sulfide and Iron Oxide on two electrodes Ti/IrO2-Ta2O5 and Ti/RuO2. The effect of different pH conditions on the pollutant removal efficiency in landfill leachate was studied. The results show that Ti/IrO2-Ta2O5 electrode and Iron (II) Sulfide catalyst obtain better leachate treatment performance than the others under the same experimental conditions. The heterogeneous Electro-Fenton process was capable of removing 71% of chemical oxygen demand (COD), 88% of total organic carbon (TOC), 89% of total nitrogen (TN), 93% of ammonium nitrogen N-NH4 + and 99% color at Ti/IrO2-Ta2O5 electrode and Iron (II) Sulfide catalyst at a pH 3, current density 333 mA/cm2 after 90 minutes of electrolysis. The results showed that the Electro-Fenton method capable effective treatment of pollutants in the post-biological leachate in the future.

Amorphous–crystalline-heterostructured niobium oxide as two-in-one host matrix for high-performance lithium–sulfur batteries

The integration of Li–A/T-Nb2O5 and S–A/T-Nb2O5 electrodes realized an excellent rate capability and cyclability.

Experimental study of a solar-driven photo-electrochemical hybrid system for the decolorization of Acid Red 26

This study presents a new solar-driven hybrid system that integrated a photo-electrochemical reactor with a photovoltaics (PV) panel for azo dyes’ decolorization and electricity generation. Full spectrum of sunlight is utilized to optimize the color removal of Acid Red 26 (AR26) in this hybrid system. Persulfate (PS, S2O42−) was selected as the photochemical oxidant and Ti/IrO2-Ta2O5 electrode was used as the anode. Experiments were made to evaluate the efficiency of decolorization and the performance of PV panels in different reaction conditions outdoors. The results showed that the synergistic effect of two processes was observed for the AR26 decolorization. Comparing with the solar/persulfate process or the electrochemical process alone, the complete color removal time by the hybrid system decreased up to 50% and 44.4% respectively. In this system, the water layer in the flow channel cooled PV panels by absorbing the far infrared spectrum of sunlight, and the increased temperature of wastewater from 7°C to 16°C enhanced the decolorization efficiency of AR26. Moreover, the generated electricity by PV panels could satisfy the energy demand of electrochemical oxidation.

Synthesis and characterization of sulfur/carbon/porous nanostructured V2O5 composite cathodes for lithium sulfur batteries

Porous nanostructured V2O5 (PN-V2O5) was prepared by a facile spray pyrolysis and used as additive to synthesize sulfur/carbon/PN-V2O5 (S/C/PN-V2O5) composite by a combination of wet-ball-milling and heat treatment. The meso- and macropores in PN-V2O5 were confirmed by pore size distribution, which provided the favorable space to accommodate sulfur. The X-ray diffraction analysis showed that the crystal structures of S and V2O5 could be preserved below the heating temperature of 160°C and that high heating temperature (200°C) will result in reaction between S and V2O5. The pore size distribution curves of S/C/PN-V2O5 composites revealed that the penetrated S in PN-V2O5 pores mainly occupied the mesopores and macropores, which was further confirmed by a typical cross-sectional PN-V2O5 with Auger analysis. The S/C/PN-V2O5 composite cathode exhibited a discharge capacity of 632mAhg−1 after 60cycles at the current density of 100mAg−1 and the capacity retention of S/C/PN-V2O5 electrode was 27.3% higher than that of S/C electrode, demonstrating a better cycling performance.

Electrochemical Properties of Porous V2O5/Sulfur/Carbon Composite Electrode Prepared Using a Combination of Aerosol and Powder Technologies

Porous nanostructured vanadium pentoxide (PN-V2O5) prepared by a novel spray pyrolysis was used to synthesize sulfur/carbon/PN-V2O5 (S/C/PN-V2O5) composite through heat treatment and the effect of heat treatment parameters (e.g. heat treatment temperature and heat treatment time) and porous structure of V2O5 on physical and electrochemical properties of S/C/PN-V2O5 composites were investigated. The X-Ray Diffraction results reveal that higher heat treatment temperature of 200 ºC or long heat treatment time (10 h) can promote the chemical reactions between S and V2O5. The Energy Dispersive Spectrometer images of the S/C/PN-V2O5 composite heat treated at 160 ºC for 2 h demonstrated a generally good distribution of three components. The cross-sectional SEM images and elemental mapping analysis revealed the partial penetration of S into PN-V2O5. The electrochemical performance indicated the S/C/PN-V2O5 electrode displayed a discharge capacity of 666 mAh g−1 after 50 cycles which was higher than that of S/C electrode (379 mAh g−1).

Treatment of Amaranth dye in aqueous solution by using one cell or two cells in series with active and non-active anodes

The anodic oxidation of Amaranth dye has been studied by electrochemical measurements (cyclic voltammetry and polarisation curves) and bulk electrolysis employing a single or two cells in a serial mode system using active and non-active anodes (Ti/IrO2-Ta2O5 and Nb/BDD) as electrode materials. The results of electrochemical measurements showed that, Nb/BDD had a significant oxidation power to mineralise Amaranth dye than Ti/IrO2-Ta2O5 anode. Single cells were tested at different current densities (30, 60 and 80mAcm−2). At Nb/BDD anode, total colour elimination and 49.1% of COD removal were achieved by applying 30mAcm−2 after 60min of treatment. Conversely, 98.5% of colour removal and 43.2% of COD decay were accomplished at 60mAcm−2 with Ti/IrO2-Ta2O5 electrode, after 360min of electrolysis time. Supported on the obtained results with single cells, a system in a serial mode was further evaluated for the first time. The arrangement with Ti/IrO2-Ta2O5 electrode at 30mAcm−2 in the first cell followed by Nb/BDD anode at 30mAcm−2 revealed the most interesting results. Complete decolourisation and 75.1% of COD abatement were achieved after 60min with lower energy requirements of about 25.4kWhm−3 (0.2kWhgCOD−1). This study demonstrates the potential of a serial system to be applied as a wastewater pre-treatment approach.

Preparation and Characterization of Nd-Doped Ti/SnO<sub>2</sub>-Sb<sub>2</sub>O<sub>5</sub> Electro-Catalytic Electrodes Used for Reactive Brilliant Red X-3B Wastewater Treatment

The best catalytic capacity of Nd-doped Ti/SnO2-Sb2O5 electrodes was obtained by sol-gel preparation. Nd-doped Ti/SnO2-Sb2O5 coating was characterized using technique such as scanning electron microscopy (SEM), and X-ray diffraction (XRD). Nd-doped electrode fragments looks smaller, more compact and more uniform than undoped electrode through SEM. The crystal cell’s average diameter of Nd-doped electrodes was 3.48nm through XRD. BOD5/COD of Reactive Brilliant Red X-3B increased 200% under optimum conditions after 1h electrolysis. Instantaneous current efficiency (ICE) was 51.15 % in first 40 min, 35.73 % in first 60 min. In the first 40 minutes of electrolysis process, COD of Reactive Brilliant Red X-3B changes conformed to the pseudo first-order kinetic equation. Electrical Properties Tests showed that the oxygen evolution potential values of Nd-doped electrodes were higher than the undoped electrodes in various media.

ChemInform Abstract: Morphological and Microstructural Study of the Ti/IrO2-Ta2O5 Electrode: Effect of the Preparation Temperature.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Microstructure, electrochemical surface and electrocatalytic properties of IrO2+Ta2O5 oxide electrodes

X-ray diffraction (XRD) and scanning electron microscopy (SEM) have been used to characterize physical structure of IrO2+Ta2O5 films over the whole composition range by thermodecomposition of chloride solutions heated at 450°C. Solid solubilization between Ta component and IrO2 rutile in the mixed films was measured, and three typical surface morphologies of the oxide coatings were observed. The surface electrochemical properties of Ti/IrO2-Ta2O5 electrodes were studied by cyclic voltammetry at varying potential scan rate, and a ‘double-layer’ electrochemical structure containing the ‘inner’ and ‘outer’ layers has been distinguished. The voltammetric charge appears to decline with the decrease of grain size of oxide coatings as a result of the effect of surface tension. However, the coatings of 70% IrO2+30% Ta2O5 with the finest grains still exhibit the highest apparent activity for oxygen evolution evaluated by the anodic current at a constant potential. This result is interpreted by the measurements of open-circuit potential (Eoc) and double-layer capacitance (Cdl) using electrochemical impedance spectroscopy (EIS). Thereby, the reliability of voltammetric charge obtained in ‘double-layer’ potential region in determining the real electrocatalytic activity for O2 evolution has been discussed.

Electrochemical properties of Ti/SnO2-Sb2O5 electrodes prepared by the spray pyrolysis technique

Cyclic voltammetry for the ferri-ferrocyanide redox couple has been used to study the Ti/SnO2-Sb2O5 electrode prepared by spray-pyrolysis under different conditions. The obtained results shows that increasing the preparation temperature and the duration of coating deposition results in a decrease of ip and an increase of ΔEp for the ferri-ferrocyanide couple. This deviation from reversibility has been attributed to the formation of a titanium oxide layer at the Ti/coating interface. Concerning oxygen evolution at the Ti/SnO2-Sb2O5 anodes, a mechanism is proposed in which water is discharged at the anode forming hydroxyl radicals which are further oxidized to form dioxygen. Finally, a generalized mechanism for oxygen evolution at oxide electrodes has been proposed.

Long service life IrO2/Ta2O5 electrodes for electroflotation

Ti/IrO2-Ta2O5 electrodes prepared by thermal decomposition of the respective chlorides were successfully employed as oxygen evolving electrodes for electroflotation of waste water contaminated with dispersed peptides and oils. Service lives and rates of dissolution of the Ti/IrO2-Ta2O5 electrodes were measured by means of accelerated life tests, e.g. electrolysis in 0.5M H2SO4 at 25°C and j = 2 A cm−2. The steady-state rate of dissolution of the IrO2 active layer was reached after 600–700 h (0.095 μg Ir h−1 cm−2) which is 200–300 times lower than the initial dissolution rate. The steady-state rate of dissolution of iridium was found to be proportional to the applied current density (in the range 0.5–3 A cm−2 ). The oxygen overpotential increased slightly during electrolysis (59–82 mV for j = 0.1 A cm−2 ) and the increase was higher for the lower content of iridium in an active surface layer. The service life of Ti/IrO2 (65 mol%)-Ta2O5 (35 mol%) in industrial conditions of electrochemical devices was estimated to be greater than five years.