A platinum-like behavior electrocatalyst and solid polymer electrolyte technique used on high concentration of electrochemical ozone water generation (original) (raw)
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Characterization of an electrochemical reactor for the ozone production in electrolyte-free water
Journal of Applied Electrochemistry, 2010
The filter-press electrochemical ozonizer is characterized as a function of the applied electric current, temperature, and linear velocity of the electrolyte-free water. Lead dioxide electroformed on surface of a non-platinized fine mesh stainless steel support was used as anode. Electrolysis of the electrolyte-free water was carried out using the membrane electrode assembly (MEA) adequately compressed by means of a specially designed clamping system. Electrochemical characterization studies were carried out galvanostatically as a function of temperature and linear velocity of the circulating water. It was verified that the electrochemical ozone production (EOP) taking place at the reacting zones formed at the solid polymer electrolyte (SPE)/mesh electrode interface is not considerably affected by circulating water when the linear velocity inside the distribution channels is higher than 1.20 cm s−1. A current efficiency for the EOP of 13% and a specific electric energy consumption of 70 Wh g−1 were obtained when an electric current of 130 A was applied at 30 °C. The reactor service life test revealed that the MEA using the lead dioxide fine mesh electrode as anode and a fine mesh stainless steel electrode as cathode, pressed against the SPE, is stable for the ozone production.
Effects of NaCl and Na2SO4 cathode electrolytes on electrochemical ozone production
Electrochimica Acta, 2012
Effects of NaCl and Na 2 SO 4 catholytes on efficiency and lifetime of an ozone production system consisting of a polymer electrolyte membrane and Pt electrodes were investigated. When 0.5 M NaCl catholyte was used, a current efficiency of 29% and a power efficiency of 76 kWh/kg-O 3 were achieved at an electrolysis current density of 0.5 A/cm 2 . Accelerated degradation experiments revealed that the use of the NaCl catholyte kept the Pt anode surface clean and enabled long operation. The use of 0.5 M Na 2 SO 4 catholyte caused formation of an amorphous PtO 2 film on the Pt anode surface, and the efficiency and lifetime of the system were rapidly decreased. NaCl concentration dependence measurements indicate that NaCl concentration of higher than 0.085 M is required for stable operation of the system. The formation of amorphous PtO 2 films probably degrades the catalytic activity of the Pt anode in O 3 formation reactions. From the dissolution rate of the Pt anode, lifetime of the system is estimated to be 5800 Ah.
Journal of Energy Chemistry, 2015
This work examines the ozone electrogeneration (OE) at a binary coating of different nominal compositions (Pt) x-(TaO y) (100−x) , where x (percentage in the precursor solution) varied between 1% and 100%, coated on titanium substrate prepared by a sol-gel technique. The OE is performed in an artificial tap water at room temperature (25 • C). The percentages of Pt and TaO y in the coating significantly affect the electrocatalytic activity towards oxygen evolution. The oxygen evolution was retarded to a different extent based on the electrode composition. The largest retardation was obtained at the (Pt) 10-(TaO y) 90 electrode (ca. 480 mV positive shift) as compared with the (Pt) 100-(TaO y) 0 electrode. This was reflected in a high current efficiency (CE) of OE (ca. 19.3%) at the former electrode. This value is considered to be among the highest values reported for OE at 25 • C in neutral media. The composite electrodes were characterized by voltammetric and surface techniques. A plausible explanation for the change of the efficiency of OE with the electrode composition is given based on the electrochemical results.
Electrochimica Acta, 2003
The nature of the electrolyte strongly influences the electrode kinetics of the oxygen evolution reaction (OER) and electrochemical ozone production (EOP) mainly by affecting the degree of coverage by the intermediates of both processes. The anomalous behaviour of the Tafel coefficient, b , as a function of temperature was attributed to surface adsorption of the electrolyte species, and the competition between them, as well as gas bubble adherence. Comparison of the current efficiencies of the EOP, F EOP , determined for different temperatures and supporting electrolyte compositions, showed the presence of fluorinated anions increases F EOP . The influence of the anion nature on F EOP , when analysed in the light of the proposed electrode mechanism, reveals introduction into the electrolyte of anions having a high electronegativity changes the double layer structure resulting in an increase of surface concentration of the active centres leading to EOP. The inhibition of the OER in the high overpotential domain during EOP provoked by fluoro-anion adsorption is supported by the activation energy data. In situ surface characterisation before and after EOP investigation revealed that even under drastic conditions (high current density, low interfacial pH) b-PbO 2 can be considered an inert electrode material. #
_Electrochemica Acta, 2003
The nature of the electrolyte strongly influences the electrode kinetics of the oxygen evolution reaction (OER) and electrochemical ozone production (EOP) mainly by affecting the degree of coverage by the intermediates of both processes. The anomalous behaviour of the Tafel coefficient, b , as a function of temperature was attributed to surface adsorption of the electrolyte species, and the competition between them, as well as gas bubble adherence. Comparison of the current efficiencies of the EOP, F EOP , determined for different temperatures and supporting electrolyte compositions, showed the presence of fluorinated anions increases F EOP . The influence of the anion nature on F EOP , when analysed in the light of the proposed electrode mechanism, reveals introduction into the electrolyte of anions having a high electronegativity changes the double layer structure resulting in an increase of surface concentration of the active centres leading to EOP. The inhibition of the OER in the high overpotential domain during EOP provoked by fluoro-anion adsorption is supported by the activation energy data. In situ surface characterisation before and after EOP investigation revealed that even under drastic conditions (high current density, low interfacial pH) b-PbO 2 can be considered an inert electrode material. #
Electrolytic Ozone Generation at Pt/Ti Electrode Prepared by Multiple Electrostrike Method
Chemistry Letters, 2019
Electrochemical ozone generation at an easily prepared platinum-modified titanium electrode was investigated and compared with that at boron-doped diamond (BDD) and Pt electrodes. The Pt/Ti electrode was prepared through our original method, the multiple electrostrike method. The ozone generation ability of the Pt/Ti electrode was much higher than those of BDD and Pt electrodes. This research is expected to contribute to the development of practical electrodes for inexpensive and effective ozone generators.
Electrochemistry and green chemical processes: electrochemical ozone production
Química Nova, 2003
After an introductory discussion emphasising the importance of electrochemistry for the so-called Green Chemical Processes, the article presents a short discussion of the classical ozone generation technologies. Next a revision of the electrochemical ozone production technology focusing on such aspects as: fundamentals, latest advances, advantages and limitations of this technology is presented. Recent results about fundamentals of electrochemical ozone production obtained in our laboratory, using different electrode materials (e.g. boron doped diamond electrodes, lead dioxide and DSA -based electrodes) also are presented. Different chemical processes of interest to the solution of environmental problems involving ozone are discussed.
Green processes for environmental application. Electrochemical ozone production
Pure and Applied Chemistry, 2000
Several aspects of electrochemical ozone production (EOP) on β-PbO 2 were investigated. The morphology of the electrode material was determined in situ using extensive (total, external, and internal differential capacity) and intensive parameters (the morphology factor, ϕ) permitting comparison with results of other laboratories if appropriate electrode characterization parameters are available. The influence of the nature of the supporting electrolyte on the oxygen evolution reaction (OER)/EOP processes was investigated using polarization curves, recorded under quasi-stationary conditions, point-by-point polarization, and chronopotentiometry. The performance of the several β-PbO 2 /electrolyte system was evaluated using the apparent specific power criterion. A detailed mechanism for EOP is proposed.
Development of spin-coated Si/TiOx/Pt/TiOx electrodes for the electrochemical ozone production
Applied Surface Science, 2009
A novel electrode having the compositional sequence Si/TiOx/Pt/TiOx was developed for ozone electrogeneration. The spin-coating method, the sputtering deposition technique, and a post-annealing procedure were all combined to assemble the electrode composition. A two-compartment electrolytic cell separated by a Nafion membrane was used to generate ozone galvanostatically. The X-ray photon electron spectroscopy (XPS) and atomic force microscopy (AFM) were used to reveal the electrode composition and morphology. The influence of several factors including the electrode's annealing temperature, the electrolyte composition, and the electrolysis’ current density on the efficiency of ozone production was investigated. A maximum ozone generation efficiency of 2.5% was obtained at 74 mA cm−2 at room temperature. Interestingly, the electrode preserved (ca. 80%) of its original activity to produce ozone after 50 h of continues electrolysis at 74 mA cm−2 at room temperature.