Anodic Transfer Research Articles

Electrochemical and Kinetic studies for the Degradation of Salicylaldehyde in Non –Aqueous Media

In this study, the electro-oxidation of salicylaldehyde (SA) was investigated in non aqueous media at different scan rate on a platinum electrode by eco friendly cyclic voltammetry (CV) technique. Kinetic and electrochemical parameters were evaluated and reported in terms of standard heterogeneous rate constant (k0 , 6.115×102 s-1), anodic electron transfer rate constant (kox, 1.540×103 s-1), electron transfer coefficient of reaction (α, 0.197), formal potential (E0,1.989 V), and linearity under the influence of scan rate.

Enhanced photocatalytic activity of graphene/TiO2 nanotubes composites prepared by wet transfer method

To enhanced photocatalytic activity of TiO2 nanotubes, graphene was transferred on the surface of TiO2 nanotubes by wet transfer method. The results showed that the introduction of graphene reduced the band gap of composites and inhibited the recombination of photoinduced electrons and holes. Therefore, the degradation rate of the graphene/TiO2 nanotubes composites is about 44% higher than that of the TiO2 nanotubes. It was proved that the photoinduced holes play an important role in the degradation process of methylene blue by trapping experiments. This work provides a new pathway for preparing semiconducting TiO2 based catalysts with enhanced photocatalytic activity. Highlights The graphene/TiO2 nanotubes composites were prepared by simple anodic oxidation and wet transfer method, which is convenient for large-scale production. The introduction of graphene can effectively reduce the band gap and inhibit the recombination of photoinduced electrons and holes. The photocatalytic performance of graphene/TiO2 nanotubes composites is obviously higher than that of TiO2 nanotubes. The results of trapping experiments showed that the photoinduced holes play an important role in the degradation of methylene blue.

Efficient PL Emission from p-type Porous Silicon: A Comparative Study for Selection of Effective Anodization Parameters

The physical mechanism of highly efficient photoluminescence (PL) emission from p-type silicon is described by a comparative study of the effectiveness of the etching parameters in an electrochemical anodization technique. Two series of porous silicon samples were prepared in a combination of anodization current and time, to maintain the total amount of anodic charge transfer constant. Photoluminescence studies show that irrespective of the amount of charge transfer, the samples prepared with comparatively higher current density show an efficient PL as well as stronger blueshift in the emission energy vis-a-vis the samples prepared for longer durations. An overall decrease in crystallite size, as estimated by Raman spectral analysis, was observed for both series of samples with the progress of charge transfer. Comparative analysis shows a marginal difference in crystallite size for both series of samples in the initial state of charge transfer, whereas major differences arise at higher values. This is explained with the formation of silicon suboxide on the porous surface at higher current density, leading to initiation of side wall reaction, and higher reduction rate in crystallite size as well as strong luminescence due to the carrier quantum confinement effect.

Dual kinetic curves in reversible electrochemical systems

We introduce dual kinetic chronoamperometry, in which reciprocal relations are established between the kinetic curves of electrochemical reactions that start from symmetrical initial conditions. We have performed numerical and experimental studies in which the kinetic curves of the electron-transfer processes are analyzed for a reversible first order reaction. Experimental tests were done with the ferrocyanide/ferricyanide system in which the concentrations of each component could be measured separately using the platinum disk/gold ring electrode. It is shown that the proper ratio of the transient kinetic curves obtained from cathodic and anodic mass transfer limited regions give thermodynamic time invariances related to the reaction quotient of the bulk concentrations. Therefore, thermodynamic time invariances can be observed at any time using the dual kinetic curves for reversible reactions. The technique provides a unique possibility to extract the non-steady state trajectory starting from one initial condition based only on the equilibrium constant and the trajectory which starts from the symmetrical initial condition. The results could impact battery technology by predicting the concentrations and currents of the underlying non-steady state processes in a wide domain from thermodynamic principles and limited kinetic information.

Increasing power generation of microbial fuel cells with a nano-CeO2 modified anode

ABSTRACTNano-CeO2 was used to modify the carbon felt anode in microbial fuel cell (MFC). The MFC with the modified anode obtained the higher closed circuit voltage resulting from the lower anode potential, the higher maximum power density (2.94 W m−2), and the lower internal resistance (77.1 Ω). Cyclic voltammetry (CV) results implied that the bioelectrochemical activity of exoelectrogens was promoted by nano-CeO2. Electrochemical impedance spectroscopy (EIS) results revealed that the anodic charge transfer resistance of the MFC decreased with modified anode. This study demonstrates that the nano-CeO2 can be an effective anodic catalyst for enhancing the power generation of MFC.

Effect of Anodic Mass Transfer in the Electrowinning of Copper in Presence of Organic Compounds

Effect of Anodic Mass Transfer in the Electrowinning of Copper in Presence of Organic Compounds

Kinetic study of effect of amine based corrosion inhibitor in reducing corrosion rate of 1018 carbon steel in seawater solution

The effect of an amine based inhibitor (CORTRON AR-505) on the corrosion of 1018 carbon steel in seawater was studied using weight loss, adsorption isotherm analysis, polarisation resistance and potentiodynamic polarisation techniques. AR-505 is adsorbed on the steel surface according to the Shawabkeh–Tutunji adsorption isotherm equation. A maximum adsorption capacity of 0·097 mg AR-505 was obtained to cover a monolayer of adsorption. Corrosion kinetics illustrated that inhibition efficiency has increased with increasing inhibitor concentration and solution pH, while it decreased with increasing solution temperature and stirring speed. Polarisation data fitted by the Butler–Volmer equation showed that the values of anodic and cathodic transfer coefficients are in the average of 0·84 and 0·15 respectively. Corrosion resistance measurements provided a rapid decrease in corrosion rate from 7 to 1 mm/year.

Corrosion of Copper Nuclear Waste Containers In Aqueous Sulphide Solutions

AbstractElectrochemical and surface analytical techniques are being used to determine the mechanismand kinetics of Cu corrosion in the presence of sulphide, with the primary goal of developing a mixed potential model for Cu corrosion under disposal conditions. Corrosion potential (Ecorr) measurements indicate the formation of copper sulphide films is rapid leading to rate control by the cathodic reduction of water. Impedance spectroscopy suggests the anodic charge transfer process is rapid leading to film growth limited by diffusive transport. Experiments are underway to determine the current-potential relationships necessary in the development of a mixed potential model.

Polarization phenomena at the metal/proton conducting electrolyte interphase

The electrokinetics at the H2 - Pd/SrCe0.95Yb0.05O3−α interphase are presented. Current-overpotential (I-η) curves were obtained at 400–700 °C and at hydrogen partial pressures from 1 kPa to 100 kPa, using a three electrode single chamber cell. The present data were assumed to be free of mass transfer effects. The anodic and cathodic charge transfer coefficients as well as the exchange current density were calculated from the experimental results by using the Butler-Volmer equation. The high and low field approximations were used to simplify the analysis.

What anodic and chemical stability for 2-thienyl carbinol ethers? Polymerization and/or cleavage?

The electrochemical and chemical properties of the title compounds 1 have been investigated. It was shown that either anodic electron transfer or lithium cation electrophilic assistance may induce elimination and therefore yield relevant vinylic compounds. Under such conditions, when conducted in the presence of a lithium salt, the anodic polymerization may occur either on 1 (and yield afterward to elimination at the oligomer state) or on the vinylic products. Similar conclusions may appear from 1 radical cations which can afford elimination reactions.

Problems of Anodic and Cathodic Mass Transfer in Copper Refining Electrolysis with Increased Current Density

AbstractFundamental problems of the impact of an increased current density on the conditions of mass transfer at the anode and the cathode are first discussed with special emphasis on the theoretical considerations of diffusion, natural convection and forced convection. An improved electro-chemical measurement technique using probe-type micro electrodes was employed to determine the Cu2+ concentration distribution in the boundary layers at the anode and the cathode. In the case of slime-covered anodes electrolyte sampling was carried out by means of capillaries introduced through bores. Resume Cet article discute des problemes fondamentaux associes a l’impact de l'augmentation de la densite de courant sur les conditions de transfert de matiere a l'anode et a la cathode, en insistant particulierement sur les considerations theoriques de la diffusion et de la convexion (naturelle et forcee). Une technique amelioree de mesure electrochimique, utilisant des microelectrodes de type sonde, a ete employee pour d...

ChemInform Abstract: Electroreductive “Barbier Type” Allylation of Imines with a Combination of a Pb(0)/Pb(II) Redox Mediator and Sacrificial Anode (Al).

Abstract An electroreductive “ Barbier Type ” allylation of imines with allyl bromide has been performed in a PbBr 2 /Bu 4 NBr/THF-(Al anode)-(Pt cathode) system. A combination of Pb(0)/Pb(II) redox and a sacrificial aluminum anode works as a mediator for both cathodic and anodic electron transfer processes, respectively.