Spectroelectrochemical Investigation of Pentacarbonyl(pyrazine)metal(0) (Metal = Cr, Mo, W) Complexes of Group 6 Elements

2002 ◽  
Vol 57 (1) ◽  
pp. 92-98 ◽  
Author(s):  
Şeniz Özalp Yaman ◽  
Emren Esentürk ◽  
Ceyhan Kayran ◽  
Ahmet M. Önal
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Behaviour ◽  
Reference Electrode ◽  
Constant Current ◽  
Oxidation Peak ◽  
Group 6 ◽  
Constant Potential ◽  
Electrochemical Mechanism ◽  
Temperature Constant

The electrochemical behaviour of pentacarbonyl(pyrazine)metal(0) complexes of the group 6 elements was studied by cyclic voltammetry in dichloromethane-(n-Bu)4NBF4 solventelectrolyte couple at -20°C vs. Ag/Ag+ or SCE reference electrode. Constant potential electrolyses of the complexes were carried out at their first oxidation peak potentials and monitored in situ by UV-Vis spectrometry. Electrolysis of W(CO)5pz produces [W(CO)5pz]+ and a similar electrochemical mechanism is expected both for Cr(CO)5pz and Mo(CO)5pz complexes. In situ low temperature constant current ESR electrolysis also confirmed the production of [W(CO)5pz]+ after the electron transfer.

Spectro-Electrochemistry of Diethyldithiocarbamate Complexes of Ni(II), Pd(II) and Pt(II)

2001 ◽  
Vol 56 (2) ◽  
pp. 202-208 ◽  
Author(s):  
Şeniz Özalp Yaman ◽  
Ahmet M. Önal ◽  
Hiüseyin Isci
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Oxidation ◽  
Room Temperature ◽  
Electrochemical Behaviour ◽  
Reference Electrode ◽  
Electrochemical Process ◽  
Oxidation Peak ◽  
Complex Species ◽  
Constant Potential

Abstract The electrochemical behaviour of Na(Et2NCS2) and M(Et2NCS2)2 (M= Ni(II), Pd(II) and Pt(II); Et2NCS2-= diethyldithiocarbamate) as studied by cyclic voltammetry in the acetonitrile-( n-Bu)4NBF4 solvent-electrolyte couple at room temperature vs. Ag/Ag+ reference electrode. Constant potential electrolyses of the complexes were carried out at their first oxidation peak potentials and monitored in situ by UV-VIS spectrophotometry. The electrolysis of Ni(Et2NCS2)2 in solution yielded the dimer of the ligand, (Et2NCS2)2, and Ni2+(sol) as final products. During this electrochemical process the formation of a Ni(III) complex species as an intermediate has been observed. The electrochemical oxidation of bis(diethyldithiocarbamato) complexes of Pd(II) and Pt(II) yielded [Pd(Et2NCS2)3]+ and [Pt(Et2NCS2)3]+, respectively.

In situ detection of intermediates from the interaction of dissolved sulfide and manganese oxides with a platinum electrode in aqueous systems

2017 ◽  
Vol 14 (3) ◽  
pp. 178 ◽  
Author(s):  
Yao Luo ◽  
Yougang Shen ◽  
Lihu Liu ◽  
Jun Hong ◽  
Guohong Qiu ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Manganese Oxides ◽  
Platinum Electrode ◽  
Aqueous Systems ◽  
Oxidation Peak ◽  
Peak Current ◽  
Oxidation Peak Current ◽  
Dissolved Sulfide ◽  
In Situ Detection

Environmental contextDissolved sulfide results in soil acidification and subsequent contaminant leaching via oxidation processes, usually involving manganese oxides. In this work, redox processes were monitored in situ by cyclic voltammetry and HS– concentrations were semi-quantitatively determined. The method provides qualitative and semi-quantitative assessment for dissolved sulfide and its oxidation intermediates in aqueous systems. AbstractDissolved sulfide can be oxidised by manganese oxides in supergene environments, while the intermediates including S0, S2O32– and SO32– are easily oxidised by oxygen in air, resulting in some experimental errors in conventional analyses. In this work, the electrochemical behaviours of HS–, S2O32– and SO32– on a platinum electrode were studied by cyclic voltammetry and constant potential electrolysis, and in situ detection of the intermediates was conducted in aqueous systems of HS– and manganese oxides. The results showed that HS– was first oxidised to S0, and then transformed to SO42–. The peak current for the oxidation of HS– to S0 had a positive linear correlation with the used starting HS– concentration. S2O32– and SO32– were directly electrochemically oxidised to SO42–. The oxidation current peak potentials at 0, 0.45 and 0.7V were respectively observed for HS–, S2O32– and SO32– at pH 12.0. Cyclic voltammetry was conducted to monitor the redox processes of HS– and manganese oxides. The oxidation peak current of HS– to S0 decreased, and that of S2O32– to SO42– was observed to increase as the reaction proceeded. The rate of the decrease of the oxidation peak current of HS– indicated that the oxidation activity followed the order of birnessite>todorokite>manganite.

Electrochemical behaviour of lanthanum fluoride in molten fluorides

2008 ◽  
Vol 62 (6) ◽  
Author(s):  
Marta Ambrová ◽  
Jana Jurišová ◽  
Vladimír Danielik
Keyword(s):  
Cyclic Voltammetry ◽  
Intermetallic Compounds ◽  
Electrode Materials ◽  
Electrochemical Behaviour ◽  
Reference Electrode ◽  
Eutectic Mixture ◽  
Graphite Crucible ◽  
Lanthanum Fluoride ◽  
Reduction Peak ◽  
Tungsten Electrodes

AbstractThe electrochemical behaviour of lanthanum fluoride dissolved in molten lithium fluoride and in eutectic mixture LiF-CaF2 was investigated by cyclic voltammetry and laboratory electrolysis. The cyclic voltammetry experiments were carried out at 900°C and 800°C, respectively, in a graphite crucible (counter electrode). Several types of working electrodes (Mo, W, Ni and Cu) were used. Ni/Ni(II) was used as a reference electrode. Laboratory electrolysis was carried out in the system LiF-CaF2-LaF3 at 800°C in galvanostatic (j c = −0.21 A cm−2) and potentiostatic (E = 0.87 V) regimes. In both cases, nickel served as the cathode and graphite as the anode. It was found that no new separate reduction peak occurred on the molybdenum or tungsten electrodes in the investigated systems. When copper or nickel electrodes were used, new peaks corresponding to the reduction of lanthanum(III) to lanthanum metal appeared. This can be explained by the formation of alloys or intermetallic compounds of lanthanum with copper or nickel. X-ray microanalysis showed that lanthanum was electrodeposited together with calcium under formation of intermetallic compounds with the electrode materials in the galvanostatic regime. In the potentiostatic regime, mainly lanthanum was deposited, which enabled its separation.

Electrochemical Study of Tricarbonyl(η6-cyclooctatetraene)metal(0) Complexes of the Group 6 Elements

1998 ◽  
Vol 53 (8) ◽  
pp. 875-880
Author(s):  
Giirkan Atinç Yilmaz ◽  
Ahmet M. Önal ◽  
Saim Özkar
Keyword(s):  
Cyclic Voltammetry ◽  
Nmr Spectroscopy ◽  
Supporting Electrolyte ◽  
Energy Levels ◽  
Dichloromethane Solution ◽  
Reduction Potentials ◽  
Ir And Nmr Spectroscopy ◽  
Group 6 ◽  
Constant Potential ◽  
Uv Visible

Abstract Tricarbonyl(η6-cyclooctatetraene)metal(0) complexes of the group 6 elements were prepared by using the procedures described in the literature with some minor modifications and identi­fied by IR and NMR spectroscopy. Their electrochemical behavior was studied by using cyclic voltammetry in dichloromethane solution containing 0.1 M tetrabutylammonium tetrafiuorob-orate as supporting electrolyte. Their oxidation and reduction potentials were measured and discussed in terms of the frontier energy levels in connection with the UV-Visible electronic ab­ sorption spectral data. In order to elucidate the mechanism of electrooxidation of the complexes, constant potential electrolysis was performed for one representative example, tricarbonyl(η6-cyclooctatetraene)chromium(O). The IR monitoring of the reaction showed that it is gradually converted to hexacarbonylchromium(O) upon electrolysis at constant potential.

Electrochemical behaviour of silver in aqueous chromate solutions

1998 ◽  
Vol 76 (8) ◽  
pp. 1156-1161 ◽  
Author(s):  
Sayed S Abd El Rehim ◽  
Magdy AM Ibrahim ◽  
Hamdy H Hassan ◽  
Mohammed A Amin
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Behaviour ◽  
Anode Surface ◽  
Cyclic Voltammograms ◽  
Oxidation Peak ◽  
Surface Layers ◽  
Compact Layer ◽  
X Ray ◽  
Solid Films ◽  
Scan Rate

The electrochemical behaviour of silver was studied under cyclic voltammetry and chronoamperometry conditions in aqueous K2CrO4 solutions. The forward cyclic voltammograms exhibited one oxidation peak, A1, due to the formation of Ag2CrO4. The height of the anodic peak, A1, increases with increasing chromate concentration, temperature, and scan rate. The solid films formed on the anode surface have been examined by X-ray diffractometry. The reverse voltammograms exhibited two reduction peaks, C1 and C2, indicating the formation of two distinct surface layers of Ag2CrO4, an inner compact layer reduced in peak C1 and an outer powdery layer reduced in peak C2.Key words: silver electrode, cyclic voltammetry, K2CrO4 solutions.

scholarly journals Electrochemical Performance of ABNO for Oxidation of Secondary Alcohols in Acetonitrile Solution

Molecules ◽  
2018 ◽  
Vol 24 (1) ◽  
pp. 100 ◽  
Author(s):  
Pengfei Niu ◽  
Xin Liu ◽  
Zhenlu Shen ◽  
Meichao Li
Keyword(s):  
Cyclic Voltammetry ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Electrocatalytic Oxidation ◽  
Room Temperature ◽  
Electrochemical Activity ◽  
Constant Current ◽  
Acetonitrile Solution ◽  
Secondary Alcohols

The ketones was successfully prepared from secondary alcohols using 9-azabicyclo[3.3.1]nonane-N-oxyl (ABNO) as the catalyst and 2,6-lutidine as the base in acetonitrile solution. The electrochemical activity of ABNO for oxidation of 1-phenylethanol was investigated by cyclic voltammetry, in situ Fourier transform infrared spectroscopy (FTIR) and constant current electrolysis experiments. The resulting cyclic voltammetry indicated that ABNO exhibited much higher electrochemical activity when compared with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) under the similar conditions. A reasonable reaction mechanism of the electrocatalytic oxidation of 1-phenylethanol to acetophenone was proposed. In addition, a series of secondary alcohols could be converted to the corresponding ketones at room temperature in 80–95% isolated yields.

Anodic reactions of sulphate in molten salts

2010 ◽  
Vol 64 (1) ◽  
Author(s):  
Marta Ambrová ◽  
Pavel Fellner ◽  
Jomar Thonstad
Keyword(s):  
Cyclic Voltammetry ◽  
Sodium Fluoride ◽  
Electrochemical Behaviour ◽  
Anodic Process ◽  
Third Wave ◽  
Anodic Wave ◽  
Molten Sodium ◽  
Working Electrode ◽  
Anodic Reactions

AbstractElectrochemical behaviour of sulphate under anodic polarization in molten sodium chloride, cryolite and sodium fluoride was investigated by cyclic voltammetry and chronopotentiometry at the temperatures of 820°C, 1010°C, and 1000°C, respectively. Using a platinum working electrode, two waves were observed on the chronopotentiograms in the systems: NaCl-Na2SO4 and Na3AlF6-Na2SO4. The first wave was attributed to the formation of oxygen. The second wave probably originated from the reaction of oxygen with platinum, or from oxidation of SO3 decomposition products. Three waves were observed for the anodic process of sulphate ions dissolved in molten sodium fluoride. The first wave was attributed to the formation of oxygen. The second and the third wave were attributed to the formation of PtO and PtO2. This conclusion was supported by cyclic voltammetry experiments of the in-situ formed sulphide in molten NaCl at 820°C and by chronopotentiometry on a gold working electrode in the system NaCl-Na2SO4, where no anodic wave was observed.

scholarly journals In-Situ Electrochemical Behaviour of Biocathode Microbial Fuel Cell (MFC)

2020 ◽  
Author(s):  
S. Venkata Ramana ◽  
Cristina M. Cordas ◽  
Sara C. Matias ◽  
Luis Joaquim Pina da Fonseca
Keyword(s):  
Cyclic Voltammetry ◽  
Fuel Cell ◽  
Electrochemical Reduction ◽  
Microbial Fuel Cell ◽  
Electrochemical Behaviour ◽  
Redox Processes ◽  
Experimental Conditions ◽  
Microbial Cells ◽  
Electrochemical Reduction Of Oxygen

Abstract In the present work the electrochemical behaviour of microbial cells from a biocathode microbial fuel cell (MFC) functioning with wastewater was evaluated by cyclic voltammetry. In-situ electrochemical assays were performed and, under the tested experimental conditions, the biocathode medium was found to be the most efficient for the cathodic catalysed electrochemical reduction of oxygen. Different controls using sterile media and membranes covering the electrodes were performed and compared with the regular biocathode results. In the biocathode chamber, the presence of bacteria was associated with the enhanced active redox processes and with the higher electrochemical reduction of oxygen activity. The present study is a contribution to the understanding of the viability and advantages of the biocathodes use in MFC.

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