Surface electrochemistry and electrocatalytic activity of ion pairs formed from oppositely-charged phthalocyanine and porphyrin species

2007 ◽  
Vol 11 (03) ◽  
pp. 151-159 ◽  
Author(s):  
Junsheng Chen ◽  
A. B. P. Lever
Keyword(s):  
Electrochemical Properties ◽  
Electrode Surface ◽  
Electrocatalytic Activity ◽  
Electrocatalytic Oxidation ◽  
Graphite Electrode ◽  
Ion Pairs ◽  
Oxalate Anion ◽  
Surface Electrochemistry ◽  
The Individual ◽  
Oppositely Charged

Self-assembled ion pairs are deposited onto a graphite electrode surface by dipping the electrode sequentially into phthalocyanine cations and anions, or a phthalocyanine cation and porphyrin anion. The electrochemical properties of these surface-bound ion pairs are compared with the properties of the individual surface-bound components. The order of deposition is shown to be crucial, implying that these species lie flat on the surface. A detailed study of the electrocatalytic oxidation of oxalate anion is used to explore their reactivity as a function of deposition order.

Surface electrochemistry of N,N',N″,N‴-tetramethyl-tetra-3,4-pyridinoporphyrazinocobalt(II)

2006 ◽  
Vol 10 (10) ◽  
pp. 1238-1248 ◽  
Author(s):  
Junsheng Chen ◽  
Jiujun Zhang ◽  
Yu-Hong Tse ◽  
Pavel Janda ◽  
Dharamdat Christendat ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Electrocatalytic Activity ◽  
Positive Charge ◽  
Graphite Electrode ◽  
Cobalt Phthalocyanine ◽  
Central Metal ◽  
Spontaneous Reduction ◽  
Surface Electrochemistry ◽  
Peroxide Reduction ◽  
Concerted Processes

The complex N,N',N″,N‴ -tetramethyl-tetra-3,4-pyridinoporphyrazinocobalt(II) ([ Co II TMPz [4+])4+ adsorbed on a graphite electrode undergoes spontaneous reduction, forming a surface containing Co I. Five reversible surface peaks are observed at low pH, two of which are two-electron concerted processes. At high pH, one of these two-electron processes splits into two one-electron waves. Both oxidation and reduction of the central metal can be observed, along with successive reduction steps involving the porphyrazine ligand. Notable is the marked shift to positive potentials of these processes, relative to unsubstituted cobalt phthalocyanine, due to the positive charge localized on the porphyrazine. The electrocatalytic activity of this complex modified electrode toward the reduction of hydrogen peroxide is also reported. We demonstrate that a series of different surfaces exist which are obtained by variation of pH and polarization potential and that these surfaces possess differing electrocatalytic activity. Surfaces inactive to hydrogen peroxide can exist at potentials more negative than active surfaces even though the driving force for peroxide reduction will be greater for the former.

The Phase Structure and Electrochemical Properties of La4MgNi19-xCox(x=0～2) Hydrogen Storage Alloys

2014 ◽  
Vol 875-877 ◽  
pp. 277-281 ◽  
Author(s):  
Huan Huan Lu ◽  
Fan Song Wei ◽  
Fan Na Wei
Keyword(s):  
Phase Composition ◽  
Corrosion Rate ◽  
Electrochemical Properties ◽  
Electrode Surface ◽  
Electrocatalytic Activity ◽  
Phase Structure ◽  
Electrochemical Measurement ◽  
High Rate ◽  
Cyclic Stability ◽  
Hydrogen Storage Alloys

The influence of substitution Co for Ni on the phase structure and electrochemical properties of La4MgNi19 phase composition alloys have been investigated systematically.The structure analyses show that the alloys are mainly composed of multiphase,such as CaCu5 phase ,Pr5Co19 phase and Ce5Co19 phase.The electrochemical measurement showed that alloy electrodes could be activated in 2-3 cycles, with increasing of x value, the maximum discharge capacity gradually increased from 345.7 mA·h/g (x = 0.0) to 382.8 mA·h/g (x = 2.0), cyclic stability increased a little ,but high-rate dischargeability (HRD) decreased somewhat. It is found that the HRD was mainly controlled by the electrocatalytic activity on the alloy electrode surface,and the improvement of cyclic stability was due to the increase of CaCu5 phase and Ce5Co19 phase . CaCu5 phase increased with increasing Co content. Ce5Co19 phase has a small corrosion rate in the electrochemical cycle.

Enhancing the electrocatalytic activity of CoO for the oxidation of 5-hydroxymethylfurfural by introducing oxygen vacancies

2020 ◽  
Vol 22 (3) ◽  
pp. 843-849 ◽  
Author(s):  
Xin Huang ◽  
Jinliang Song ◽  
Manli Hua ◽  
Zhenbing Xie ◽  
Shuaishuai Liu ◽  
...  
Keyword(s):  
Electrocatalytic Activity ◽  
Electrocatalytic Oxidation ◽  
Oxygen Vacancies ◽  
Se Doping ◽  
Furandicarboxylic Acid

The activity of CoO for the electrocatalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid could be significantly enhanced by introducing oxygen vacancies via Se doping.

scholarly journals Selective Determination of Dopamine in Presence of Ascorbic Acid Using Nafion Coated Methylene Blue Functionalized Graphite Electrode

2019 ◽  
Vol 31 (10) ◽  
pp. 2185-2190
Author(s):  
G. Sivasankari ◽  
K. Sivasankari ◽  
T. Nalini ◽  
P. Padmapriya ◽  
M. Nadhiya
Keyword(s):  
Methylene Blue ◽  
Ascorbic Acid ◽  
Modified Electrode ◽  
Electrode Surface ◽  
Graphite Electrode ◽  
Low Cost ◽  
Differential Pulse ◽  
Selective Determination ◽  
The Stability

An electrochemical sensor has been developed using methylene blue (MB) unctionalized graphite for the selective determination of dopamine in the presence of ascorbic acid. The immobilization of methylene blue on graphite was done by carbodiimide coupling method. The methylene blue functionalized graphite was characterized by SEM, FTIR spectroscopy and UV-visible spectroscopy. The immobilization of methylene blue functionalized graphite (MB-G) on the electrode surface was made by drop casting a small volume of MB-G dispersed methanol solution on the electrode surface. About 5 L of 0.5 % Nafion solution was also dropcasted for the stability and selectivity. The MB-G modified electrode was characterized by cyclic voltammetry. The modified electrode promotes the electrocatalytic oxidation of dopamine at a lower potential of 160 mV. The selective determination of dopamine in the presence of 100 times higher concentration of ascorbic acid was achieved by differential pulse voltammetry. The modified electrode offered a simple, selective and sensitive determination of low levels of dopamine. Also the oxidation over potential was reduced to an extent of 360 mV comparing with the bare graphite electrode. The proposed sensor has the advantage of easy fabrication, low cost, good sensitivity, reproducibility and stability.

Electrocatalytic oxidation of water by a self-assembled oxovanadium(iv) complex modified gold electrode

2015 ◽  
Vol 5 (12) ◽  
pp. 5100-5104 ◽  
Author(s):  
Koushik Barman ◽  
Sk Jasimuddin
Keyword(s):  
Water Oxidation ◽  
Electrocatalytic Activity ◽  
Gold Electrode ◽  
Electrocatalytic Oxidation ◽  
Neutral Ph ◽  
Self Assembled

An oxovanadium(iv) complex modified gold electrode showed efficient electrocatalytic activity towards water oxidation at neutral pH.

Electrocatalytic activity of a graphite electrode coated with hexadecachlorophthalocyanatoiron(II) toward sulfide oxidation, and its possible application in electroanalysis

1995 ◽  
Vol 73 (7) ◽  
pp. 1072-1077 ◽  
Author(s):  
Jiujun Zhang ◽  
A.B.P. Lever ◽  
W.J. Pietro
Keyword(s):  
Electrocatalytic Activity ◽  
Graphite Electrode ◽  
Sulfide Oxidation ◽  
Ion Concentration ◽  
Cyclic Voltammograms ◽  
Peak Current ◽  
Sulfide Ion ◽  
Concentration Dependences ◽  
Basic Solutions ◽  
Ph Range

A graphite electrode coated with hexadecachlorophthalocyanatoiron(II), FeII[Cl16Pc(2-)], serves as an electrocatalyst for the oxidation of sulfide ion in basic solutions (pH range: 8–14). The surface electrochemical responses of this catalyst and corresponding electrocatalytic activity are discussed. The sulfide ion concentration dependences of the peak current in cyclic voltammograms are examined to show the possible application of this catalyst-coated electrode in amperometric sulfide sensors. Keywords: phthalocyanine, modified graphite electrode, sulfide oxidation, electroanalysis, electrocatalysis.

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