Electrochemical and Electron Paramagnetic Resonance Study of the Mechanism of Oxidation of Phenazine-di-N-oxide in the Presence of Isopropyl alcohol at Glassy Carbon and Single-Walled Carbon Nanotube Electrodes

Comparative Electrochemical and Electron Paramagnetic Resonance Study of the Mechanism of Oxidation of 2,3,5,6-Tetra-Me-Pyrazine-Di-N-Oxide as a Mediator of Electrocatalytic Oxidation of Methanol at Glassy Carbon and Multi-Walled Carbon Nanotube Paper Electrodes

“…The effect of addition of CH3COOH and water (as a base) on the potential of catalytic wave and catalytic current of Pyr2 oxidation at GC and MWCNT paper electrodes in the presence of MeOH show that the catalytic process is accompanied by proton elimination. Similar effect of addition of CH3COOH and of H2O on catalytic oxidation of PhenDNO and Pyr2 in the presence of i-PrOH at GC and SWCNT paper electrodes observed earlier studies [48,49]. Based on the obtained experimental data, the oxidation of Pyr2 in the presence of MeOH at the GC electrode can be explained by the E1C1E2C2 mechanism proposed earlier [1][2][3][4][5][6][7][8][9] for the two- The next chemical stage (C2) corresponds to the interaction of the cation with a nucleophile or base (a water admixture in the solution).…”

“…If we assume that the change in the entropy of the system during the formation of the adsorption complexes of PhenDNO and ferrocene with the surface of CNT electrode is approximately the same in the two cases, the concentration of PhenDNO on the surface is ≈ 30 times higher than that of ferrocene at low values of surface coverage. As in the case of PhenDNO oxidation [47,48], the increase of the current of Pyr2 oxidation at SWCNT [49] and MWCNT paper electrodes (found in this work) by several times as compared with that for ferrocene can be explained by Pyr2 adsorption which results in the increase of Pyr2 concentration on the electrode surface and, as a consequence, in the increase of its oxidation current.…”

“…Therefore, it was reasonable to study the possibility of using such electrodes in the processes of electrocatalytic oxidation of organic compounds in the presence of electrochemically generated aromatic di-N-oxide radical cation. We studied the mechanism of oxidation of PhenDNO in the presence of cyclohexanol [47] and PhenDNO and Pyr2 in the presence isopropyl alcohol (i-PrOH) [48,49] by the methods of cyclic voltammetry, EPR electrolysis and the differential capacitance at GC and SWCNT paper (produced in our institute [47] and produced by "NanoLab's" firm (USA) [48,49]) electrodes in 0.1 M LiClO4 solutions in acetonitrile. It was found that the catalytic efficiency of oxidation of organic compounds at SWCNT electrodes in the presence of aromatic di-N-oxide increases several times as compared with oxidation at GC electrode.…”

Electrochemical and quantum chemical studies of peculiarities of 2,5-di-Me-pyrazine-di-N-oxide oxidation in the presence of methanol at single-walled and multi-walled carbon nanotube paper electrodes

“…In previous studies, [16][17][18][19] in the presence of aromatic di-Noxide, a several-fold increase in the catalytic efficiency of oxidation of organic compounds at SWCNT or MWCNT paper electrodes in comparison with the GC electrode was found. It was noted [16][17][18][19] that in the absence of the substrate the oxidation current of phenazine-di-N-oxide, 2,3,5,6-tetra-Me-pyrazine-di-Noxide, at SWCNT or MWCNT paper electrodes is by several times higher than the oxidation current of the ferrocene (Fc) reference.…”

“…In previous studies, [16][17][18][19] in the presence of aromatic di-Noxide, a several-fold increase in the catalytic efficiency of oxidation of organic compounds at SWCNT or MWCNT paper electrodes in comparison with the GC electrode was found. It was noted [16][17][18][19] that in the absence of the substrate the oxidation current of phenazine-di-N-oxide, 2,3,5,6-tetra-Me-pyrazine-di-Noxide, at SWCNT or MWCNT paper electrodes is by several times higher than the oxidation current of the ferrocene (Fc) reference. Quantum chemical modeling of the adsorption energies of Pyr 1 , Fc and MeCN both on the CNT surface and in grooves between two CNTs using the cluster model simulating the surface of conducting and non-conducting carbon nanotubes 20 can explain this effect.…”