Effect of non‐covalent interactions in 2,5‐di‐Me‐pyrazine‐di‐N‐oxide ‐ methanol – Carbon nanotube electrocatalytic system

Abstract

Catalytic oxidation of methanol (MeOH) in the absence of noble metals and noble metal oxides as catalysts, and the use of metal‐free materials are inexpensive and attractive process for practical use in electrocatalysis, sensors, and in direct methanol fuel cells. In previous works, it was found that the use of single‐walled (SWCNT) or multi‐walled (MWCNT) carbon nanotube paper electrodes instead of GC increases the catalytic efficiency of organic compounds oxidation in the presence of aromatic di‐N‐oxides by several times. In this work, the effect of non‐covalent interactions on the catalytic efficiency of MeOH oxidation in the presence of 2,5‐di‐Me‐pyrazine‐di‐N‐oxide (Pyr1) in 0.1 M Bu4NClO4 solution in acetonitrile at SWCNT and MWСNT paper electrodes was studied by the methods of quantum chemical modeling, Raman spectroscopy, and using electrochemical data. New factors determined the features of mechanism of MeOH oxidation on CNT electrodes and lead to an increase in the catalytic efficiency of the electrode process in comparison with the GC electrode were established.

Role of non-covalent interactions in 2,5-di-Me-pyrazine-di-N-oxide - tertiary butyl alcohol - single-walled and multi-walled carbon nanotubes electrocatalytic systems

“…These factors lead to an increase in the catalytic efficiency of the process at CNTs electrodes compared to GC electrode. A similar effect was observed in [34] when studying the oxidation of Pyr 1 in the presence of MeOH at SWCNT and MWCNT paper electrodes.…”

“…When using SWCNT or MWCNT paper electrodes instead of GC electrode the catalytic efficiency of organic substrate (cyclohexanol, isopropanol and methanol) oxidation increases by several times [28][29][30][31][32][33][34]. Feature of the electrocatalytic systems studied in our works [28][29][30][31][32][33][34] is the resemblance of the structures of aromatic di-N-oxides and carbon nanotube paper electrodes. This circumstance facilitates adsorption of aromatic di-N-oxides on the surface of CNT paper electrodes.…”

“…Materials, experimental techniques for recording cyclic voltammograms (CVs) and EPR spectra during electrolysis at controlled potentials and quantum chemical modeling techniques were described in detail in our previous works [30][31][32]34].…”

“…Optimization of the geometry of the combined system (model cluster with adsorbed molecules) was carried out at fixed coordinates of the model cluster C 54 H 18 (to preserve the surface shape). The positions of carbon and hydrogen atoms in the cluster are fixed on those obtained from free (10, 10) CNT and only the positions of adsorbed molecules were optimized [32][33][34] on the ωB97XD/6-31G (d,p) level.…”

“…This circumstance facilitates adsorption of aromatic di-N-oxides on the surface of CNT paper electrodes. Quantum chemical modeling of the adsorption of Pyr 1 and Fc (ferrocene) reference [32], components of the catalytic system (Pyr 1 -MeOH-CNT) and Pyr 1 *MeOH complex on CNT surface [33][34] made it possible to explain the effect of increasing the catalytic efficiency of MeOH oxidation at SWCNT and MWCNT paper electrodes in comparison with GC electrode.…”