Electrocatalytic properties of a dinuclear cobalt(III) coordination compound in molecular oxygen reduction reaction

Abstract

A new dinuclear cobalt(III) coordination compound, [Co 2 L(μ-N 3 )(N 3 ) 2 ]Á CH 3 OH (1), was synthesized and characterized by elemental analysis, spectroscopic methods, and single-crystal X-ray analysis in which H 3 L is a heptadentate ligand obtained by the condensation of triethylenetetramine with 5-bromo-2-hydroxybenzaldehyde. X-ray analysis revealed that two cobalt(III) ions have distorted octahedral geometry and are connected together by a phenoxy and an azide bridging ligand. The catalytic activity of compound 1 for oxygen (O 2 ) reduction reaction was investigated. Compound 1 can efficiently catalyze the reduction of O 2 by a weak electron donor, ferrocene (Fc), at the polarized water-1,2-dichloroethane interface. It was found that compound 1 can catalyze O 2 reduction to H 2 O 2 , whereas in the presence of Fc, it can catalyze the reduction of O 2 to water. K E Y W O R D Sdinuclear cobalt(III) coordination compound, ferrocene, liquid-liquid interface, oxygen reduction reaction

Hydrogen Evolution, Oxygen Evolution, and Oxygen Reduction at Polarizable Liquid|Liquid Interfaces

“…[128] On the basis of the comparison of voltammetric data collected at TFT j H 2 O interface at different pH the stronger electrocatalytic effect of Au nanoparticles in alkaline solution was noted. [117] ORR in a biphasic system consisting the same phases separated by bulk gold was demonstrated as an example of bipolar biphasic electrochemical system. [129] External polarisation of micro liquid j liquid interface formed by Pt nanoparticles aqueous suspension in contact with Fc and hydrophobic electrolyte solution in TFT produces current spikes ascribed to ORR catalytic enhancement due to individual collisions of nanoparticles with interface.…”

“…Fe(II) phtalocyanine (FePc) also exhibits catalytic activity at DCE|H 2 O interface with DFc and TTF as electron donor and ORR follows 4 electron path, but reaction is extremely slow [114] . Other macrocyclic mono‐, [115,116] bi‐, [117] and tetranuclear [118] Co(III) complexes with Schiff base ligands were employed as catalyst for biphasic ORR at DCE|H 2 O with Fc as electron donor. Biphasic catalytic generation of H 2 O 2 with Cu(II) protonated linear polymer and Fc or TTF has to be noted [119] …”

“…Charging of Au film provides additional driving force and formation of superoxide anion further reacting with protons to generate H 2 O 2 is the rate‐determining step [128] . On the basis of the comparison of voltammetric data collected at TFT|H 2 O interface at different pH the stronger electrocatalytic effect of Au nanoparticles in alkaline solution was noted [117] . ORR in a biphasic system consisting the same phases separated by bulk gold was demonstrated as an example of bipolar biphasic electrochemical system [129] …”

Electrocatalytic reduction of Molecular Oxygen with a Copper (II) Coordination Polymer

“…The catalytic effect of porphyrin, [5] Schiff base complex [18] and various ligands [19][20][21] on the oxygen reduction by various organic electron donors at the water/DCE interface have also been investigated. Complexes of Cu such as laccase [22,23] and cytochrome oxidase [24] as natural complexes of copper have also been used as catalyst for ORR.…”