Electrocatalytic O₂ Reduction at a Bio‐inspired Mononuclear Copper Phenolato Complex Immobilized on a Carbon Nanotube Electrode

Abstract

An original copper-phenolate complex, mimicking the active center of galactose oxidase,featuring apyrene group was synthesized. Supramolecular pi-stacking allows its efficient and soft immobilization at the surface of aM ulti-Walled Carbon Nanotube (MWCNT) electrode.T his MWCNT-supported galactose oxidase model exhibits a4 H + /4 e À electrocatalytic activity towards oxygen reduction at aredox potential of 0.60 Vv s. RHE at pH 5.

A Nanotube-Supported Dicopper Complex Enhances Pt-free Molecular H2/Air Fuel Cells

“…In addition, the high DE p value of 100 mV at slow scan rates suggests an electrochemically induced structural rearrangement of the copper coordination sphere, similar to other surface-confined copper complexes. 29,38 The inset of Figure 2A shows that the potential of the partially reversible redox system decreases with increasing pH. This dependence is well modeled using Equation 1 39,40 :…”

“…This indicates a rate-determining step corresponding to the 2e À reduction of a coordinated O 2 complex to form a coordinated hydroperoxo species, possibly through a Cu 2 O 2 adduct. 26,28,29,38 Above pH 8, increased maximum current densities were observed for [Cu 2 (BPMP-pyrene)]/ MWCNT electrode, reaching 9.8 (G2) mA cm À2 . This confirmed that optimal ORR activity of this type of complex occurs in basic conditions.…”

“…[23][24][25][26][27][28] Mononuclear copper complexes also proved active for ORR in acidic conditions. In this regard, we have recently shown that a mononuclear copper complex based on the sterically hindered tripodal ligand HMeBMP tBu -pyrene 29 mimicking galactose oxidase's active site, catalyzes ORR at onset potentials close to the enzymes. 30 Tyrosinase, bearing a type 3 Cu A -Cu B active site, displays lower overpotential requirements toward ORR compared to galactose oxidase and catalyzes oxygen reduction in water at onset potentials of 0.60 V versus reversible hydrogen electrode (RHE) (pH 7).…”

Engineering unsymmetrically coordinated Cu-S1N3 single atom sites with enhanced oxygen reduction activity

“…4d and Supplementary Figs. 51 and 52) indicated that the valence of Cu species decreased from approximately +2 to +1, implying that Cu (+1) sites might work as the active centers for ORR 66,67 . When the applied potential returned from 0.75 V to 1.05 V, Cu XANES edge shifted back to higher energy along with increase of the white line peak ( Supplementary Figs.…”

Metal–Organic‐Framework‐Supported Molecular Electrocatalysis for the Oxygen Reduction Reaction

“…Molecular electrocatalysis has gained increasing interests because catalyst structures are clear and can be systematically modified. [1][2][3][4][5][6][7][8][9][10] These features are critical for studying reaction mechanisms and structure-function relationships, which are of fundamental significance for catalyst design. [11][12][13][14][15][16][17][18] Despite these benefits, however, the practical use of molecular electrocatalysis requires immobilization of catalysts on proper supports considering that (1) only those molecules close to electrodes can be activated for reactions with substrates and (2) immobilized catalysts are preferred for reusing and for integrating to electrochemical devices.…”