Bio-inspired multinuclear copper complexes covalently immobilized on reduced graphene oxide as efficient electrocatalysts for the oxygen reduction reaction

Abstract

Inspired by the multicopper active site of laccase, which efficiently catalyzes the oxygen reduction reaction (ORR), herein we report a novel bio-inspired ORR catalyst composed of a multinuclear copper complex that was immobilized on the surface of reduced graphene oxide (rGO) via the covalently grafted triazole-dipyridine (TADPy) dinucleating ligand. This rGO-TADPyCu catalyst exhibited high ORR activity and superior long-term stability compared to Pt/C in alkaline media.

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

“…It is now instructive to compare the onset potential for oxygen reduction by MWCNT-supported 1 (+ 0.60 Vv s. RHE) with values published for other immobilized copper complexes.I ti sc lose to the redox potentials observed for immobilized galactose oxidase (+ 0.72 Vv s. RHE) [13] and some mononuclear copper complexes involving sterically hindered ligands immobilized in carbon black/nafion ink (+ 0.60 and + 0.67 Vv s. RHE), [22] but much lower than what was measured for dicopper catalysts based on (tris(2-pyridylmethyl)amine) ligands (+ 0.86 Vv s. RHE) or reducedgraphene-oxide-supported multicopper/triazole-dipyridine complexes (+ 0.95 V). [23] This supports the involvement of amononuclear species in the ORR in our case.Inthis sense, immobilized complex 1 acts as ag alactose oxidase mimic by achieving the 2e À /1 H + reduction of O 2 into aC u II -OOH intermediate, [3] but it is also able to achieve the reduction of…”

From Enzymes to Functional Materials—Towards Activation of Small Molecules

“…[191] Similar results were reported when dicopper triazole-dipyridine-dichloride (TADPyCu) was immobilized on graphene oxide surfaces. [192] Notably,w hile this material facilitated the reduction to H 2 O, the absence of Cu lead to production of > 60 %H 2 O 2 and showcases the importanceo faCu center in the control of electron transfer.T he use of imidazoles as potential proton relay platformsi so fa dvantage for ORR and was also shown with 5-nitrophenanthroline-based Cu complexes on MWCNTs. The utilization of imidazoles as linkers of metalstoa nelectrode support generally enhanced the catalytic activity throughafaster electron transfer and ac loser arrangemento ft he copperc enters on the surface.…”

Covalently Modified Graphenes in Catalysis, Electrocatalysis and Photoresponsive Materials

“…In one of the reported examples, a copper dichloride complex (Scheme a) with a triazole pyridine has been covalently grafted onto rGO and multi‐wall CNTs . The ligand was anchored to the G sheet in two steps, the first one involving the reaction of ethynyl aryldiazonium on the C=C of G, followed by a click reaction of the terminal C≡CH triple bond with 2‐(azido‐methyl pyridine) leading to the triazole pyridine ligand that was finally complexed with Cu II .…”