Covalent Grafting of Carbon Nanotubes with a Biomimetic Heme Model Compound To Enhance Oxygen Reduction Reactions

Abstract

The oxygen reduction reaction (ORR) is one of the most important reactions in both life processes and energy conversion systems. The replacement of noble‐metal Pt‐based ORR electrocatalysts by nonprecious‐metal catalysts is crucial for the large‐scale commercialization of automotive fuel cells. Inspired by the mechanisms of dioxygen activation by metalloenzymes, herein we report a structurally well‐defined, bio‐inspired ORR catalyst that consists of a biomimetic model compound—an axial imidazole‐coordinated porphyrin—covalently attached to multiwalled carbon nanotubes. Without pyrolysis, this bio‐inspired electrocatalyst demonstrates superior ORR activity and stability compared to those of the state‐of‐the‐art Pt/C catalyst in both acidic and alkaline solutions, thus making it a promising alternative as an ORR electrocatalyst for application in fuel‐cell technology.

Robust electrografted interfaces on metal oxides for electrocatalysis – an in situ spectroelectrochemical study

“…This compares well to the best previously reported onset potentials of 922 and 913 mV (vs RHE) for axial-pyridine coordinated iron phthalocyanine 19 , or axial-imidazole coordinated iron porphyrin immobilised on CNTs, respectively. 20 Other studies on carbon electrodes have reported onset potentials of 820 mV and 880 mV. 76,77 Considering the low loading of catalyst present in the herein presented me-ATO system (3.5 μg/cm 2 of FePOMe), which is about two orders of magnitude less than the loadings employed in the aforementioned systems (between 200 μg/cm 2 and 1 mg/cm 2 ), the obtained onset potential compare well with results from literature.…”

“…Aryl diazonium salts have been widely used to functionalise a range of electrode materials via chemical or electrochemical grafting (electrografting), including carbon materials [19][20][21][22][23][24] , metals 25 , and semiconductors like silicon 26 . Electrografting is a particularly powerful and versatile technique, often resulting in very strong covalent bonds between the electrode substrate and the modifier.…”

Cobalt modified two-dimensional polypyrrole synthesized in a flat nanoreactor for the catalysis of oxygen reduction

“…The best electrocatalyst used for this reaction is the Pt-based material Favilla et al, 2013;Liu et al, 2004); but the limited supply and prohibitive cost of Pt greatly impede the large-scale applications of these renewable energy technologies (Ding et al, 2013;Wu et al, 2011;Xie et al, 2014). Recent attentions gradually move to develop non-precious ORR catalysts, such as transition metal oxides (Andersen et al, 2015;Liang et al, 2011), heteroatom-doped carbon (Inamdar et al, 2013;Yang et al, 2014), and metal-N 4 materials (Kruusenberg et al, 2013;Wei et al, 2014).…”

Fe–N-Doped Mesoporous Carbon with Dual Active Sites Loaded on Reduced Graphene Oxides for Efficient Oxygen Reduction Catalysts

“…Second, the specific surface area and porous structure, which determine the mass transfer during the reaction process and hence the accessible part of the active sites. [8][9][10] In order to obtain such highly efficient ORR electrocatalysts, various non-precious metal catalysts have been developed, including transition-metal-coordinating macrocyclic compounds, 11 pyrolyzed metal/nitrogen/carbon (M-N/C) catalysts, 12,13 metal oxides and chalcogenides, [14][15][16] and heteroatom-doped carbon materials. 17,18 Amongst these, the M-N/C(M=Fe, Co, etc.)…”