Carbon Nanotubes with Cobalt Corroles for Hydrogen and Oxygen Evolution in pH 0–14 Solutions

Li, Xialiang; Lei, Haitao; Liu, Jieyu; Zhao, Xuechao; Ding, Shuping; Zhang, Zongyao; Tao, Xixi; Zhang, Wei; Wang, Weichao; Zheng, Xiaohong; Cao, Rui

doi:10.1002/ange.201807996

Cited by 33 publications

(11 citation statements)

References 62 publications

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“…To graft the azide-containing Co corrole 1 onto CNTs through covalent bonds, CNTs were first functionalized with 4-ethynylaniline to introduce surface alkyne groups. 79,82 The as-prepared alkynefunctionalized CNTs were denoted as CNT-alkyne hereafter. Notably, iron powder used in this synthesis was carefully removed by stirring the products in hydrochloric acid and then washing with ethanol, acetone, and water.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Co corroles were synthesized according to the method we reported previously. 79 All aqueous solutions were prepared freshly using the Milli-Q water. Multiwalled CNTs (>95% purity, <8 nm outside diameter, 3 nm intside diameter) were commercially available.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Recently, we reported the covalent immobilization of azidecontaining Co corroles onto alkyne-modified CNTs through azide−alkyne cycloaddition. 79 CNTs are chosen as the support for electrocatalysis due to their good electrical conductivities and large surface areas. 80 With the use of this method, we can graft Co corrole 1 onto CNTs (Figure 1).…”

Section: ■ Introductionmentioning

confidence: 99%

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Attaching Cobalt Corroles onto Carbon Nanotubes: Verification of Four-Electron Oxygen Reduction by Mononuclear Cobalt Complexes with Significantly Improved Efficiency

et al. 2019

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Cobalt complexes have been extensively explored in catalyzing the oxygen reduction reaction (ORR), which is the cathode reaction in fuel cells. Although they show high activities, mononuclear Co complexes typically mediate the 2e reduction of O 2 to H 2 O 2 , and two Co sites are generally required to catalyze the 4e reduction of O 2 to H 2 O. Herein we report the significantly improved efficiency of covalently grafted Co corroles on carbon nanotubes (CNTs) for the 4e ORR. Azide-containing Co corroles can be attached to alkyne-modified CNTs via azide−alkyne cycloaddition. This attachment can avoid the formation of dimeric face-to-face Co corroles. The resulted hybrid catalyzes the 4e ORR in 0.5 M H 2 SO 4 aqueous solutions with a half-wave potential at 0.78 V versus reversible hydrogen electrode (RHE). This performance makes this hybrid one of the most efficient Co-based molecular ORR electrocatalysts. Control studies using Co corrole analogues loaded on CNTs via noncovalent interactions give ORR half-wave potentials at 0.68−0.61 V versus RHE. This work is significant in demonstrating that with proper covalent bond interactions to CNTs mononuclear Co corroles can become intrinsically active for the 4e ORR with significantly improved efficiency.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Attaching Cobalt Corroles onto Carbon Nanotubes: Verification of Four-Electron Oxygen Reduction by Mononuclear Cobalt Complexes with Significantly Improved Efficiency

et al. 2019

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“…34,35 The electron transfer rate between the molecular catalyst and the electrode can be changed by using a specific type of linker and therefore also influences the catalytic performance. 36 A covalent binding of the catalyst to the SAM can be realized in different ways, but the use of the "click" reaction to give a triazole ring is a straightforward method to attach, for example, an imidazole unit that can axially coordinate to a porphyrin. The reduction of aryldiazonium salts is another common approach to covalently attach a linker unit to the electrode directly or MWCNTs.…”

Section: ■ Introductionmentioning

confidence: 99%

Influence of Mesityl and Thiophene Peripheral Substituents on Surface Attachment, Redox Chemistry, and ORR Activity of Molecular Iron Porphyrin Catalysts on Electrodes

Götz

Wrzolek

et al. 2019

Inorg. Chem.

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Two iron porphyrin complexes with either mesityl (FeTMP) or thiophene (FeT3ThP) peripheral substituents were attached to basal pyrolytic graphite and Ag electrodes via different immobilization methods. By combining cyclic voltammetry and in-operando surface-enhanced Raman spectroscopy along with MD simulations and DFT calculations, their respective surface attachment, redox chemistry and activity toward electrocatalytic oxygen reduction was investigated. For both porphyrin complexes, it could be shown that catalytic activity is restricted to the first (few) molecular layer(s), although electrodes covered with thiophene-substituted complexes showed a better capability to consume the oxygen at a given overpotential even in thicker films. The spectroscopic data and simulations suggest that both porphyrin complexes attach to a Ag electrode surface in a way that maximum planarity and minimum distance between the catalytic iron site and the electrode is achieved. However, due to the distinctive design of the FeT3ThP complex, the thiophene rings are capable of occupying a conformation, via rotation around the bonding axis to the porphyrin, in which all four sulfur atoms can coordinate to the Ag surface. This effect creates a dense and planar surface coverage of the porphyrin on the electrode facilitating a fast (multi) electron transfer via several covalent Ag–S bonds. In contrast, bulky mesityl groups as peripheral substituents, which have been initially introduced to prevent aggregation and improve catalytic behavior in solution, exert a negative effect on the overall electrocatalytic performance in the immobilized state as a less dense coverage and less stable interactions with the surface are formed. Our results underline the importance of rationally designed heterogenized molecular catalysts to achieve optimal turnover, which not only strictly applies to the here discussed oxygen reduction reaction but eventually holds also true for other energy conversion reactions such as carbon dioxide reduction.

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“…Very recently, Cao and co-workers developed the covalent immobilization of Co corroles on CNTs and investigated the effects of different immobilization methods on HER and OER. 194 The azido-containing Co corrole 72 was grafted to CNTs via covalent bonds to make hybrids H1 and H2 (Figure 23). As shown in this figure, Co corrole 72 can be covalently attached to CNTs with short conjugated linkers in H1 or with long alkane chains in H2.…”

Section: Immobilization Of Molecular Catalystmentioning

confidence: 99%

Structure Effects of Metal Corroles on Energy-Related Small Molecule Activation Reactions

et al. 2019

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The increasing global energy and environmental crises make it urgent to find and use renewable, clean, and environmentally benign new energy resources. New energy conversion schemes based on small molecule activation reactions, including hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR), have been proposed. For example, catalytic water splitting provides a promising way to convert solar energy to chemical energy, which is stored as the hydrogen fuel. Hydrogen oxidation in fuel cells is an energy-releasing process to generate electric energy and water as the only product. Although such a hydrogen-based new energy scheme is appealing, its viability is dependent on highly efficient and robust catalysts for these small molecule activation reactions. Recently, a variety of metal corroles have been demonstrated to be efficient in catalyzing HER, OER, and ORR. The redoxactive trianionic corrole ligands can afford a rigid four-coordinated square-planar molecular structure and are very effective in stabilizing high-valent metal centers. These features make metal corroles very attractive to serve as catalysts for these processes. More importantly, the structure of metal corroles can be systematically modified, which provides an ideal system to investigate the structure−reactivity relationship with aims to obtain fundamental knowledge on catalyst design and also catalytic mechanism. In this review, we summarize recently reported metal corrole catalysts for HER, OER, and ORR, as well as pay particular attention to the structure effects on these reactions.

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Carbon Nanotubes with Cobalt Corroles for Hydrogen and Oxygen Evolution in pH 0–14 Solutions

Cited by 33 publications

References 62 publications

Attaching Cobalt Corroles onto Carbon Nanotubes: Verification of Four-Electron Oxygen Reduction by Mononuclear Cobalt Complexes with Significantly Improved Efficiency

Attaching Cobalt Corroles onto Carbon Nanotubes: Verification of Four-Electron Oxygen Reduction by Mononuclear Cobalt Complexes with Significantly Improved Efficiency

Influence of Mesityl and Thiophene Peripheral Substituents on Surface Attachment, Redox Chemistry, and ORR Activity of Molecular Iron Porphyrin Catalysts on Electrodes

Structure Effects of Metal Corroles on Energy-Related Small Molecule Activation Reactions

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