2,1,3-Benzothiadiazole-Spaced Co-Porphyrin-Based Covalent Organic Frameworks for O2 Reduction

Bhunia, S and Peña-Duarte, A and Li, H and Li, H and Sanad, MF and Saha, P and Addicoat, MA and Sasaki, K and Strom, TA and Yacamán, MJ and Cabrera, CR and Seshadri, R and Bhattacharya, S and Brédas, J-L and Echegoyen, L (2022) 2,1,3-Benzothiadiazole-Spaced Co-Porphyrin-Based Covalent Organic Frameworks for O2 Reduction. In: ACS Nano .

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Abstract

Designing N-coordinated porous single-atom catalysts (SACs) for the oxygen reduction reaction (ORR) is a promising approach to achieve enhanced energy conversion due to maximized atom utilization and higher activity. Here, we report two Co(II)-porphyrin/ [2,1,3]-benzothiadiazole (BTD)-based covalent organic frameworks (COFs; Co@rhm-PorBTD and Co@sql-PorBTD), which are efficient SAC systems for O2 electrocatalysis (ORR). Experimental results demonstrate that these two COFs outperform the mass activity (at 0.85 V) of commercial Pt/C (20%) by 5.8 times (Co@rhm-PorBTD) and 1.3 times (Co@sql-PorBTD), respectively. The specific activities of Co@rhm-PorBTD and Co@sql-PorBTD were found to be 10 times and 2.5 times larger than that of Pt/C, respectively. These COFs also exhibit larger power density and recycling stability in Zn-air batteries compared with a Pt/C-based air cathode. A theoretical analysis demonstrates that the combination of Co-porphyrin with two different BTD ligands affords two crystalline porous electrocatalysts having different d-band center positions, which leads to reactivity differences toward alkaline ORR. The strategy, design, and electrochemical performance of these two COFs offer a pyrolysis-free bottom-up approach that avoids the creation of random atomic sites, significant metal aggregation, or unpredictable structural features.

Item Type:	Journal Article
Publication:	ACS Nano
Publisher:	American Chemical Society
Additional Information:	The copyright for this article belongs to American Chemical Society.
Keywords:	Atoms; Cobalt compounds; Coordination reactions; Electrocatalysis; Electrocatalysts; Electrolytic reduction; Oxygen; Zinc air batteries, Alkaline oxygen reduction; Alkalines; Benzothiadiazole based; Benzothiadiazoles; Covalent organic frameworks; Donor/acceptor; Oxygen Reduction; Porphyrin-benzothiadiazole; Porphyrinic framework, Porphyrins
Department/Centre:	Division of Chemical Sciences > Organic Chemistry
Date Deposited:	25 Feb 2023 08:33
Last Modified:	25 Feb 2023 08:33
URI:	https://eprints.iisc.ac.in/id/eprint/80708

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