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Wang Q, Wang C, Zheng K, Wang B, Wang Z, Zhang C, Long X. Positional Thiophene Isomerization: A Geometric Strategy for Precisely Regulating the Electronic State of Covalent Organic Frameworks to Boost Oxygen Reduction. Angew Chem Int Ed Engl 2024; 63:e202320037. [PMID: 38348605 DOI: 10.1002/anie.202320037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Indexed: 02/29/2024]
Abstract
With the oxygen conversion efficiency of metal-free carbon-based fuel cells dramatically improved, the building blocks of covalent organic frameworks (COFs) raised principal concerns on the catalytic active sites with indistinct electronic states. Herein, to address this issue, we demonstrate COFs for oxygen reduction reaction (ORR) by regulating the edge-hanging thiophene units, and the molecular geometries are further modulated via positional thiophene isomerization strategy, affording isomeric COF-α with 2-substitution and COF-β with 3-substitution on the frameworks. The electronic states and intermediate adsorption ability are well-regulated through geometric modification, resulting in controllable chemical activity and local density of π-electrons. Notably, the introduction of thiophene units with different substitution positions into a pristine pure carbon-based COF model COF-Ph achieves excellent activity with a half-wave potential of 0.76 V versus the reversible hydrogen electrode, which is higher than most of those metal-free or metal-based electrocatalysts. Utilizing the combination of theoretical prediction and in situ Raman spectra, we show that the isomeric thiophene skeleton (COF-α and COF-β) can induce the dangling unit activation, accurately identifying the pentacyclic-carbon (thiophene α-position) adjacent to sulfur atom as active sites. The results suggest that the isomeric dangling groups in COFs are suitable for the ORR with promising geometry construction.
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Affiliation(s)
- Qian Wang
- State Key Laboratory of Bio-fibers and Eco-textiles, Collaborative Innovation Center of Shandong Marine Biobased Fibers and Ecological textiles, Institute of Marine Biobased Materials, College of Materials Science and Engineering, Qingdao University, Qingdao, 266071, P. R. China
| | - Chao Wang
- State Key Laboratory of Bio-fibers and Eco-textiles, Collaborative Innovation Center of Shandong Marine Biobased Fibers and Ecological textiles, Institute of Marine Biobased Materials, College of Materials Science and Engineering, Qingdao University, Qingdao, 266071, P. R. China
| | - Kunpeng Zheng
- State Key Laboratory of Bio-fibers and Eco-textiles, Collaborative Innovation Center of Shandong Marine Biobased Fibers and Ecological textiles, Institute of Marine Biobased Materials, College of Materials Science and Engineering, Qingdao University, Qingdao, 266071, P. R. China
| | - Binbin Wang
- State Key Laboratory of Bio-fibers and Eco-textiles, Collaborative Innovation Center of Shandong Marine Biobased Fibers and Ecological textiles, Institute of Marine Biobased Materials, College of Materials Science and Engineering, Qingdao University, Qingdao, 266071, P. R. China
| | - Zhong Wang
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, P. R. China
| | - Chuanhui Zhang
- State Key Laboratory of Bio-fibers and Eco-textiles, Collaborative Innovation Center of Shandong Marine Biobased Fibers and Ecological textiles, Institute of Marine Biobased Materials, College of Materials Science and Engineering, Qingdao University, Qingdao, 266071, P. R. China
| | - Xiaojing Long
- State Key Laboratory of Bio-fibers and Eco-textiles, Collaborative Innovation Center of Shandong Marine Biobased Fibers and Ecological textiles, Institute of Marine Biobased Materials, College of Materials Science and Engineering, Qingdao University, Qingdao, 266071, P. R. China
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Fu G, Yang D, Xu S, Li S, Zhao Y, Yang H, Wu D, Petkov PS, Lan ZA, Wang X, Zhang T. Construction of Thiadiazole-Bridged sp 2-Carbon-Conjugated Covalent Organic Frameworks with Diminished Excitation Binding Energy Toward Superior Photocatalysis. J Am Chem Soc 2024; 146:1318-1325. [PMID: 38181378 DOI: 10.1021/jacs.3c08755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2024]
Abstract
Sp2-carbon-conjugated covalent organic frameworks (sp2c-COFs) have emerged as promising platforms for phototo-chemical energy conversion due to their tailorable optoelectronic properties, in-plane π-conjugations, and robust structures. However, the development of sp2c-COFs in photocatalysis is still highly hindered by their limited linkage chemistry. Herein, we report a novel thiadiazole-bridged sp2c-COF (sp2c-COF-ST) synthesized by thiadiazole-mediated aldol-type polycondensation. The resultant sp2c-COF-ST demonstrates high chemical stability under strong acids and bases (12 M HCl or 12 M NaOH). The electro-deficient thiadiazole together with fully conjugated and planar skeleton endows sp2c-COF-ST with superior photoelectrochemical performance and charge-carrier separation and migration ability. As a result, when employed as a photocathode, sp2c-COF-ST exhibits a significant photocurrent up to ∼14.5 μA cm-2 at 0.3 V vs reversible hydrogen electrode (RHE) under visible-light irradiation (>420 nm), which is much higher than those analogous COFs with partial imine linkages (mix-COF-SNT ∼ 9.5 μA cm-2) and full imine linkages (imi-COF-SNNT ∼ 4.9 μA cm-2), emphasizing the importance of the structure-property relationships. Further temperature-dependent photoluminescence spectra and density functional theory calculations demonstrate that the sp2c-COF-ST has smaller exciton binding energy as well as effective mass in comparison to mix-COF-SNT and imi-COF-SNNT, which suggests that the sp2c-conjugated skeleton enhances the exciton dissociation and carrier migration under light irradiation. This work highlights the design and preparation of thiadiazole-bridged sp2c-COFs with promising photocatalytic performance.
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Affiliation(s)
- Guangen Fu
- Key Laboratory of Marine Materials and Related Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
| | - Denghui Yang
- State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou 350108, China
| | - Shunqi Xu
- Center for Advancing Electronics Dresden (CFAED) and Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Dresden 01062, Germany
| | - Shengxu Li
- Key Laboratory of Marine Materials and Related Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
| | - Yuxiang Zhao
- Key Laboratory of Marine Materials and Related Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
| | - Haoyong Yang
- Key Laboratory of Marine Materials and Related Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
| | - Daheng Wu
- Key Laboratory of Marine Materials and Related Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
| | - Petko Stoev Petkov
- Faculty of Chemistry and Pharmacy, University of Sofia, Sofia 1164, Bulgaria
| | - Zhi-An Lan
- State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou 350108, China
| | - Xinchen Wang
- State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou 350108, China
| | - Tao Zhang
- Key Laboratory of Marine Materials and Related Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
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