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Substrate Curvature-Induced Regulation of Charge Distribution of Covalent Organic Frameworks Promotes Capacitive Deionization
Summary:
The authors from Nagoya University and other institutions developed a covalent organic framework (COF) material with regulated charge distribution by using curved carbon nanotubes (CNTs) as substrates, achieving ultrahigh ion adsorption capacity in capacitive deionization applications.
Background:
1. To address the challenge of limited intrinsic conductivity and ion adsorption capacity of conventional COFs, previous researchers focused on hybridizing COFs with conductive substrates, achieving some success but still facing limitations in performance.
2. The authors proposed an innovative approach of curvature engineering by using CNTs as substrates to induce local strain and regulate charge distribution within the COF skeleton, resulting in enhanced capacitive deionization performance.
Research Content:
1. Synthesis:
The authors synthesized TpPa-SO3H-COF using the Schiff-base condensation reaction and grew it on CNT and graphene substrates to form hybrid materials.
2. Characterizations:
1) BET results showed specific surface areas of 195.66 m²/g for TpPa-SO3H@CNT-50 and 317.67 m²/g for TpPa-SO3H@Graphene.
2) SEM/TEM tests revealed that TpPa-SO3H-COF formed a core-shell structure around CNTs with fiber-like morphology, while it appeared as plate-like structures on graphene.
3) XPS and FTIR analyses confirmed the presence of active sites for Na+ adsorption, with lower binding energies in TpPa-SO3H@CNT-50 compared to TpPa-SO3H@Graphene.
3. Application:
The material was tested in capacitive deionization applications, achieving an ion (Na+) adsorption capacity of 58.74 mg/g and a salt (NaCl) adsorption capacity of 149.25 mg/g in 1000 ppm NaCl solution at 1.2 V.
4. Mechanism:
Theoretical calculations and XPS analysis revealed that substrate curvature induced local strain, lowering the binding energy state of adsorption sites and facilitating Na+ adsorption. EQCM measurements further confirmed faster Na+ adsorption kinetics in the curved COF structure.
Outlook:
This research demonstrates the significance of curvature engineering in enhancing the performance of COFs for capacitive deionization, providing new insights for designing high-performance COF-based materials.
Substrate Curvature-Induced Regulation of Charge Distribution of Covalent Organic Frameworks Promotes Capacitive Deionization
Authors: Dong Jiang, Ruibo Xu, Liang Bai, Jonathan P. Hill, Joel Henzie, Liyang Zhu, Wei Xia, Ran Bu, Yingji Zhao, Yunqing Kang, Takashi Hamada, Renzhi Ma, Nagy Torad, Jie Wang, Toru Asahi, Xingtao Xu, and Yusuke Yamauchi
DOI: 10.1002/adfm.202407479
Link: https://onlinelibrary.wiley.com/doi/10.1002/adfm.202407479
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