Hydroxyl-Functionalized Covalent Organic Frameworks as High-Performance Supercapacitors

Tzu-Ling Yang; Jhu-You Chen; Shiao-Wei Kuo; Chen-Tsyr Lo; Ahmed F M El-Mahdy

doi:10.3390/polym14163428

Hydroxyl-Functionalized Covalent Organic Frameworks as High-Performance Supercapacitors

Polymers (Basel). 2022 Aug 22;14(16):3428. doi: 10.3390/polym14163428.

Authors

Tzu-Ling Yang¹, Jhu-You Chen¹, Shiao-Wei Kuo¹, Chen-Tsyr Lo², Ahmed F M El-Mahdy^{1

3}

Affiliations

¹ Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan.
² Department of Material Science and Engineering, National Taiwan University of Science and Technology, Taipei 10617, Taiwan.
³ Chemistry Department, Faculty of Science, Assiut University, Assiut 71516, Egypt.

Abstract

Covalent organic frameworks (COFs) have attracted significant interest because of their heteroatom-containing architectures, high porous networks, large surface areas, and capacity to include redox-active units, which can provide good electrochemical efficiency in energy applications. In this research, we synthesized two novel hydroxy-functionalized COFs-TAPT-2,3-NA(OH)_2, TAPT-2,6-NA(OH)₂ COFs-through Schiff-base [3 + 2] polycondensations of 1,3,5-tris-(4-aminophenyl)triazine (TAPT-3NH₂) with 2,3-dihydroxynaphthalene-1,4-dicarbaldehyde (2,3-NADC) and 2,6-dihydroxynaphthalene-1,5-dicarbaldehyde (2,6-NADC), respectively. The resultant hydroxy-functionalized COFs featured high BET-specific surface areas up to 1089 m² g^-1, excellent crystallinity, and superior thermal stability up to 60.44% char yield. When used as supercapacitor electrodes, the hydroxy-functionalized COFs exhibited electrochemical redox activity due to the presence of redox-active 2,3-dihydroxynaphthalene and 2,6-dihydroxynaphthalene in their COF skeletons. The hydroxy-functionalized COFs showed specific capacitance of 271 F g^-¹ at a current density of 0.5 A g^-¹ with excellent stability after 2000 cycles of 86.5% capacitance retention. Well-known pore features and high surface areas of such COFs, together with their superior supercapacitor performance, make them suitable electrode materials for use in practical applications.

Keywords: Schiff-base; covalent organic frameworks; dihydroxynaphthalene; redox-active; supercapacitors.

Grants and funding

This study was supported financially by the Ministry of Science and Technology, Taiwan, under contracts MOST 108-2218-E-110-013-MY3, 110-2636-E-110-009, and 111-2221-E-110-003.