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Dual‐Function Fluorescent Covalent Organic Frameworks: HCl Sensing and Photocatalytic H 2 Evolution from Water
Author(s) -
ELMahdy Ahmed F. M.,
Elewa Ahmed M.,
Huang ShengWen,
Chou HoHsiu,
Kuo ShiaoWei
Publication year - 2020
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.202000641
Subject(s) - photocatalysis , materials science , fluorescence , photochemistry , solvatochromism , covalent bond , luminescence , crystallinity , solvent , chemistry , organic chemistry , catalysis , optoelectronics , optics , physics , composite material
Two ultrastable luminescent covalent organic frameworks (COFs), PyTA‐BC and PyTA‐BC‐Ph, are synthesized through polycondensations of 4,4′,4″,4′″‐pyrene‐1,3,6,8‐tetrayl)tetraaniline (PyTA‐4NH 2 ) with two carbazole‐based derivatives having different degrees of conjugation. The PyTA‐BC and PyTA‐BC‐Ph COFs exhibit ultrahigh thermal stabilities (up to 421 °C), excellent crystallinity, and high Brunauer–Emmett–Teller surface areas (up to 1445 m 2 g −1 ). These COFs display strong fluorescence emissions in various solvents, with their emission maxima gradually red‐shifting upon increasing the polarity of the solvent (solvatochromism). Upon exposure to HCl, they respond very rapidly and sensitively in terms of changing their colors and fluorescence emission maxima. In the presence of a sacrificial electron donor, these COFs mediate the highly efficient photocatalytic evolution of H 2 from water. In the absence of a noble metal cocatalyst, the COFs and ascorbic acid provide a photocatalytic H 2 production of up to 1183 µmol g −1 h −1 (λ ≥ 420 nm); this value is the highest reported to date for a COF. Such COFs appear to be potentially useful as chemosensors for the naked‐eye and sensitive spectroscopic detection of HCl and as cocatalysts for the sustainable photocatalytic production of H 2 from water.