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Regulating Charge‐Transfer in Conjugated Microporous Polymers for Photocatalytic Hydrogen Evolution
Author(s) -
Mothika Venkata Suresh,
Sutar Papri,
Verma Parul,
Das Shubhajit,
Pati Swapan K.,
Maji Tapas Kumar
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201805478
Subject(s) - photochemistry , materials science , acceptor , photocatalysis , fluorenone , band gap , polymer , conjugated microporous polymer , conjugated system , microporous material , absorption (acoustics) , chemistry , optoelectronics , organic chemistry , fluorene , physics , composite material , condensed matter physics , catalysis
Bandgap engineering in donor–acceptor conjugated microporous polymers (CMPs) is a potential way to increase the solar‐energy harvesting towards photochemical water splitting. Here, the design and synthesis of a series of donor–acceptor CMPs [tetraphenylethylene (TPE) and 9‐fluorenone (F) as the donor and the acceptor, respectively], F 0.1 CMP , F 0.5 CMP , and F 2.0 CMP , are reported. These CMPs exhibited tunable bandgaps and photocatalytic hydrogen evolution from water. The donor–acceptor CMPs exhibited also intramolecular charge‐transfer (ICT) absorption in the visible region ( λ max =480 nm) and their bandgap was finely tuned from 2.8 to 2.1 eV by increasing the 9‐fluorenone content. Interestingly, they also showed emissions in the 540–580 nm range assisted by the energy transfer from the other TPE segments (not involved in charge‐transfer interactions), as evidenced from fluorescence lifetime decay analysis. By increasing the 9‐fluorenone content the emission color of the polymer was also tuned from green to red. Photocatalytic activities of the donor–acceptor CMPs ( F 0.1 CMP , F 0.5 CMP , and F 2.0 CMP ) are greatly enhanced compared to the 9‐fluorenone free polymer ( F 0.0 CMP ), which is essentially due to improved visible‐light absorption and low bandgap of donor–acceptor CMPs. Among all the polymers F 0.5 CMP with an optimum bandgap (2.3 eV) showed the highest H 2 evolution under visible‐light irradiation. Moreover, all polymers showed excellent dispersibility in organic solvents and easy coated on the solid substrates.