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Exploring the “Goldilocks Zone” of Semiconducting Polymer Photocatalysts via Donor-Acceptor Interactions

preprint
submitted on 02.05.2018, 10:28 and posted on 02.05.2018, 14:52 by Yaroslav S. Kochergin, Dana Schwarz, Amitava Acharjya, Arun Ichangi, Ranjit Kulkarni, Pavla Eliášová, Jaroslav Vacek, Johannes Schmidt, Arne Thomas, Michael J. Bojdys
Water splitting using polymer photocatalysts is a key technology to a truly sustainable hydrogen-based energy economy. Synthetic chemists have intuitively tried to enhance photocatalytic activity by tuning the length of π-conjugated domains of their semiconducting polymers, but the increasing flexibility and hydrophobicity of ever-larger organic building blocks leads to adverse effects such as structural collapse and inaccessible catalytic sites. To reach the ideal optical bandgap of ~2.3 eV, we synthesised a library of eight sulphur and nitrogen containing porous polymers (SNPs) with similar geometries but with optical bandgaps ranging from 2.07 to 2.60 eV using Stille coupling. These polymers combine π-conjugated electron-withdrawing triazine- (C3N3) and electron donating, sulphur-containing moieties as covalently-bonded donor-acceptor frameworks with permanent porosity. The remarkable optical properties of SNPs enable fluorescence on-off sensing of volatile organic compounds and illustrate intrinsic charge-transfer effects. Moreover, obtained polymers effectively evolve H2 gas from water under visible light irradiation with hydrogen evolution rates up to 3158 µmol h-1 g-1 and high apparent quantum efficiency which is the highest value obtained for microporous organic polymers to-date. The design principles demonstrated here are transferable to a new field of high-performance polymer photocatalysts based on efficient donor-acceptor dyads.

Funding

European Research Council (BEGMAT-678462), German Science Foundation (Project TH1463/15-1), Cluster of Excellence (UniCat)

History

Email Address of Submitting Author

m.j.bojdys.02@cantab.net

Email Address(es) for Other Author(s)

yaroslav.kochergin@uochb.cas.cz amitava-_acharjya5@mailbox.tu-berlin.de ichangia@natur.cuni.cz ranjit.kulkarni@uochb.cas.cz pavla.eliasova@natur.cuni.cz vacek@uochb.cas.cz johannes.schmidt@tu-berlin.de arne.thomas@tu-berlin.de

Institution

Humbold-Universität zu Berlin, Department of Chemistry

Country

Germany

ORCID For Submitting Author

0000-0002-2592-4168

Declaration of Conflict of Interest

No conflict of interest.

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