Exploring the “Goldilocks Zone” of Semiconducting Polymer Photocatalysts by Donor–Acceptor Interactions

• Published in: Angewandte Chemie International Edition Vol. 57; no. 43; pp. 14188 - 14192
• Main Authors: Kochergin, Yaroslav S., Schwarz, Dana, Acharjya, Amitava, Ichangi, Arun, Kulkarni, Ranjit, Eliášová, Pavla, Vacek, Jaroslav, Schmidt, Johannes, Thomas, Arne, Bojdys, Michael J.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 22-10-2018
• Edition: International ed. in English
• Subjects: Active sites; Catalysis; Catalytic activity; Charge transfer; Chemical synthesis; Chemists; conjugated microporous polymers; Domains; donor–acceptor systems; Energy gap; Fluorescence; fluorescence sensing; Hydrogen-based energy; Hydrophobicity; Optical properties; Organic chemistry; Organic compounds; Photocatalysis; Photocatalysts; Polymers; Porosity; Sulfur; Triazine; VOCs; Volatile organic compounds; Water splitting; conjugated microporous polymers; donor-acceptor systems; photocatalysis; fluorescence sensing; triazine
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201809702

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 band gap of about 2.3 eV, A library of eight sulfur and nitrogen containing porous polymers (SNPs) with similar geometries but with optical band gaps ranging from 2.07 to 2.60 eV was synthesized using Stille coupling. These polymers combine π‐conjugated electron‐withdrawing triazine (C3N3) and electron donating, sulfur‐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.
Just right! A library of eight highly modular, photoactive S‐ and N‐containing porous polymers (SNPs) enabled exploration of the ideal conditions for photocatalytic water splitting. Intrinsic push–pull effects lead to enhanced separation of photo‐induced charge‐carriers and to exquisite control of the band gap, yielding materials with the highest hitherto reported hydrogen evolution rate.