The search for metal-free organic photocatalysts for H2 production from water using visible light remains a key challenge. Reported herein is a molecular structural design of pure organic photocatalysts, derived from conjugated polybenzothiadiazoles, for photocatalytic H2 evolution using visible light. By alternating the substitution position of the electron-withdrawing benzothiadizole unit on the phenyl unit as a comonomer, various polymers with either one- or three-dimensional structures were synthesized and the effect of the molecular structure on their catalytic activity was investigated. Photocatalytic H2 evolution efficiencies up to 116 μmol h(-1) were observed by employing the linear polymer based on a phenyl-benzothiadiazole alternating main chain, with an apparent quantum yield (AQY) of 4.01 % at 420 nm using triethanolamine as the sacrificial agent.
The formation of
aldehydes and ketones via selective oxidation
of alcohols is an essential transformation in organic synthesis. However,
the usually harsh reaction conditions using toxic metal catalysts
or corrosive reagents lead to undesired side products and wastes.
Environmentally friendly and mild reaction conditions using metal-free
catalysts remain a huge challenge. Herein, we report the use of a
thiophene-based covalent triazine framework (CTF) as pure organic
and visible-light-active photocatalyst for the selective oxidation
of alcohols at room temperature. Molecular oxygen was activated as
a clean and selective oxidant. The high selectivity and efficiency
of the pure organic photocatalyst could be demonstrated and were comparable
to those of the state-of-art metal or nonmetal catalytic systems reported.
Pure organic, heterogeneous, metal-free,
and visible light-active
photocatalysts offer a more sustainable and environmentally friendly
alternative to traditional metal-based catalysts. Here we report a
series of microporous organic polymers containing photoactive conjugated
organic semiconductor units as heterogeneous photocatalysts for a
visible-light-promoted, highly selective bromination reaction of electron-rich
aromatic compounds using HBr as a bromine source and molecular oxygen
as a clean oxidant. Via a simple Friedel–Crafts alkylation
reaction, the microporous organic polymers were obtained by cross-linking
of organic semiconductor compounds with defined valence and conduction
band positions. The utilization of the simply prepared porous polymer-based
photocatalytic systems opens new opportunities toward a sustainable
and efficient material design for catalysis.
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