Anthraquinone-Based Conjugated Organic Polymers Containing Dual Oxidation Centers for Photocatalytic H₂O₂ Production from H₂O and O₂ under Visible-Light Irradiation

Abstract

Photocatalytic H2O2 production from H2O and O2 under visible-light irradiation is a promising method for the green chemical industry and the conversion of solar energy to fuel. However, the efficiencies remain relatively low due to the rapid photogenerated charge recombination caused by the inefficient H2O oxidation. Herein, we present an anthraquinone-based conjugated organic polymer (AQTT-COP) containing alkynyl and triazinyl dual oxidation centers by the Sonogashira cross-coupling reaction of 2,6-dibromoanthraquinone (AQ) and 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine (TT). The dual H2O-oxidation centers of triazinyl and alkynyl moieties are conducive to the consumption of photogenerated holes and inhibit electron–hole pair recombination by efficient H2O-oxidation reactions. Meanwhile, the anthraquinone moieties could serve as O2 reduction centers to accept photogenerated electrons and transfer them to the O2 molecules for the subsequent production of H2O2, thereby boosting the overall reaction kinetics, which in turn improves non-sacrificial H2O2 production. The rational design of AQTT-COP with spatially separated O2 reduction centers and dual H2O-oxidation centers enables maximizing photogenerated electron utilization and exhibits efficient photocatalytic H2O2 production with an initial rate of 3221 μmol g–1 h–1 under visible-light (λ ≥ 400 nm) irradiation without any additives. This work provides a protocol for the unification of task-specific catalytically active components for photocatalytic H2O2 production.

Hexagonal Hollow Porous Organic Framework Nanotubes for Efficient Photocatalytic H2O2 Production in Pure H2O under O2 Atmosphere

“…X-ray photoelectron spectroscopy (XPS) indicates that BPYTEA-POF and BPHTEA-POF possess a C 1s peak at ∼284 eV and an N 1s peak at ∼399 eV (Figure S5). The high-resolution C 1s XPS of BPYTEA-POF shows that it is divided into three binding energy peaks, in which the peak at 286.1 eV corresponds to –CN– in 2,2′-bipyridine, the peak at 285.4 eV corresponds to –CC– in tris­(4-ethylphenyl) amines, and the peak at 284.8 eV corresponds to C–CC in the aromatic ring and adventitious hydrocarbons (Figure e) . As expected, the signal of C 1s derived from carbon atoms adjacent to the pyridine nitrogens of 2,2′-bipyridine moiety was not observed in the high-resolution C 1s XPS of BPHTEA-POF when 2,2′-bipyridine moiety was replaced by 1,1′-biphenyl.…”

“…During the reaction of H 2 O 2 photosynthesis, the photogenerated electrons reduce the oxygen molecule adsorbed on the photocatalyst surface and combine with H + to form H 2 O 2 ; the photogenerated holes react with water molecules to form O 2 and H + ; the generated O 2 and H + are later used to produce H 2 O 2 without sacrificial agents, thus boosting the overall reaction efficiency. , It is worth mentioning that the oxidation of water is the rate-limiting step during the H 2 O 2 preparation by photocatalysis because it needs a higher potential than the reduction of oxygen . The weak H 2 O oxidation remains the main cause of photocatalytic H 2 O 2 generation inefficiency . In order to settle this problem, a lot of research studies have concentrated on promoting POF-based photocatalysts via introducing heteroatoms and/or constructing heterojunction structures, , but the modification of the energy band structure cannot essentially improve the water oxidation efficiency.…”

Leveraging phenazine and dihydrophenazine redox dynamics in conjugated microporous polymers for high-efficiency overall photosynthesis of hydrogen peroxide

“…2d). 5,11,21–34 Meanwhile, TPE-PNZ achieved an impressive SCC efficiency of 0.58%, surpassing most CMP-based photocatalysts reported to date (Table S1†). In contrast, TPE-AC, designed as a comparative benchmark by replacing phenothiazine with anthracene in TPE-PNZ, only exhibited a much lower H 2 O 2 production rate of 2183 μmol g −1 h −1 .…”