Regulating molecular structure of donoracceptor (D-A) polymer is a promising strategy to improve photoactivity. Herein, a porous nanorod-like D-A polymer is synthesized via a strategy of supramolecular chemistry combined with subsequent calcination treatment. This polymer consists of benzene rings (D) and triazine (A) that are linked by amido bond (À CONHÀ ). À CONHÀ further partially cracks into cyano groups (À C�N) (A) under calcination. The ratio of benzene to triazine could be tuned to adjust the À C�N content by varying the calcination atmosphere. Such regulation of molecular structure could modulate the band structure of D-A polymer and endow it with unique porous nanorod-like morphology, leading to the achievement of two-electron oxygen reduction and twoelectron water oxidation and the improvement of exciton splitting, O 2 adsorption and activation. These merits synergistically ensure a highly efficient and stable photocatalytic H 2 O 2 production in pure water.

To satisfy the requirements of substantial green development, it is urgent to explore an innovative eco‐friendly semiconductor photocatalyst to efficiently achieve visible‐light‐driven photocatalytic H2 evolution (PHE). The strategy of promoting the spatial separation efficiency of photoinduced carriers can essentially enhance the PHE performance of a photocatalyst. Herein, a graphitic carbon nitride (g‐C3N4)‐based donor–acceptor (D‐A) copolymer (CNDMx) is constructed by simple one‐pot thermal polycondensation, using urea and 5,8‐DibroMoquinoxaline (as an electron donor) as precursors. The electron D‐A modulation consequently creates an internal electric field to facilitate the intramolecular charge transfer within the copolymer. A series of experimental characterizations and density functional theory calculations are applied to elucidate the variation and correlation of the structure and PHE performance of the as‐prepared catalysts. It is found that the best average PHE rate of 3012.5 μmol g−1 h−1 can be achieved over the optimal D‐A copolymer under visible‐light (400 < λ < 800 nm) irradiation, which is ~3.3 times that of pure urea‐derived g‐C3N4. The corresponding apparent quantum efficiency is 1.3% at 420 nm. This study provides a protocol for designing effective visible‐light photocatalysts via D‐A modulation of polymeric semiconductors.

Solar‐driven synthesis of hydrogen peroxide (H2O2) from water and air provides a low‐cost and eco‐friendly alternative route to the traditional anthraquinone method. Herein, four thiazole‐based conjugated polymers (Tz‐CPs: TTz, BTz, TBTz and BBTz) are synthesized via aldimine condensation. BBTz exhibits the highest H2O2 production rate of 7274 μmol g‐1 h‐1 in pure water. Further, the reaction path is analyzed by electron paramagnetic resonance (EPR), in‐situ diffuse reflectance infrared fourier transform (DRIFT) and theoretical calculation, highlighting the prominent role of singlet oxygen (1O2). The generation of 1O2 occurs through the oxidation of superoxide radical (•O2‐) and subsequent conversion into endoperoxides via [4+2] cycloaddition over BBTz, which promotes charge separation and reduces the barrier for H2O2 production. This work provides new insight into the mechanism of photocatalytic O2 reduction and the molecular design of superior single‐polymer photocatalysts.

No abstract

charge carriers, such as morphological control, [10][11][12] elemental doping, [13,14] molecular engineering, [15,16] and heterostructure construction. [17][18][19] In particular, molecular engineering is a rather effective method to regulate the chemical composition and electronic structure of CN.Efforts have been devoted to building organic conjugated copolymers with donor-acceptor system to improve the charge mobility in organic photovoltaic field. [20,21] As such, it is supposed that the construction of intramolecular D-A conjugated copolymers could be a helpful strategy to increase the photocatalytic performance of polymeric photocatalysts. Generally, the D-A conjugated copolymers could be synthesized through the copolymerization between electron donor and acceptor units. The introduction of donor or acceptor units could extend π-conjugated system and induce the intramolecular charge transfer of D-A conjugated copolymers under internal electric field, which help to facilitate the dissociation of photogenerated electrons and holes. [22][23][24][25] Moreover, the construction of D-A structure could flexibly regulate the band structure of conjugated copolymers through the pushpull effect on the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), [22,26,27] narrowing the bandgap of copolymers toward extended visiblelight absorption. For instance, Fan et al. fabricated a range of aromatics-incorporation g-C 3 N 4 -based D-A copolymer via nucleophilic substitution reactions and proposed the concept of intramolecular charge transfer transition to clarify the photo catalytic mechanism upon long-wavelength-light illumination. [24] Creatinine-derived moiety as donor unit was also incorporated into melem by copolymerization of creatinine and urea to broaden the absorption range and promote the charge spatial separation. [28] Chen et al. integrated π-deficient pyridine group with carbon nitride skeleton to modulate the electron structure, enabling tunable bandgap and boosted carrier migration. [29] Herein, modified CN-based conjugated copolymers with D-A structure were obtained by thermal copolymerization of 2-aminobenzimidazole (abIM) and urea (Figure 1a). [30,31] abIM was chosen as the reactant and serves as electron acceptor unit due to its high electron affinity. As expected, the as-prepared D-A polymeric photocatalysts with adjustable bandgap exhibit larger surface area, stronger visible-light absorption and faster charge carrier separation as compared to pristine CN. The photocatalytic hydrogen evolution rate of the optimal sample is 2566 µmol g −1 h −1 , which is ≈2.7 times that of pristine CN.The construction of conjugated copolymers with a donor-acceptor (D-A) system has emerged as a promising strategy for improving photocatalytic activity. Herein, a donor-acceptor modified carbon nitride (CN) conjugated copolymer is fabricated via facile thermal copolymerization of 2-aminobenzimidazole (abIM) and urea. The experimental results demonstrate that the abIM units are successful...