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The development of durable and highly efficient visible-light-driven photocatalysts is essential for the photo- catalytic ozonation process towards degrading organic pollutants. This study presents CN-MA, a novel photo- catalyst synthesized by grafting carbon nitride (CN) with single-atom Mn and 2-hydroxy-4,6-dimethylpyrimidine (HDMP) via one-step thermal polymerization. Experimental characterization and theoretical calculation results reveal that incorporating single-atom Mn and HDMP into CN alters the charge density distribution on the heptazine rings. This modification enhances the absorption of visible light and reduces exciton binding energy, leading to improved separation and migration of photogenerated charge carriers. Moreover, the single-atom Mn provides abundant active sites for O3 adsorption and activation, which increases the utilization of photo- generated electrons to produce highly reactive oxidative species. Consequently, CN-MA exhibits superior photocatalytic ozonation activity, achieving 94% mineralization of phenol within 60 min and maintaining excellent stability over multiple cycles. The research also proposes a plausible reaction mechanism based on free-radical trapping experiments and steady-state concentration experiments using molecular probes. This strategy advances the development of molecular-engineered catalysts co-modified with single metal atoms, thereby enhancing the photocatalytic ozonation process for the degradation of organic pollutants.

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Carbon nitride Molecular engineering Photocatalytic ozonation Single-atom

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Presented herein are the delicate design and synthesis of S-scheme NiTiO3 /CdS heterostructures composed of CdS nanoparticles anchored on the surface of NiTiO3 nanorods for photocatalytic CO2 reduction. Systematic physicochemical studies demonstrate that NiTiO3 /CdS hybrid empowers superior light absorption and enhanced CO2 capture and activation. Electron spin resonance validates that the charge carriers in NiTiO3 /CdS follow a S-scheme transfer pathway, which powerfully impedes their recombination and promotes their separation. Importantly, the photogenerated holes on CdS are effectively consumed at the hero-interface by the electron from NiTiO3 , preventing the photo-corrosion of the metal sulfide. As a result, with Co(bpy)3 2 + as a cocatalyst, NiTiO3 /CdS displays a considerable performance for CO2 reduction, affording a high CO yield rate of 20.8 mu mol h-1 . Moreover, the photocatalyst also manifests substantial stability and good reusability for repeated CO2 reaction cycles in the created tandem photochemical system. In addition, the possible CO2 photoreduction mechanism is constructed on the basis of the intermediates monitored by in-situ diffuse reflectance infrared Fourier transform spectroscopy. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

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CO 2 reduction Heterojunction NiTiO3 Photocatalysis S-scheme

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Covalent organic frameworks (COFs) containing dioxin-linkages are highly valued for their exceptional chemical stability, which is essential for practical use. However, research on dioxin-based COFs remains limited. Herein, a unique nonplanar 2D COF, designated as TCP-COF, constructed from catechol-porphyrin units interconnected by 1,4-dioxin bonds, exhibiting a staggered AAA stacking pattern, is presented. Remarkably, TCP-COF can undergo in situ exfoliation to produce ultrathin 2D nanosheets when it is utilized as a photocatalyst for hydrogen peroxide (H2O2) generation in water and air, without the need for additives. This exfoliation process is primarily driven by the distortion of porphyrin units and weak pi-pi interaction between adjacent layers in TCP-COF. The resultant ultrathin nanosheets significantly reinforce catalytic activity, achieving a photocatalytic H2O2 production rate of 3077 mu mol g(-1) h(-1). The mechanism underlying H2O2 photosynthesis is further explored through a combination of experimental analyses and theoretical calculations. This study provides valuable insights for the development of efficient COF-based photocatalysts for H2O2 evolution.

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catechol-porphyrin covalent organic frameworks dioxin linkage H2O2 photosysnthesis photochemical exfoliation

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Sulfur mustard, a highly toxic chemical warfare agent, poses a significant threat to human health. Consequently, the development of efficient and rapid decontamination strategies is of paramount importance. However, current degradation methods are often hindered by slow reaction rates and limited selectivity. Herein, we report a facile one-pot in situ self-assembly method to simultaneously modify the photosensitizer rose bengal (RB) into both the cavities and surface of zeolitic imidazolate framework-8 (ZIF-8), resulting in the formation of the RB@ZIF-8 composite. The RB@ZIF-8 composite demonstrates exceptional singlet oxygen (1O2) photosensitization capacity, serving as a visible-light-driven heterogeneous photocatalyst that enables selective oxidation of a sulfur mustard simulant (2-chloroethyl ethyl sulfide, CEES) to the corresponding non-toxicity sulfoxide derivative. This system achieves complete conversion within 6 minutes, with a reaction half-life of 2.5 minutes under ambient conditions. Moreover, the composite demonstrates outstanding recyclability and reusability. This work provides a promising strategy for the design of advanced MOF-based heterogeneous photosensitizers, offering a highly efficient, selective, and reusable platform for the rapid detoxification of sulfur mustard under mild conditions.

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The precise regulation of photocatalytic oxygen reduction reaction (ORR) pathways, particularly the more energy-efficient one-step 2e(-) route, is of fundamental importance for optimizing H2O2 production efficiency in rationally designed covalent organic frameworks (COFs). Here, a strengthened donor-acceptor (D-A) structured TPCN-COF [COF synthesized from 2,4,6-hydroxy-1,3,5-benzotricarboxaldehyde and 1,3,5-tris (4-aminophenyl) benzene] photocatalyst was developed through the strategic incorporation of pyridine nitrogen moieties into the COF skeleton. The strengthened D-A structure facilitates effective separation of photogenerated charge carriers while promoting rapid electron transfer kinetics. Concurrently, the introduced pyridine nitrogen units increase the surface polarity, thereby improving hydrophilicity and enabling more efficient proton delivery to active sites. Remarkably, the synergistic combination of enhanced charge separation and optimized proton transport in TPCN-COF effectively shifts the ORR mechanism from two-step 1e(-) pathway to one-step 2e(-) process. As a result, TPCN-COF achieves an exceptional H2O2 production rate of 1320.9 mu molg(-1)h(-1) under visible light irradiation (lambda >= 420 nm) in an air-equilibrated aqueous system, representing a nearly 3-fold enhancement compared to the unmodified TPCC-COF [COF synthesized from 2,4,6-hydroxy-1,3,5-benzotricarboxaldehyde and 5,5 ',5 ''- (benzene-1,3,5-triyl) tris (pyridin-2-ylamino)]. This work establishes an effective design strategy for constructing COFs photocatalysts with strong D-A structures, and elucidates the synergistic regulatory mechanism, by which both electronic structure and surface properties govern ORR pathway selectivity in COF-based systems.

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Covalent organic framework (COF) D-A structure H2O2 preparation Photocatalysis Reaction pathway

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Designing efficient photocatalysts for photocatalysis hydrogen production is crucial for advancing green energy technologies. In this work, ZnIn2S4 photocatalyst with an asymmetric Zn-Zn-S unit ring structure and abundant in S vacancies was achieved by precisely tuning the molar mass of the Zn ion source using ethylene glycol as the reaction solvent. Z-type heterojunction was constructed via the electrostatic assembly by combining silver clusters (Agx@GSH) with ZnIn2S4 to enhance charge separation and photocatalytic activity. The structural transition from S-Zn-S to Zn-Zn-S led to local charge redistribution. Meanwhile, S vacancies acted as electron traps, promoting the charge state change of S in the S-H sites and significantly accelerates the hydrogen evolution reaction (HER). The composite catalyst Zn-Vs-ZIS/Agx@GSH exhibited a hydrogen production rate of 18.4 mmol & sdot;g-1 & sdot;h-1, under acidic conditions with lactic acid as the sacrificial agent, which is 3.7 times higher than pristine ZnIn2S4. Density functional theory (DFT) calculations revealed that the Zn-Zn-S distortion and heterojunction formation synergistically enhanced charge transfer and hydrogen adsorption kinetics. This work provides a novel approach for tailoring ZnIn2S4-based photocatalysts and provides new insights into the design of high-performance heterojunction systems for solar energy conversion.

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Heterojunction Indium zinc sulfide Local charge redistribution Photocatalytic hydrogen production Silver nanoclusters

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Photosynthesis of H2O2 from O-2 and H2O with inexhaustible sunlight as an energy source is a promising approach. However, the photocatalytic performance of pristine polymeric carbon nitride (PCN) is extremely restrained due to the rapid recombination of photo-generated electrons and holes, and slow surface reaction processes. Herein, a new strategy is developed to rationally integrate N, S-co-doped carbon (C-NS), and CoS2 on cyano-rich PCN (PCN-Cy) for photosynthesis of H2O2 under ambient conditions. The engineering with cyano groups (electron-withdrawing groups) promotes the bulk charge separation of PCN. Experimental results reveal that the CoS2 co-catalyst not only serves as an electron acceptor to extract charges from the bulk but also functions as an active site to promote the 2-e(-) ORR process. Besides, the N, S-co-doped carbon performs as an electron channel to promote migration of charges at the interface of PCN-Cy and CoS2. Accordingly, the as-synthesized cyano-rich PCN photocatalyst integrated with N, S-co-doped carbon and CoS2 exhibits a remarkable activity of 321.9 mu m h(-1) for photocatalytic production of H2O2, which is 44.9 times higher than that of the pristine PCN.

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2-electron oxygen reduction reaction charge transfer H2O2 production overall photosynthesis polymeric carbon nitride

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The urgent need to address the high prevalence of waterborne diseases in underdeveloped regions necessitates the development of economically viable, decentralized, and sunlight-assisted disinfection techniques. An encouraging solution lies in the utilization of photosynthesized H2O2 to initiate advanced oxidation processes (AOPs). However, challenges persist in the quest to develop efficient photocatalysts and reactor designs. Herein, we present the rational design and synthesis of a metal-free supramolecular photocatalyst achieved via the postfunctionalization of fluorine-substituted covalent organic frameworks (FCOFs) with polyvinylpyrrolidone (PVP). The resulting FCOF/PVP composite establishes intermolecular C-F center dot center dot center dot C=O interactions at the interface, which facilitate accelerated charge separation and transfer, as well as promote efficient intersystem crossing to enhance the formation of molecular triplet excitons. These photophysical enhancements enable dual-pathway H2O2 generation mediated by superoxide radicals (center dot O2-) and singlet oxygen (1O2), yielding a H2O2 production rate of 1763.50 mu mol/g/h from pure water and atmospheric oxygen. The photosynthesized H2O2 is subsequently catalyzed by Fe(II) to generate hydroxyl radicals (center dot OH), achieving effective inactivation of pathogenic bacteria and viruses. A continuous-flow system was further developed to couple photocatalytic H2O2 production with Fenton disinfection, combining the benefits of heterogeneous and homogeneous catalysis while addressing limitations in photocatalyst recovery and light dependency. This system exhibited robust disinfection performance under real water matrices and intermittent light conditions. Economic analysis supports the feasibility of the system for deployment in resource-limited settings, offering a novel material-based approach for decentralized water treatment and global efforts to mitigate waterborne diseases.

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C-F center dot center dot center dot C=O interaction COF-based photocatalyst Continuous-flow disinfection system Fenton reaction

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Photocatalytic hydroxylation of benzene in water using H2O2 as the oxidant is a green approach toward phenol synthesis. However, the immiscibility of benzene in water results in poor photocatalytic performance and a low efficiency of H2O2 utilization. To enhance drastically the affinity between the aqueous and nonaqueous phases, an amphiphilic heterojunction (Fe2O3/crystalline carbon nitride (CCN)) has been synthesized by intimately immobilizing hematite (Fe2O3) nanoparticles on a CCN surface for the photocatalytic hydroxylation of benzene to phenol. The unique amphiphilicity of Fe2O3/CCN allows the formation and stabilization of homogeneous emulsions in a benzene/water mixture to increase the effective oil/water interface area for more efficient mass transport. Moreover, the well-established type II heterojunction between Fe2O3 and CCN facilitates the fast separation and transfer of photoelectrons from CCN to Fe2O3 for the photo-Fenton activation of H2O2 with high utilization efficiency. We recorded a maximum phenol conversion of 31.6% by using a stoichiometric amount of H2O2 (10 mmol) on the photocatalytic hydroxylation of benzene. The apparent quantum yield of phenol production at lambda = 420 nm was determined to be 47.1%. This amphiphilic photocatalyst approach would be useful for realizing other advanced oxidation reactions involving immiscible components.

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benzene hydroxylationreaction carbon nitride green synthesis phenol synthesis photocatalysis

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A novel dual-function ZnAl–LDH/Bi4O5Br2 nanocomposite photocatalyst was synthesized using a self-assembly process and optimized by response surface methodology for the advanced treatment of wastewater micropollutants. A series of characterizations revealed that ZnAl–LDH/Bi4O5Br2 exhibits suitable heterojunction structure and excellent optoelectronic properties. As a result, ZnAl–LDH/Bi4O5Br2 achieved the near-complete removal of bisphenol A (BPA) after 120 min through a synergistic process of adsorption and visible-light photocatalysis. The corresponding reaction rate constant for photocatalytic degradation approached 0.14 min−1, which is significantly higher than those by Bi4O5Br2 and ZnAl–LDH. Regarding the enhanced BPA removal over ZnAl–LDH/Bi4O5Br2, the adsorption behavior occurred via hydrogen bonding and π-π stacking interactions, while the photocatalytic degradation involved the efficient photoexcitation and separation of charge carriers for the formation of reactive oxygen species (ROS) under the heterojunction effect. Electron spin resonance (ESR) and radical quenching experiments indicated that ROS including ·OH, ·O2−, and 1O2, mainly contribute to BPA degradation. The predominant ROS formation mechanism was the interfacial reactions of the nanocomposite with H2O molecules, as verified by the density of states, charge density differences, and adsorption energy calculations. Furthermore, the intermediate products of BPA degradation were identified, the degradation pathways were proposed, and the related ecotoxicity consequences were evaluated. This study confirmed that ZnAl–LDH/Bi4O5Br2 has superior synergistic adsorptive and photocatalytic performance, offering guidance in the further construction and application of functional nanocomposites for wastewater treatment. © 2025 Elsevier Inc.

Keyword ：

Electron resonance Equilibrium constants Free radical reactions Hydrogen bonds Optical conductivity Photocatalytic activity Photodegradation Rate constants Reaction intermediates

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