Visible Light-Driven D-A Conjugated Linear Polymer and Its Coating for Dual Highly Efficient Photocatalytic Degradation and Disinfection

Enhanced photocatalytic performance in seawater of donor-acceptor type conjugated polymers through introduction of alkoxy groups in the side chain

Previous studies have demonstrated that the donor (D)-acceptor (A) structure enables conjugated polymers (CPs) to effectively inhibit charge recombination, reduce exciton binding energy to a minimum, and broaden the light absorption spectrum, ultimately enhancing photocatalytic activity. Besides, side chain engineering is an effective approach to enhance photocatalytic performance by regulating surface chemistry and energy band structure of CPs. Herein, three D-A type CPs, namely TPD-T, TPD-MOT and TPD-DOT, were designed and synthesized using thieno[3,4-c]pyrrole-4,6-dione (TPD) as A units and thiophene with different alkyl/alkoxy groups side chain (as 3-octylthiophene (T), 3-methoxythiophene (MOT) and 3,4-ethylenedioxythiophene (DOT)) as D units, via an atom- and step-economic CH/CH cross-coupling polycondensation. The photocatalytic hydrogen production performance of these polymers driven by visible light was systematically evaluated in pure water and natural seawater. The results show that the hydrogen evolution rates (HERs) of the as-synthesized CPs in pure water and natural seawater significantly increased by 5 and 7 times, respectively, when the number of alkoxy groups on the side chain of polymers increased from 0 to 2. In particular, HERs of three polymers in natural seawater are distinctly better than that in pure water. Further, the steady-state photoluminescence (PL), time-resolved fluorescence decay, and electrochemical impedance spectroscopy (EIS) studies combined with density functional theory (DFT) simulations were carried out to figure out the possible mechanism of the enhanced photocatalytic performance of CPs by side chain engineering. This work indicates that side chain engineering contributes significantly to determine the photocatalytic activity of D-A polymers-based photocatalysts, and could serve as guidelines for organic photocatalysts with highly efficient hydrogen evolution performance.

Study on photocatalytic degradation and antibacterial properties of conjugated microporous polymers/TiO2 composite membranes

Conjugated microporous polymers (CMPs) are widely used in the field of photocatalysis due to their unique conjugated structures and various synthesis methods. Herein, we report the design and synthesis of conjugated microporous polymers hollow spheres (CMPs-HS) superhydrophilic modified by acetylcysteine (CMPs-HS-S) and compounded with the inorganic semiconductor material titanium dioxide (CMPs-HS-S/TiO2) for efficient photocatalytic degradation. To facilitate recycling, the composite membrane material was prepared by combining the materials mentioned above with PVDF membrane. The composite membrane materials had good hydrophilic and photocatalytic properties. Under visible light, the degradation rate of tetracycline (TC) (10 mg/L 180 min) reached 90 %, and the bactericidal rates for Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were 89 % and 99.99 %, respectively. The efficient photocatalytic performance of the composite membranes could be attributed to the hollow sphere structure of CMPs and the role of TiO2 as a photogenic electron transfer platform. Additionally, the hydrophilicity of the membrane also helped to accelerate the occurrence of photocatalytic reactions. After electron paramagnetic resonance (EPR) detection, h+, 1O2 and O2- were proved to be important reactive substances, which played a major role in degradation. These studies reflect the versatility of CMPs-based photocatalysts and provide a new idea for the future development of CMPs-based photocatalysts.

Spin polarization induced by atomic strain of MBene promotes the ·O2- production for groundwater disinfection

Superbugs in groundwater are posing severe health risks through waterborne pathways. An emerging approach for green disinfection lies at photocatalysis, which levers the locally generated superoxide radical (·O2-) for neutralization. However, the spin-forbidden feature of O2 hinders the photocatalytic generation of active ·O2-, and thus greatly limited the disinfection efficiency, especially for real groundwater with a low dissolved oxygen (DO) concentration. Herein, we report a class of strained Mo4/3B2-xTz MBene (MB) with enhanced adsorption/activation of molecular O2 for photocatalytic disinfection, and find the strain induced spin polarization of In2S3/Mo4/3B2-xTz (IS/MB) can facilitate the spin-orbit hybridization of Mo sites and O2 to overcome the spin-forbidden of O2, which results in a 16.59-fold increase in ·O2- photocatalytic production in low DO condition (2.46 mg L-1). In particular, we demonstrate an In2S3/Mo4/3B2-xTz (50 mg)-based continuous-flow-disinfection system stably operates over 62 h and collects 37.2 L bacteria-free groundwater, which represents state-of-the-art photodisinfection materials for groundwater disinfection. Most importantly, the disinfection capacity of the continuous-flow-disinfection system is 25 times higher than that of commercial sodium hypochlorite (NaOCl), suggesting the practical potential for groundwater purification.

Efficient photodegradation of carbamazepine by organocatalysts incorporating a third component with a more complementary absorption spectrum

Carbamazepine, recognized as one of the most prevalent pharmaceuticals, has attracted considerable attention due to its potential impact on ecosystems and human health. In response, this work synthesized and characterized a novel environmentally friendly and cost-effective organic semiconductor photocatalyst PM6:Y6:ITCPTC loaded with coconut shell charcoal, and then investigated its performance for photocatalytic removal. Remarkably, carbamazepine demonstrated a photodegradation efficiency exceeding 99% within a mere 20 minutes of exposure to one sunlight intensity, and also showed good effectiveness under a low light intensity of 50 W. The catalyst exhibited exceptional reusability and stability, maintaining degradation efficiency between 95-99% over 25 cycles. The high photocatalytic activity of PM6:Y6:ITCPTC is primarily attributed to the incorporation of the third component (named ITCPTC), which enhances exciton dissociation and carrier transfer, generating superoxide radicals, electrons, and holes. Furthermore, the plausible degradation pathway of carbamazepine was proposed based on the measured intermediates and density functional theory calculations.

D-A Conjugated Polymer/CdS S-Scheme Heterojunction with Enhanced Interfacial Charge Transfer for Efficient Photocatalytic Hydrogen Generation

Owing to the improved charge separation and maximized redox capability of the system, Step-scheme (S-scheme) heterojunctions have garnered significant research attention for efficient photocatalysis of H2 evolution. In this work, an innovative linear donor-acceptor (D-A) conjugated polymer fluorene-alt-(benzo-thiophene-dione) (PFBTD) is coupled with the CdS nanosheets, forming the organic-inorganic S-scheme heterojunction. The CdS/PFBTD (CP) composite exhibits an impressed hydrogen production rate of 7.62 mmol g-1 h-1 without any co-catalysts, which is ≈14 times higher than pristine CdS. It is revealed that the outstanding photocatalytic performance is attributed to the formation of rapid electron transfer channels through the interfacial Cd─O bonding as evidenced by the density functional theory (DFT) calculations and in situ X-ray photoelectron spectroscopy (XPS) analysis. The charge transfer mechanism involved in S-scheme heterojunctions is further investigated through the photo-irradiated Kelvin probe force microscopy (KPFM) analysis. This work provides a new point of view on the mechanism of interfacial charge transfer and points out the direction of designing superior organic-inorganic S-scheme heterojunction photocatalysts.

Enhanced Photocatalytic Properties of All-Organic IDT-COOH/O-CN S-Scheme Heterojunctions Through π-π Interaction and Internal Electric Field

Herein, we present a distinct methodology for the in situ electrostatic assembly method for synthesizing a conjugated (IDT-COOH)/oxygen-doped g-C3N4 (O-CN) S-scheme heterojunction. The electron delocalization effect due to π-π interactions between O-CN and self-assembled IDT-COOH favors interfacial charge separation. The self-assembled IDT-COOH/O-CN exhibits a broadened visible absorption to generate more charge carriers. The internal electric field between the IDT-COOH and the O-CN interface provides a directional charge-transfer channel to increase the utilization of photoinduced charge carriers. Moreover, the active species (•O2-, h+, and 1O2) produced by IDT-COOH/O-CN under visible light play important roles in photocatalytic disinfection. The optimum 40% IDT-COOH/O-CN can kill 7-log of methicillin-resistant Staphylococcus aureus (MRSA) cells in 2 h and remove 88% tetracycline (TC) in 5 h, while O-CN only inactivates 1-log of MRSA cells and degrades 40% TC. This work contributes to a promising method to fabricate all-organic g-C3N4-based S-scheme heterojunction photocatalysts with a wide range of optical responses and enhanced exciton dissociation.

Polymerization-Enhanced Photophysical Performances of AIEgens for Chemo/Bio-Sensing and Therapy

AIE polymers have been extensively researched in the fields of OLEDs, sensing, and cancer treatment since its first report in 2003, which have achieved numerous breakthroughs during the years. In comparison with small molecules, it can simultaneously combine the unique advantages of AIE materials and the polymer itself, to further enhance their corresponding photophysical performances. In this review, we enumerate and discuss the common construction strategies of AIE-active polymers and summarize the progress of research on polymerization enhancing luminescence, photosensitization, and room-temperature phosphorescence (RTP) with their related applications in chemo/bio-sensing and therapy. To conclude, we also discuss current challenges and prospects of the field for future development.