Superior Photocatalytic Performance Research Articles

Sol-Gel technique, characterization and photocatalytic degradation activity of Manganese doped ZnO nanoparticles

Photocatalysis using semiconductor metal oxide stands out as a highly effective and efficient method for eliminating organic pollutants from wastewater. This study aims to assess the photocatalytic capabilities of Mn doped ZnO nanocomposites in degrading methylene blue (MB) dye under ultra-violet light exposure. This study details the synthesis of ZnO photocatalysts through a straightforward one-step sol-gel method, incorporating varying levels of Mn-doping (0%, 2% & 4%). The structural and optical attributes were examined using techniques such as powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and UV-Vis diffuse reflectance spectra. X-ray diffraction analyses verified the presence of a hexagonal wurtzite crystal structure in all synthesized samples, exhibiting a high degree of crystallinity. In addition, an investigation into the impact of Mn impurities on the photocatalytic performance of ZnO catalysts was conducted in the context of methylene blue (MB) degradation. The experimental findings revealed that the Mn doped ZnO nanoparticles produced exhibited significantly superior photocatalytic performance compared to pure ZnO when used in breaking down methylene blue under UV-light exposure. This study proposes that these Mn doped ZnO could serve as a highly effective photocatalyst for treating water contaminated with certain chemically persistent synthetic organic dyes. The improved photocatalytic capabilities of ZnO nanostructures doped with Mn were ascribed to the synergistic impact of increased surface area in ZnO nanosphere and enhanced efficiency in charge separation resulting from optimized Mn doping. A potential explanation for the heightened photocatalytic performance of Mn-doped ZnO nanostructures is proposed tentatively.

Tuning interfacial oxygen vacancy level of bismuth oxybromide to enhance photocatalytic degradation of bisphenol A

Oxygen vacancies (OVs) have garnered significant interest for their role as active sites, enhancing the catalytic efficiency of various catalysts. Despite their widespread application in environmental purification processes, the generation of OVs conventionally depends on high-temperature conditions and strong reducing agents for the extraction of surface partial oxygen atoms from catalysts. In this work, bismuth oxybromide (BiOBr) nanosheets with varying levels of OVs were synthesized via a simple and effective solvothermal method. This novel method affords precise control over the conduction band (CB) and valence band (VB) positions of BiOBr. The presence of different OVs exhibited varying photocatalytic efficiencies in the degradation of bisphenol A (BPA) under visible light irradiation, with higher levels of OVs resulting in superior photocatalytic performance. Furthermore, radical scavenger experiments demonstrated that superoxide oxides (O2•−) and holes (h+) were the primary reactive oxygen species for BPA degradation. Additionally, BiOBr-OVs exhibited excellent anti-interference and stability in water matrices containing diverse inorganic anions and organic compounds. This work provides a simple and effective approach for the fine-regulating of catalysts through interfacial defect engineering, paving the way for their practical application in environmental decontamination.

Efficient visible light-based photocatalytic performance for tetracycline degradation by novel dual z-type ZnO nanorods /Bi2MoO6 /ZIF-67 heterostructure: Mechanism and water matrix investigation

BackgroundContamination of water with antibiotics poses environmental challenges. Photocatalytic semiconductor heterostructure technologies prove effective in water purification, particularly in eliminating pharmaceutical pollutants. Achieving high-quality heterostructures remains a considerable challenge. MethodsZnO/Bi2MoO6/ZIF-67 photocatalyst was synthesized using the ambient temperature method and characterized through XRD, FTIR, SEM, EDX, TEM, UV–vis DRS, TGA, PL, and BET analyses.Significant findings: The novel ZnO/Bi2MoO6/ZIF-67 photocatalyst's efficacy in degrading tetracycline under visible light was evaluated. The optimal composite molar ratio of ZnO: Bi2MoO6: ZIF-67 was found to be 1.53:1:0.4, exhibiting superior photocatalytic performance compared to ZnO, Bi2MoO6, and ZIF-67. With ZnO/Bi2MoO6/ZIF-67, the highest removal efficiency of tetracycline reached 90.3 % under ideal conditions (catalyst dose = 0.4 g/L, pH = 6.5, illumination time = 90 min, initial tetracycline concentration = 40 mg/L). The photocatalytic degradation of tetracycline follows first-order kinetics. The trapping experiments showed that OH• and •O2– species played a beneficial role in enhancing the photodegradation process.

Construction of a direct Z-scheme Cs3Bi2Cl9/g-C3N4 heterojunction composite for efficient photocatalytic degradation of various pollutants in water: Performance, kinetics and degradation mechanism

The use of emerging composite materials has been booming to remove environmental pollutants. The aim of this research is to develop a new composite based on Cs3Bi2Cl9 perovskite and graphitic carbon nitride (g-C3N4) to investigate the photocatalytic performance under visible light irradiation. To achieve this, we produce the Cs3Bi2Cl9/g-C3N4 heterojunctions through a simple self-assembly synthesis. The as-synthesized composites are characterized using XRD, FTIR, FESEM, TEM, BET and EDX techniques. The photocatalytic performance of Cs3Bi2Cl9/g-C3N4 is examined in the degradation of various water contaminants, including 4-nitrophenol (4-NP), tetracycline antibiotic (TC), methylene blue (MB) and methyl orange (MO). The experimental results indicate the superior photocatalytic performance of the composites in the degradation of pollutants compared to pure Cs3Bi2Cl9 and g-C3N4. The 10% Cs3Bi2Cl9/g-C3N4 composite achieves the optimal degradation efficiency of 100, 92, 98.7, and 85.1% of 4-NP, TC, MB, and MO, respectively. This superior photocatalytic activity attributes to improved optical and electrochemical properties, including enhanced absorption ability, narrowing band gap, promoted separation efficiency of photogenerated carriers, and a high redox potential, which is confirmed by UV–vis DRS, PL, EIS, and CV analyses. The 10% Cs3Bi2Cl9/g-C3N4 composite also demonstrates high photocatalytic stability after four consecutive cycles. Radical trapping tests show that superoxide radicals (•O2−), holes (h+), and hydroxyl radicals (•OH) contribute to the photocatalytic process. Based on the obtained data, a direct Z-scheme heterojunction mechanism is proposed. Overall, this research offers a new stable photocatalyst with excellent prospect for photocatalytic applications.

Enhancing photocatalytic degradation of crystal violet dye with g‐C3N4/ZnTiO3 nanocomposites synthesized via a facile approach

AbstractPhotocatalysts that exhibit exceptional performance could be further enhanced for wastewater treatment, particularly in the degradation of organic pollutants and reduction of inorganic heavy metal ions concentrations. This study employed sol–gel techniques was used to create a Type II scheme g‐C3N4/ZnTiO3 (CZT‐2, CZT‐4, and CZT‐6) photocatalyst. FT‐IR, UV‐DRS, XRD, SEM, BET, HR‐TEM, and XPS analysis were conducted to investigate the physical and chemical properties of the g‐C3N4/ZnTiO3 photocatalyst's. An investigation was conducted to evaluate the photocatalytic performance of the synthesized samples. The samples exhibit remarkable efficacy in the degradation of organic contaminants. Among them, CZT‐2 showcased superior photocatalytic performance in the solar light‐induced photodegradation of crystal violet. The photocatalytic activity of g‐C3N4/ZnTiO3 has been significantly enhanced through the establishment of a Type‐II scheme at the interface. This innovative approach efficiently facilitates the separation of photogenerated electron–hole pairs, thereby boosting the photodegradation activity. The discussion also included the chemical process between photocatalysts and crystal violet. The mechanism of the crystal violet‐photocatalyst reaction was also discussed. After undergoing five cycles of reuse, the photocatalyst that was manufactured demonstrated remarkable stability, leading to a reduction in the cost associated with wastewater treatment. The as‐synthesized g‐C3N4/ZnTiO3 composites are very safe for the environment, which suggests that the CZT‐2 composite is very good at getting rid of pollutants.

S-scheme g-C3N4/Ce2S3 nanocomposites for visible-light activation of persulfate ions: Photocatalytic degradations of antibiotics and dyes

An S-scheme g-C3N4/Ce2S3 photocatalyst (abbreviated as CN/Ce2S3) was constructed through a facile hydrothermal method, and used to activate persulfate ions (PS). The CN/Ce2S3 (20 %) nanocomposite exhibited superior photocatalytic performance in removing three antibiotics, including tetracycline (TC), amoxicillin (AMX), azithromycin (AZT), and three dye contaminants, containing methyl orange (MO), methylene blue (MB), and rhodamine B (RhB) upon visible light. The XPS, EDX, XRD, and HRTEM analyses indicated the successful combination of CN and Ce2S3 semiconductors. The photoactivity of CN/Ce2S3 (20 %)/PS system for removing TC was about 51.0, 26.6, and 1.96-fold premier than the PS, CN/PS, and CN/Ce2S3 (20 %) samples, respectively. Besides, the recycled photocatalyst demonstrated remarkable activity even after four recycling applications. The surprising performance of the CN/Ce2S3 (20 %)/PS system was related to the impressive surface area, extended light absorption, and facile charges separation/transfer. Finally, the biocompatibility of the contaminated solution after the photocatalytic reaction was affirmed through the growth of wheat seeds. Accordingly, the S-scheme CN/Ce2S3 photocatalyst can be considered a promising material for the detoxification of the environment.

Enhanced solar light-induced performance of a step-scheme heterojunction nanostructure (C3N4/ZrO2) for mixed dye degradation and methanol oxidation

This study focuses on the high demand for innovative nanostructured materials with boosted photocatalytic performance for the degradation of organic pollutants and oxidation of organic compounds. A nanostructure consisting of graphitic carbon nitride (C3N4) and zirconium oxide (ZrO2) denoted as C3N4/ZrO was synthesized via direct thermal pyrolysis. A comprehensive array of characterization techniques (XRD, FESEM, HRTEM and UV-DRs analysis) was utilized for a detailed analysis of the prepared photocatalysts. The photoactivity of the C3N4/ZrO nanostructure was explored by the photocatalytic degradation of a mixture of dyes (Rh B + CV), and methanol oxidation reaction and compared with those of pristine C3N4 and ZrO2. The photoactivity of C3N4/ZrO for degrading the mixed dye under simulated solar light was 97% higher than those of pristine C3N4 (88%) and ZrO2 (31%). The C3N4/ZrO nanostructure, functioning as a step-scheme heterojunction, demonstrated superior photocatalytic performance due to enhanced charge transport facilitated by robust interfacial contact between C3N4 and ZrO2. This enhanced photodegradation efficiency, reaching 97%, establishes a foundation for the development of heterojunction catalysts with exceptional photocatalytic activities. Furthermore, the methanol oxidation activity of the C3N4/ZrO nanostructure was exceptionally high, yielding a 138.25 mA/cm2 current density at a 2 M methanol. The proposed material has a high application potential for mitigating pollution and energy issues.

Titanium dioxide–supported mercury photocatalysts for oxidative removal of hydrogen sulfide from the air using a portable air purification unit

Photocatalytic removal of gaseous hydrogen sulfide (H2S) has been studied through the control of key process variables using a prototype air purifier (AP) fabricated with titanium dioxide (TiO2)-supported mercury. The performance of Hg/TiO2 systems, prepared with different Hg mass proportions over TiO2 (such as 0.1%, 1%, 2%, and 5%), is measured against 5 ppm H2S at 160 L min-1 under UV irradiation. Accordingly, their removal efficiency (RE) values after 360 s are 40.3%, 74.8%, 99.3%, and 99.9%, respectively (relative to 33.5% of AP (TiO2)). An AP with a 2% Hg/TiO2 unit achieves a clean air delivery rate of 32 L min-1 with kinetic reaction rate (r (at 10% RE)) of 0.774 mmol h-1 g-1, quantum yield of 2.19E-02 molecules photon-1, and space-time yield of 1.46E-04 molecules photon-1 mg-1. The superior photocatalytic performance of Hg/TiO2 is supported by superoxide anion and hydroxyl radicals formed in dry air and humid nitrogen (N2) environments, respectively. A density functional theory simulation suggests that the presence of oxygen vacancies should promote the disparities in the electronic structure to subsequently affect the reaction pathways and energetics. The presence of moisture enhances the robust formation of a mercury-OH bond to favorably yield β-mercury sulfide from H2S.

Defect engineering of Cu2-xGaxO/PDINH nanomaterial for significantly improved photocatalytic antibacterial activities

The judicious engineering of defects and microstructure in novel photocatalysts is essential for optimizing their functional properties. This study focuses on the design of copper oxide (Cu2O)-based catalysts employing defect engineering and heterogeneous composition with perylene-3,4,9,10-tetracarboximide (PDINH) to enhance their photocatalytic antibacterial performance. Introducing transition metals such as gallium (Ga) into the Cu2O lattice serves to 1) generate Cu vacancies to accelerate reactive oxygen species (ROS) kinetics, 2) induce a small size effect in Cu2O nanoparticles to amplify photocatalytic activities, and 3) fine-tune electronic characteristics by modulating the electron density near the Fermi level and the d-band center. The defect engineering of doped Ga atoms and the p-n junction construction with PDINH resulted in a notable redshift of the light absorption edge of Cu2O. The optimized Cu2-xGaxO/PDINH (x=0.2) nanomaterials displayed superior photocatalytic antibacterial performance, achieving bacterial inhibition rates greater than 91% against Staphylococcus aureus and Pseudomonas aeruginosa. The nanomaterial also exhibited a large double-layer capacitance, elevated photocurrent density, and substantial ROS production. Cu1.8Ga0.2O/PDINH nanomaterial was a potent candidate for photocatalysis and environmentally friendly antibacterial treatments.

Enhanced Fenton-like catalysis through in-situ bismuth defection in Bi/CuBi2O4: Vacancy mechanisms

Alleviating the concentration of hazardous bacteria by photocatalysts is an efficient way for treating ballast water. In this work, we present the synthesis of in-situ Bi vacancies on Bi/CuBi2O4, which is assisted by H2O2 for Fenton-like photocatalytic potential in deactivating marine microorganisms in natural seawater (Yellow Sea, China), the optimal Bi vacancy content (3BCBO) is determined and exhibits superior photocatalytic inactivation performance, additional H2O2 activation enhances the production of •OH for comprehensive oxidation, with •OH confirmed as the dominant reactive species. Density functional theory (DFT) calculations highlight the synergistic of vacancies and metallic Bi play a pivotal role in decreasing the energy barrier of H2O2 adsorption for •OH improving production, promotes efficient separation of charge carriers and utilization of visible light, the co-effect of metallic Bi nanoparticles and bismuth defection mechanisms effectively inhibit the madness thriving of marine microorganisms, this work offers an ideal and promising perspective for ballast water treatment on ships.

Cu, B co-modification boosted the photogenerated carrier separation efficiency in C3N4 for enhanced hydrogen evolution

In this work, g-C3N4 (U1W1–CNS) were prepared by calcination and Cu, B co-modified U1W1–CNS (Cu, B–CNS) was successfully fabricated by cryo-ultrasonic loading. B doping formed the unfavourable sub-centers and the Cu loading forms the electron-rich centre, which enhances the built-in electric field on the surface of U1W1–CNS. Hence, the 0.03Cu, 0.05B–CNS record a superior photocatalytic performance the hydrogen production rate reached to 1067 umolg−1h−1, which was 152, 10 and 1.67 times higher than that of U1W1–CNS (7 μmolg−1h−1), BCN (104 μmolg−1h−1) and 0.03Cu–CNS (638 μmolg−1h−1), respectively. This research provides new ideas for the design of U1W1–CNS photocatalyst with high performance photocatalytic hydrogen evolution.

Enhancing photocatalytic efficiency and durability: Ag-modified CNS–TiO2 thin films for sustainable industrial wastewater treatment

This study explores a novel approach to address the persistent challenges encountered in recovering powder catalysts and achieving superior photocatalytic performance tailored for environmental remediation and industrial wastewater (IE) treatment. Isopropyl alcohol (IPA), chosen as the solvent through Liyanage classical equations and zeta potential measurements (−33.6 mV), sets the stage for investigating the critical role of the surfactant (PVP) and binder (SiO2) in optimizing colloidal stability, thin-film coating, and photocatalytic activity. Meticulous experimentation reveals a synergistic 10:1 g/L ratio of PVP and SiO2 solutions as the key to achieving a delicate balance in enhancing colloidal stability, facilitating thin-film coating, and optimizing photocatalytic kinetics (84 ± 3%, k = 0.0303 ± 0.002 min−1). Additionally, the study emphasizes the need for a holistic optimization approach, highlighting colloidal stability and film adhesion to unlock the full potential of these advanced photocatalytic materials in engineering applications.

Superior photocatalytic performance of ZnMoO4/Ag2WO4 for degradation of trimethoprim and methylene blue

ABSTRACT In the present work, ZnMoO4/Ag2WO4 nanocomposite was synthesized via facile hydrothermal and chemical precipitation method for determination of photocatalytic performance on organic contaminants such as methylene blue and trimethoprim. The synthesized nano-photocatalyst was characterized using various instrumental techniques. Photocatalytic degradation of methylene blue and trimethoprim by the samples was realized under UV light irradiation. The obtained results demonstrated that photocatalytic degradation of methylene blue by ZnMoO4/Ag2WO4 was 99.6% in 30 min. The bare ZnMoO4 produced 57.8% and Ag2WO4 produced 76.7% photocatalytic degradation of methylene blue in 60 min. The synthesized ZnMoO4/Ag2WO4 nanocomposite, about which there is little information on remediation of organic pollutants, had possessed the outstanding photocatalytic degradation performance on methylene blue and trimethoprim due to pseudo first order kinetic.

Synthesis of carboxylated cellulose nanocrystal/ZnO nanohybrids using Oxytenanthera abyssinica cellulose and zinc nitrate hexahydrate for radical scavenging, photocatalytic, and antibacterial activities

The extremely low antioxidant, photocatalytic, and antibacterial properties of cellulose limit its application in the biomedical and environmental sectors. To improve these properties, nanohybrides were prepared by mixing carboxylated cellulose nanocrystals (CCNCs) and zinc nitrate hexahydrate. Data from FTIR, XRD, DLS, and SEM spectra showed that, ZnO nanoparticles, with a size ranging from 94 to 351 nm and the smallest nanoparticle size of 164.18 nm, were loaded onto CCNCs. CCNCs/ZnO1 nanohybrids demonstrated superior antibacterial, photocatalytic, and antioxidant performance. More considerable antibacterial activity was shown with a zone of inhibition ranging from 26.00 ± 1.00 to 40.33 ± 2.08 mm and from 31.66 ± 3.51 to 41.33 ± 1.15 mm against Gram-positive and Gram-negative bacteria, respectively. Regarding photodegradation properties, the maximum value (~91.52 %) of photocatalytic methylene blue degradation was observed after 75 min exposure to a UV lamp. At a concentration of 125.00 μm/mL of the CCNC/ZnO1 nanohybrids sample, 53.15 ± 1.03 % DPPH scavenging activity was obtained with an IC50 value of 117.66 μm/mL. A facile, cost-effective, one-step synthesis technique was applied to fabricate CCNCs/ZnO nanohybrids at mild temperature using Oxytenanthera abyssinica carboxylated cellulose nanocrystals as biotemplate. The result showed that CCNCs/ZnO nanohybrids possess potential applications in developing advanced functional materials for dye removal and antibacterial and antioxidant applications.

Construction of intramolecular and interfacial built-in electric field in a donor-acceptor conjugated polymers-based S-scheme heterojunction for high photocatalytic H2 generation

Engineering a robust built-in electric field (IEF) is favorable for boosting carrier separation and achieving high photocatalytic performance. Herein, we developed a donor-acceptor conjugated polymer-based S-scheme heterojunction, utilizing both intramolecular and interfacial IEF to enhance carrier separation and achieve superior photocatalytic performance. Specifically, the intramolecular IEF was established by introducing 1,6-dibromopyrene into carbon nitride (CN) to form 1,6-dibromopyrene grafted CN (CNPy). Concurrently, the S-scheme heterojunction was formed by coupling CNPy with CdSe nanoparticles to create an interfacial IEF. Experimental findings demonstrated that the combined effect of intramolecular and interfacial IEF within the CdSe/CNPy heterojunction significantly improved the carrier separation and retained strong redox capacity. Benefiting from these advantages, the optimized composite, 100%CdSe/CNPy-0.2, showed the highest H2 generation rate of 1.16 mmol·g−1·h−1, surpassing those of pure CNPy-0.2, CdSe and 100%CdSe/CN by 58, 2.2 and 2.32 times, respectively. This study introduces an innovative design strategy for IEF-regulated conjugated polymer-based materials, paving the way for efficient solar-to-chemical energy conversion.

Silver-decorated SrTiO3 nanoparticles for high-performance supercapacitors and effective remediation of hazardous pollutants.

SrTiO3/Ag nanocomposites were synthesized using a facile wet impregnation method, employing rigorous experimental techniques for comprehensive characterization. XRD, FTIR, UV, PL, FESEM, and HRTEM were meticulously utilized to elucidate their structural, functional, morphological, and optical properties. The electrochemical performance of the SrTiO3/Ag nanocomposite was rigorously assessed, revealing an impressive specific capacitance of 850 F/g at a current density of 1A. Furthermore, the photocatalytic activity of the SrTiO3/Ag nanocomposite was rigorously examined using methylene blue (MB) dye, and the results were outstanding. After 120min of UV irradiation, the nanocomposite exhibited an exceptional MB dye degradation efficiency exceeding 88%. The SrTiO3/Ag nanocomposite represents an exemplary catalyst in terms of efficiency, cost-effectiveness, environmental compatibility, and reusability. The electron and superoxide radicals play a chief role in the MB dye degradation process. The inclusion of Ag within the SrTiO3 matrix facilitated the formation of a conductive nano-network, ultimately resulting in superior capacitive and photocatalytic performance.

Hydrothermal synthesis and photocatalytic application of ZnS-Ag composites based on biomass-derived carbon aerogel for the visible light degradation of methylene blue.

A facile and cost-effective hydrothermal followed by precipitation method is employed to synthesize visible light-driven ZnS-Ag ternary composites supported on carbon aerogel (CA). Extensive studies were conducted on the structural, morphological, and optical properties, confirming the successful formation of ternary nanocomposites. The obtained results evidently demonstrate the successful loading of ZnS and Ag onto the surface of the CA. High-resolution transmission electron microscopy analysis revealed that ZnS and Ag nanoparticles (AgNPs) were uniformly distributed on the surface of the CA with an average diameter of 18nm. The biomass-derived CA, containing a hierarchical porous nano-architecture and an abundant number of -NH2 functional groups on the surface, can greatly prevent the agglomeration, stability and reduce particle size. Brunauer-Emmett-Teller analysis results indicated specific surface areas of 4.62m2g-1 for the CA, 48.50m2g-1 for the CA/ZnS composite, and 62.62m2g-1 for the CA/ZnS-Ag composite. These values demonstrate an increase in surface area upon the incorporation of ZnS and Ag into the CA matrix. Under visible light irradiation, the synthesized CA/ZnS-Ag composites displayed remarkably improved photodegradation efficiency of methylene blue (MB). Among the tested samples, the CA/ZnS-Ag composites exhibited the highest percentage of photodegradation efficiency, surpassing ZnS, CA, and CA/ZnS. The obtained percentages of degradation efficiency for CA, ZnS, CA/ZnS, and CA/ZnS-Ag composites were determined as 26.60%, 52.12%, 68.39%, and 98.64%, respectively. These results highlight the superior photocatalytic performance of the CA/ZnS-Ag composites in the degradation of MB under visible light conditions. The superior efficiency of the CA/ZnS-Ag composite can be attributed to multiple factors, including its elevated specific surface area, inhibition of electron-hole pair recombination, and enhanced photon absorption within the visible light spectrum. The CA/ZnS-Ag composites displayed consistent efficiency over multiple cycles, confirming their stable performance, reusability, and enduring durability, thereby showcasing the robust nature of this composite material.

New breakthrough in rapid degradation of lignin derivative compounds · A novel high stable and reusable green organic photocatalyst

The pulp and paper sectors are thriving yet pose significant environmental threats to water bodies, mainly due to the substantial release of pollutants. Lignin-derived compounds are among the most problematic of these contaminants. To address this issue, we present our initial results on utilizing organic semiconductor photocatalysis under visible light for treating lignin-derived compounds. Our investigation has been centered around creating a green and cost-effective organic semiconductor photocatalyst. This catalyst is designed using a structure of bagasse cellulose spheres to support PM6 (poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophen-2-yl)benzo[1,2-b:4,5-b’]dithiophene))–co-(1,3-di(5-thiophene-2-yl)-5,7-bis(2-ethylhexyl)-benzo[1,2-c:4,5-c’]dithiophene-4,8-dione))]: MeIC (3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-cyclopentane-1,3-dione[c]-1-methyl-thiophe))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d’]-s-indaceno[1,2-b:5,6-b’]-dithiophene)). This photocatalyst demonstrates remarkable efficiency, achieving over 91 % degradation of lignin-derived compounds. The superior photocatalytic performance is attributed to three main factors: (1) The ability of PM6 to broaden MeIC's absorption range from 300 to 800 nm, allowing for effective utilization of visible light; (2) the synergistic interaction between PM6 and MeIC, which ensures compatible energy levels and a vast, evenly spread surface area, promoting charge mobility and extensive donor/acceptor interfaces. This synergy significantly enhances the generation and transport of carriers, resulting in a high production of free radicals that accelerate the decomposition of organic materials; (3) The deployment of PM6:MeIC on biomass-based carriers increases the interaction surface with the organic substances. Notably, PM6: MeIC showcases outstanding durability, with its degradation efficiency remaining between 84 % and 91 % across 100 cycles. This study presents a promising approach for designing advanced photocatalysts aimed at degrading common pollutants in papermaking wastewater.

In-situ decorated cobalt phosphide cocatalyst on Hittorf's phosphorus triggering efficient photocatalytic hydrogen production

Hittorf's phosphorus (HP) is a promising visible-light-driven photocatalyst, yet the slow charge migration and sluggish surface reaction kinetics have limited its photocatalytic hydrogen evolution reaction (HER) efficiency. In this work, cobalt phosphide (CoP2) modified rod-like HP (HP/CoP2) composite was designed and synthesized by a template-assisted chemical vapor deposition strategy. The optimal HP/CoP2 composite yields a HER rate reaching 13.1 μmol·h-1 through pure water splitting under visible light irradiation, which is approximately 4 times higher than that of HP using Pt as cocatalyst (3.3 μmol·h-1). It was experimentally indicated that the accelerated photogenerated charge transfer and promoted surface HER kinetics in the composite gave rise to the superior photocatalytic HER performance.

Perylene diimide covalent organic frameworks super-reductant for visible light-driven reduction of aryl halides

In recent years, there has been a growing interest in the utilization of molecular photocatalysts in their radical ionic forms, especially as visible-light super-reductants. These catalysts exhibit remarkable capabilities in facilitating otherwise inert high-potential organic reactions, such as the reduction of aryl halides to aryl radicals. However, the development of heterogeneous super-reductants has lagged behind due to the deactivation effect caused by molecular aggregation. This study presents a novel approach to address this limitation by heterogenizing perylene diimides (PDIs) super-reductants with a consecutive photo-induced electron transfer mechanism into two-dimensional donor-acceptor (D-A) covalent organic frameworks (COFs). Both COFs, possessing D-A electronic structures and photothermal effects, demonstrated superior visible-light photocatalytic performance compared to their homogeneous counterparts. They achieved up to 99% conversion in the dehalogenation of aryl halides, primarily through a hydrogen atom trapping aryl radical mechanism. Additionally, we conducted a comparative investigation of the excited states of radical anionic D-A-type COFs and DPPDI using femtosecond transient absorption spectroscopy. Notably, the lifetimes of COFs were significantly prolonged, measuring 210 and 260 ps, respectively, compared to the 150 ps lifetime of (DPPDI•−). This study offers valuable insights into the design of efficient free radical ion-type photocatalysts, with potential applications in various chemical transformations.