Separation Efficiency Of Charge Carriers Research Articles

Modulation of the Microstructure and Enhancement of the Photocatalytic Performance of g-C3N4 by Thermal Exfoliation

This work explores the impact of reaction temperature during thermal exfoliation treatment of bulk-g-C3N4 in the air atmosphere on the structure and performance of the resulting CN photocatalyst. The analysis conducted using XRD, FT-IR, XPS, SEM, and elements mapping tests, illustrated an increase in nitrogen-vacancy and oxygen content on the surface of the CN photocatalyst, resulting in a porous and sparse structure, changes in crystal size, and improved visible light absorption performance. The photocatalytic reduction experiments of hexavalent chromium (Cr(VI)) showed that the CN-540 showed the highest reduction rate of 96.9%, with a reaction rate constant 6.21 times that of bulk-g-C3N4. After 100 min of illumination, the photocatalytic degradation rates of CN-540 for TC-HCl and RhB were 66.7% and 60.6%, respectively. The TOC test results indicated mineralization rates of 51.5% for TC-HCl and 46.6% for RhB. Room temperature fluorescence spectroscopy (PL), transient photocurrent response (TPC), and electrochemical impedance spectroscopy (EIS) measurements confirmed the excellent photogenerated charge carrier separation and transport efficiency of CN-540. The photocatalytic mechanism for reducing Cr(VI) by CN-540 was elucidated based on the active species •OH and •O2– and Mott-Schottky (M-S) tests. This study provides experimental data for optimizing the photocatalytic performance of g-C3N4 and paves a new way for developing efficient photocatalysts. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Tailoring Carrier Dynamics of BiVO4 Photoanode via Dual Incorporation of Au and Co(OH)x Cooperative Modification for Photoelectrochemical Water Splitting

AbstractPhotoelectrochemical solar to hydrogen production is a promising way to achieve carbon neutrality, but severe charge recombination in photoanodes limits the conversion efficiency. Herein, Au nanoparticles and Co(OH)x co‐sensitized bismuth vanadate (BiVO4) to construct AuCo(OH)x/BiVO4 photoanode for significantly enhancing the performance of photoelectrochemical water splitting. This process significantly improves the bulk charge carrier separation efficiency, the surface kinetics of water oxidation, and the electron density of BiVO4 photoanode through Au surface plasmon resonance (SPR) and Co(OH)x oxygen evolution catalysts effect. Additionally, the enhancement of the *O and the *OOH generation accelerate the oxygen evolution reaction kinetics. Consequently, the constructed AuCo(OH)x/BiVO4 photoanode demonstrates an excellent photocurrent of 6.2 mA cm−2 at 1.23 V versus reversible hydrogen electrode and a stable continuous output within 42 h. This work contributes to developing high‐efficiency and high‐stability photoanodes for solar H2 production through SPR effect and oxygen evolution catalysts.

Carbazole and Triazine-Based D-A Covalent Organic Framework for Visible Light-Mediated Photocatalytic C-H Activation of Imidazopyridine and Indole.

Two-dimensional donor-acceptor covalent organic frameworks (COFs) show considerable promise for metal-free and heterogeneous photocatalysis due to their efficient charge carrier separation and exciton transport upon photoexcitation. To date, numerous photocatalysts have been developed. However, they encounter several challenges, such as inadequate sunlight harvesting ability, poor photostability, and nonreusability. Fortunately, the emergence of COFs presents a promising solution to these problems. Herein, we report an imine-linked CzTA-TAPT COF featuring carbazole as the electron donor and triazine as the electron acceptor. Compared to the previously reported C2-linker-derived CzDA-TAPT COF, this C3-linked COF exhibits good charge separation and charge carrier transport. As a consequence, it demonstrates excellent photocatalytic applicability in the C-3 thiocyanation of imidazo[1,2-a]pyridine and indole under ambient conditions under visible light. Moreover, its broad substrate compatibility and high recyclability provide a green and sustainable approach for the thiocyanation of imidazopyridine and indole. To the best of our knowledge, this is the first heterogeneous catalyst demonstrated for the thiocyanation of imidazo[1,2-a]pyridine. These findings will inspire further research in the development of high-performance D-A COFs as photocatalysts for organic transformations.

White-light driven sterilization based on chlorine-doped cuprous oxide for antibacterial food packaging

Microbial spoilage and pathogen contamination present significant challenges to food quality and safety. Incorporating photodynamic sterilization (PDT) into active packaging films, especially using white light-driven methods, is recognized as one of the most effective strategies to combat microbial contamination and extend shelf-life. Cuprous oxide (Cu2O) shows promise due to its suitable band gap for absorbing visible light, although its photocatalytic effectiveness is hindered by electron-hole recombination. In this study, a chlorine (Cl) doping strategy was investigated to enhance Cu2O’s PDT capabilities under visible light. This approach aimed to improve Cu2O’s band structure for generating reactive oxygen species (ROS) and to enhance charge carrier separation efficiency, thereby inhibiting recombination. The resulting Cl-doped Cu2O (Cl-Cu2O) exhibited enhanced antibacterial activity, which was integrated into a gelatin (Gel) and carboxymethylcellulose (CMC)-based food packaging film, referred to as the GC/Cl-Cu2O film. This innovative film provides a white light-driven active packaging solution designed to extend the shelf life of fruits by suppressing microbial growth. This approach not only addresses food safety concerns but also mitigates economic losses associated with food waste, offering a sustainable solution to enhance the quality and safety of perishable goods.

Investigating the effect of Cu underlayer and FTO etching towards photoelectrochemical performance enhancement of Cu2O photoelectrode

Cuprous oxide (Cu2O) exhibits potential as a photoactive material for photoelectrochemical water splitting, owing to its appropriate bandgap, efficient charge carrier separation, and ability to enhance solar-driven hydrogen production. This study investigates the influence of substrate etching, Cu underlayer and Cu2O electrodeposition time, and annealing time on enhancing the photoelectrochemical (PEC) performance. Electrodeposition and thermal oxidation techniques were used to fabricate the Cu2O/Cu/FTOe-A photocathode. It has been observed that FTO etching improves adhesion, light transmission, and efficiency. A Cu underlayer also impacts the PEC performance, wherein an ideal thickness of Cu leads to enhanced PEC performance. This study also focuses on the annealing time that leads to CuO layers and nanowires forming on the Cu2O surface. The structural and chemical changes before and after annealing are confirmed via XRD, XPS, AFM and FESEM analyses. UV–Vis analysis also reveals that the presence of Cu underlayer, FTO etching, and the annealing process affect the electrical properties and light absorption capacities of the Cu2O photoelectrode. Electrochemical impedance analysis (EIS) and Mott-Schottky analysis have provided insights into the enhanced charge transfer properties and band bending in the Cu2O/Cu/FTOe-A, resulting in enhanced PEC performance. Overall, this study provides significant insights into the understanding and enhancement of Cu2O/Cu/FTOe-A photocathodes for potential use in PEC water splitting applications.

Highly Efficient Organic/Silicon Hybrid Solar Cells with a MoO3 Capping Layer.

Organic/Si hybrid solar cells have attracted considerable attention for their uncomplicated fabrication process and superior device efficiency, making them a promising candidate for sustainable energy applications. However, the efficient collection and separation of charge carriers at the organic/Si heterojunction interface are primarily hindered by the inadequate work function of poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT:PSS). Here, the application of a high-work-function MoO3 film onto the n-Si/PEDOT:PSS surface leads to a notable enhancement in the device's built-in potential. This enhancement results in the creation of an inversion layer near the n-Si surface and facilitates charge separation at the interface. Simultaneously, it inhibits charge recombination at the heterojunction interface. As a result, the champion PEDOT:PSS/Si solar cell, which incorporates a MoO3 interface layer, demonstrates an efficiency of 16.0% and achieves a high fill factor of 80.8%. These findings provide a straightforward and promising strategy for promoting the collection and transmission of charge carriers at the interface of photovoltaic devices.

Micron-Scale Vertical MoS2/Porous g-C3N4 Piezocatalyst via a Precursor's Supramolecular Self-Template Architecture: Degradation and Hydrogen Evolution.

Piezocatalysis can effectively harvest various kinds of mechanical energy with high entropy from the environment and drive some redox reactions without light irradiation, where MoS2- and g-C3N4-based piezocatalysts are recent research hotspots. This study constructs an architecture of ordered melamine hydrochloride-cyanuric acid/MoO42- supramolecular precursor via self-assembly, serving as a self-template for in situ tight growth of vertically aligned micron-scale MoS2 on porous foam-like g-C3N4(CMx) under S vapor with a bioinspired rooting and sprouting-like process. Experiments, DFT calculations, and finite element simulations collectively confirm the high piezoresponse of the CMx with high exposure of active sites and enhanced mechanical energy collection. The vertical interfaces and built-in electric fields in the composite induce efficient charge carrier separation and transfer. The optimized CM0.77 efficiently degrades various organic dyes and antibiotic under dark ultrasound [rhodamine B (RhB): 0.47 s-1, methyl orange (MO): 0.05 s-1, methylene blue (MB): 0.21 s-1, and tetracycline hydrochloride (TC): 0.03 s-1] and achieves hydrogen evolution (2431 μmol·g-1·h-1). Under simulated water flow (10 L/min), the expanded CM0.77/Al2O3 porous foam ceramic (CM/alumina ceramic) purifier device degrades 95% of 400 mL of RhB within 25 min. The developed ordered vertical MoS2/g-C3N4 piezocatalyst demonstrates rapid pollutant degradation and efficient hydrogen evolution under water flow and ultrasound, providing new insights for constructing multidimensional piezoelectric composites for environmental remediation and clean energy production.

Fabrication of CoTiO3/MgIn2S4 S–scheme heterojunctions with efficient charge separation to enhance the photocatalytic activities of hydrogen generation and formaldehyde removal

The efficient separation of photoinduced charge carriers is a primary factor in the catalytic performance of photocatalysts. Constructing S-scheme heterojunctions is a prospective strategy to efficiently and spatially separate photoinduced charges while retaining strong oxidation and reduction capacities of the catalyst system. Herein, CoTiO3/MgIn2S4 (abbreviated x% CTO/MIS, where x% represents the mass ratio of CTO-to-MIS; x = 5, 10, 15, 20, and 25) heterojunctions were successfully synthesized using a hydrothermal method. These heterojunctions exhibited highly efficient and reusable visible-light photocatalytic properties for hydrogen (H2) generation and formaldehyde (HCHO) degradation. Notably, the 15 % CTO/MIS demonstrated an admirable H2 evolution activity of 631.77 μmol·g−1·h−1, with AQE = 2.25 % at λ = 420 nm, and an HCHO degradation rate of 67.18 %. The intermediate products generated during HCHO removal were identified applying in situ diffuse reflectance infrared Fourier transform spectroscopy. The exceptional catalytic performance of the synthesized materials was attributed to the boosted light absorption and utilization, rapidly separation, and transfer of photoproduced charge carriers, which resulted from the internal electric field of the S-scheme mechanism. Moreover, the S-scheme electron transfer pathway for the CTO/MIS catalyst system during the photocatalytic process was confirmed using electron spin resonance spectroscopy, free-radical capturing tests, density functional theory calculations, in situ X-ray photoelectron spectroscopy, and semiconductor energy band theory. The study offers an innovative perspective for establishing S-scheme heterojunctions with highly efficient and stable photocatalytic activity for H2 generation and HCHO removal.

Solar-driven Pt free hydrogen production and successive degradation of sulfasalazine using CuO/ZnO binary nanocomposites: Reaction kinetics and determination of reaction parameters using response surface methodology

BackgroundApproaches for sustainable, green, and expensive catalyst-free hydrogen production have not been explored extensively. Moreover, during photocatalysis, a lot of material gets wasted due to a lack of proper optimization of the reaction parameters to remove the toxic industrial effluents. MethodsHere in this study, we present the green synthesis of CuO/ZnO nanocomposites from the ethanolic crude extract of Oxystelma esculentum. The synthesized photocomposites were systematically characterized by Fourier transform infrared spectroscopy, zeta potential, x-ray diffraction, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and x-ray photoelectron spectroscopy. The performed analyses provided useful insights into identifying important functional groups, size, morphology, elemental composition, crystallinity, and defects in the synthesized photocomposites. Significant FindingsAfter characterization, the nanocomposites were evaluated for photocatalytic sulfasalazine (SSZ) degradation and hydrogen production. The response surface methodology (RSM) was employed to optimize SSZ's photocatalytic degradation. The optimized values of reaction parameters for the photocatalytic degradation of SSZ comprise pH = 4.06, SSZ dose = 47.75 mg/L, CuO/ZnO dose = 44.42 mg, and temperature = 23.60 °C. The rates observed in the hydrogen production (1136 µmolh-1g-1) were obtained without costly co-catalyst. The optimized values for hydrogen production include photocatalyst dosage = 50 mg, pH = 7, and time = 5 hours. These features signify the efficient separation of charge carriers between synthesized nanocomposites, resulting in exquisite activities.

Heterointerface engineering in mesoporous g-C3N4@MnFe2O4 photocatalysts for superior hydrogen (H2) evolution

Surfaces and interfaces play a pivotal role in heterostructures-based photocatalysts, which regulate the transfer, separation, and migration of photogenerated charge carriers. In this study, p-type MnFe2O4 nanoparticles (NPs) with complementary band structures were purposefully integrated with n-type porous g-C3N4 nanosheets (NSs) through precise interface engineering. The synergies in the g-C3N4@MnFe2O4 nanocomposites (NCs), leading to performance enhancement and functionalities, arise from their optimized mass fractions within the composite. The heterojunction interface formed in NCs possesses uniformly distributed mesopores (<4 nm), abundant active sites, and a high specific surface area (116 m2/g). Mesoporous heterojunctions improve photocatalytic activity by promoting the transfer of photogenerated electrons and holes to the photocatalyst surface. Notably, the optimized NCs, containing 20 wt% MnFe2O4, display the highest hydrogen evolution rate of 3.17 mmol g⁻¹ h⁻¹ (with methanol) and 5.77 mmol g⁻¹ h⁻¹ (with triethanolamine), which is many folds higher than bare MnFe2O4 and porous g-C3N4, using 1.0 wt.% of Pt as co-catalyst. The enhanced performance is corroborated by the efficient separation of photoinduced charge carriers, facilitated by an induced internal electric field arising from the Fermi level differences between the semiconductors. This study provides new insights into the advantages of designing and constructing mesoporous Z-scheme heterojunction photocatalysts for hydrogen evolution.

Microwave-Assisted Hydrothermal Synthesis of Photocatalytic Truncated-Bipyramidal TiO2/Ti3CN Heterostructures Derived from Ti3CN MXene.

TiO2/MXene heterostructure has garnered significant interest as a photocatalyst due to its large surface area and efficient charge carrier separation at the interface. However, current synthesis methods produce TiO2 without clear crystal faceting and often require complicated postprocessing step, limiting its practical applications. We demonstrate a facile and controlled microwave-assisted hydrothermal synthesis for transforming multilayered Ti3CN MXene to a truncated-bipyramidal TiO2/Ti3CN heterostructure. The resulting TiO2 nanocrystals at the Ti3CN surface exhibited crystalline anatase truncated bipyramids, exposing {001} and {101} facets. We further tailored an indirect optical band gap of the TiO2/Ti3CN heterostructure in the range of 3.17-3.23 eV by varying the hydrothermal synthesis time from 15 min to 5 h at a fixed temperature of 160 °C. Efficient charge separation allowed us to decompose 97% of methylene blue (MB) within 30 min of ultraviolet (UV) light irradiation, ∼3.9-fold faster than the benchmark P25, higher than any other TiO2/MXene heterostructures. With simulated white light, we achieved over 60% efficiency of the dye decomposition within 2 h of irradiation, which resulted in 1.5-fold faster kinetics than P25. We also observed a similar excellent performance of Ti3CN-derived TiO2 in decomposing various persistent synthetic dyes, including commercial textile dye, methyl orange, and rhodamine B. In conclusion, our study provides a strategy for utilizing MXene chemical reactivity to produce highly crystalline optically active TiO2/Ti3CN heterostructure. The developed heterostructure can serve as an efficient photocatalyst for the degradation of organic pollutants.

Persistent luminescent ZnAl-LDH nanosheets for all-weather degradation of nitenpyram and tetracycline: Superoxide radical induction, life cycle analysis and engineering applications

Photocatalysts designed for all-weather applications, capable of efficient charge carrier separation, are set to transform the adoption of photocatalysis-driven advanced oxidation processes in wastewater management. In this investigation, an energy-storing ZnAl-LDH@SrAl2O4:Eu2+, Dy3+ (SALDH) was synthesized successfully, optimized for the photocatalytic selective degradation of NTP and tetracycline hydrochloride (TC) under varying weather conditions, with 100 % degradation of both NTP and TC within 75 min. Remarkably, SALDH demonstrates energy storage capabilities that markedly reduce energy demands relative to traditional photocatalytic approaches. The primary reactive species identified were O2−, and the Fukui index, computed via density-functional theory (DFT), identified the specific interaction sites of O2− on NTP molecules. Utilizing the energy retention properties of SALDH, a novel, environmentally friendly device was engineered for processing organic pollutants in agricultural wastewater. This system harness the energy from solar radiation to induce the oxidation of pollutants. The experiments that were performed in the both artificially prepared lab-scale and actual agricultural WWT plants indicated the degradation efficiencies of 36 % and 37 %, respectively. As seen during the day, both SALDH and persulfate were capable of effectively decomposing organic contaminants; at night, the SA’s luminescence maintained the oxidative ability of ZnAl-LDH. Meanwhile, SALDH combines the corrosion resistance of ZnAl-LDH with good metal compatibility, enabling SALDH to effectively improve the photostability of long afterglow. This work contributes to the existing knowledge on the degradation of organic pollutants by efficient photocatalysts and points to possible implementations in water treatment processes.

Enhanced piezocatalytic RhB degradation with ZnSnO3 Nanocube-modified Bi4Ti3O12 composite catalyst by harnessing ultrasonic energy

With the increasing demand for effective methods to address environmental pollution, piezocatalysis has emerged as a promising approach for pollutant degradation under mechanical energy. However, the development of highly efficient piezocatalytic materials remains a challenge. This study aimed to increase the piezocatalytic activity of bismuth titanate (Bi4Ti3O12) by modifying it with zinc stannate (ZnSnO3) nanocubes. The composite catalysts were synthesized using a straightforward deposition and calcination process. The calcination process ensured the tight adhesion of ZnSnO3 nanocubes to the Bi4Ti3O12 surface, while facilitating strong interactions between ZnSnO3 and Bi4Ti3O12, which enhanced electron transfer and heterojunction structure formation. Band structure analysis indicated that Bi4Ti3O12 has higher conduction band and valence band potentials than ZnSnO3, forming a type-II heterojunction. Bi4Ti3O12 possesses a higher Fermi level than ZnSnO3, resulting in interfacial electron drift and formation of a built-in electric field, which further promotes the directional transfer and separation efficiency of charge carriers within the composite catalyst. This hypothesis was confirmed by surface photovoltage spectroscopy, piezoelectric current response, and electrochemical analysis. Consequently, the ZnSnO3/Bi4Ti3O12 composite exhibited significantly improved piezocatalytic performance in RhB degradation, achieving a degradation efficiency of 80 % within 90 min under ultrasonic vibration. The degradation rate of the optimal sample was 8.2 times that of Bi4Ti3O12 and 6.3 times that of ZnSnO3. Additionally, experiments to detect reactive species were conducted to elucidate the mechanism behind the piezocatalytic RhB degradation. Holes and hydroxyl radicals were the main reactive species. This study may offer new insights into the design of efficient piezocatalytic materials.

Full-spectral response of mesoporous Z-scheme nanoheterojunction NaYF4:Yb,Tm@ZnO/BiOI photocatalysts for simultaneous contaminant and pathogen elimination in wastewater

The increasing contamination of water bodies demands effective and economical solutions for wastewater treatment. This study introduces a novel Z-scheme photocatalyst, NaYF4:Yb,Tm@ZnO/BiOI (UZB), synthesized via a simple chemical route. UZB exhibits exceptional photocatalytic degradation efficiencies of 95.1%, 88.7%, and 56.3% for methyl orange under full spectrum, visible, and near-infrared light, respectively. The integration of heterostructures within UZB promotes efficient charge carrier separation, significantly boosting its photocatalytic activity. When applied to actual wastewater, UZB markedly reduces chemical oxygen demand (COD) and total organic carbon (TOC) by 94.1% and 53.2%, respectively, and also effectively decreases turbidity and ammonia concentrations. Additionally, UZB shows strong antibacterial effects against S. aureus and E. coli, with inhibition rates of 93.9% and 92.0%, though some cytotoxicity is noted. These results underscore UZB's potential as a highly efficient photocatalyst for the simultaneous removal of organic pollutants and pathogens from wastewater, supporting its application in industrial water treatment systems.

In-situ construction of 3D/2D ZnIn2S4/Ni-MOLs: Highly efficient visible-light-driven photocatalytic heterojunction in hydrogen evolution

Photocatalytic water splitting for hydrogen production is a sustainable and environmentally friendly technology. However, the rapid recombination of photo-induced electrons and holes results in low hydrogen production activity of photocatalysts. Constructing low-cost and high-efficiency heterojunctions is an imperative strategy to address the current challenges in photocatalytic hydrogen production. This study presents a novel binary heterojunction photocatalyst constructed of ZnIn2S4 nanoflowers and Ni-MOLs nanosheets, which was successfully synthesized via an in-situ hydrothermal method. Furthermore, the ZnIn2S4/Ni-MOLs heterojunction exhibited an excellent visible light absorption performance, which was conducive to hydrogen production under visible light irradiation. Specifically, the optimized ZnIn2S4/Ni-MOLs exhibited a remarkable hydrogen evolution rate of 4.75 mmol·g−1·h−1 under visible light irradiation, which was about 95 times and 8 times higher than that of pure Ni-MOLs and ZnIn2S4, respectively. Additionally, the catalyst exhibited excellent stability in five recycling cycles test, and the apparent quantum efficiency (AQE) of the optimized ZnIn2S4/Ni-MOLs had reached 23.3 %. The formation of the ZnIn2S4/Ni-MOLs heterojunction significantly enhanced photocatalytic activity by promoting efficient charge carrier separation, exposing more active sites and enhancing absorption of visible light. The experimental characterization and density functional theory (DFT) calculations revealed that the synergistic effect within the ZnIn2S4/Ni-MOLs heterojunction significantly facilitated the directional transfer of electrons from ZnIn2S4 to Ni-MOLs, achieving efficient charge carrier separation. This study not only synthesized an efficient photocatalyst for hydrogen production under visible light but also provided a novel strategy for constructing effective and stable ZnIn2S4-based or MOLs-based heterojunction photocatalysts.

Rational construction p-n heterojunction Ni(OH)2/NiS2 on g-C3N4 nanosheet to promote the charge carriers separation efficiency for boosting photocatalytic hydrogen evolution

The Ni(OH)2/NiS2/g-C3N4 hybrid with sandwich-like structure was successfully designed and synthesized through a solvothermal and condensation reflux method. Furthermore, it should be noted that the p-type Ni(OH)2 was in situ generated on the surface of the n-type NiS2, because the Ni2+ of the Ni(OH)2 came from the NiS2. Therefore, the p-n heterojunction was constructed between the interface of the Ni(OH)2 and NiS2 in the hybrid. Furthermore, the results revealed the optimized Ni(OH)2/NiS2/g-C3N4 hybrid displayed superior H2 evolution property than that of the g-C3N4, NiS2/g-C3N4, and Ni(OH)2/g-C3N4 illuminating with visible-light or simulated-sunlight. The apparent quantum yield (AQY) of Ni(OH)2/NiS2/g-C3N4-6 % at 360, 380 and 400 nm were 1.65 %, 1.31 % and 1.05 %, respectively. Moreover, the resultant Ni(OH)2/NiS2/g-C3N4-6 % hybrid both displayed satisfactory photochemistry durability. Besides this, according to the microstructure and photoelectric property characterizations, theoretical calculation, and in situ XPS test, the promoted H2 evolution property of the ternary catalyst was profit from the synergy impact of the particular sandwich-like structure, and p-n heterojunction. Because they could memorably boost the carriers’ separation efficiency, and offer abundant active sites for H2 production.

Wide-spectrum-responsive MoS2/WS2 decorated Al-MOF nanohybrid with dual S-scheme heterojunction in facilitating sonophotocatalytic tetracycline abatement and pharmaceutical effluent treatment

The work investigates the application of a MoS2/WS2 decorated Al-MOF nanocomposite for the degradation of tetracycline (TC) in water by sonophotocatalysis. The nanocomposite revealed a dual S-scheme heterojunction that has a broad-spectrum response, resulting in a better efficiency for the degradation of TC (97%). The synergy index during sonophotocatalysis was measured to be 2.79. Moreover, the nanocomposite was effectively used to actively regulate the concentration of TC (73.2%) and other pollutants in pharmaceutical wastewater. An extensive analysis was performed to examine the impact of various significant parameters, including pH, catalyst dosage, TC concentration, and others. Sonophotocatalysis outperforms both sonocatalysis and photocatalysis, exhibiting pseudo-first-order kinetics. The improved performance can be credited to the formation of a dual S-scheme heterojunction, which facilitates the efficient transfer and separation of charge carriers that are stimulated by visible light exposure. Furthermore, the nanocomposite exhibited exceptional stability and demonstrated significant potential for being reused. The results suggest that the MoS2/WS2 decorated Al-MOF nanocomposite shows promise as a feasible choice for efficient and eco-friendly water treatment processes.

Rapid room temperature synthesis of CuBi2O4 via ball-milling strategy boost light-driven persistent activation of hydrogen peroxide

Photo-Fenton technology with the superiorities of photocatalysis and traditional Fenton catalysis can improve the catalytic efficiency of photocatalytic materials and thus achieve efficient degradation for organic pollutants. However, exploring a low-cost catalyst with excellent catalytic performance using a simple method remains a challenge. In this work, CuBi2O4 photocatalyst synthesized by a mechanical ball-milling strategy (M-CuBi2O4) was exploited and used for tetracycline (TC) degradation. The impact of solution pH and H2O2 dosage on the photo-Fenton degradation efficiency of M-CuBi2O4 towards TC was investigated. M-CuBi2O4 exhibited significant 85.1% of photo-Fenton catalytic activity for TC removal, which was 9.35 times higher than that of CuBi2O4 synthesized by hydrothermal method (H-CuBi2O4). The enhanced catalytic performance of M-CuBi2O4 was due to the superior charge carrier separation efficiency, wider photo-response range and increased generation of active species. The primary active substances involved in the photo-Fenton reaction for TC degradation were determined to be hydroxyl radicals (•OH), superoxide radicals (•O2-), and singlet oxygen (1O2). This study provides a streamlined and rapid approach for macro preparation of high-performance photocatalysts for dealing with antibiotic-contaminated wastewater.

Synthesis of Quinone‐Amine‐Linked Covalent Organic Frameworks for Boosting the Photocatalytic Removal of Uranium

AbstractCompared to imine covalent organic frameworks (COFs), the superior stability of amine‐linked COFs renders them more suitable for long‐term harsh real‐world environments. Their numerous amine sites can serve as functional groups or be subjected to post‐modification to further enhance the performance of the material. However, the assortment and abundance of amine‐linked COFs via currently lacking due to restricted monomer varieties and synthetic methods. Herein, this study presents an innovative approach for synthesizing quinone‐amine‐linked COFs by directly combining 2,5‐dihydroxy‐1,4‐benzoquinone (DHBQ) with various amine monomers and introduce a novel photocatalyst, DHBQ‐TAPP‐COF, specifically tailored to efficiently reduce uranium in harsh environments. DHBQ‐TAPP‐COF features a unique donor–acceptor structure, with the DHBQ units serving as acceptors because they contain abundant oxygen atoms that facilitate metal ion coordination, thereby enhancing charge carrier separation, carrier utilization, and uranium reduction efficiency. The quinone‐amine linkages offer improved stability, extended π‐conjugation, heightened local polarity, and conductivity, which enable efficient carrier transfer within the material and thus enhance the overall performance of the uranium photocatalyst. The proposed photocatalyst can efficiently reduce U(VI) without sacrificial agents or decomposition to precipitate UO2 at a recovery rate exceeding 98%. This catalyst provides an efficient and convenient strategy for the stable and high‐performance photocatalytic reduction of uranium.

Hydrogen bond-induced supramolecular self-assembly strategy to fabricate ultra-dispersed Cu-loaded porous tubular graphitic carbon nitride with rich nitrogen vacancies and CuNx sites for efficient photo-Fenton catalysis

The low utilization of visible light and easy recombination of charge carriers of graphitic carbon nitride (CN) restrain its application as photo-electron donor and metal site support in photo-Fenton system. Herein, a hydrogen bond-induced supramolecular self-assembly strategy was created to fabricate an ultra-dispersed Cu-loaded porous tubular CN composite (CA-Cu/TCN) by the hydrothermal–pyrolysis method with citric acid (CA) as initiator and chelating agent. CA-Cu/TCN with rich nitrogen vacancies (NVs) and abundant ultra-dispersed CuNx sites exhibited narrow bandgap, favorable visible light absorption capability, and high separation and transfer efficiency of charge carriers. CA-Cu/TCN effectively catalyzed the activation of H2O2 for generating abundant reactive oxygen species under visible light irradiation, contributing to efficient degradation of ciprofloxacin (CIP) with removal rate of 95.9 % and kinetic rate constant of 0.0948 min−1. The superior catalytic activity of CA-Cu/TCN can be ascribed to the effective transport of photogenerated electrons, high specific surface area, atomically dispersed Cu species, and enriched surface NVs. The mechanism of photo-Fenton catalytic degradation of CIP and possible degradation pathways were proposed as the dominant role of 1O2. Toxicity evaluation of CIP and intermediates indicated that the degradation of CIP was a gradual detoxification process. This work offers a novel self-assembly strategy to design and synthesize highly active and sustainable visible light-driven photo-Fenton catalysts for effectively degrading organic pollutants.