Light Irradiation Research Articles

Environment Friendly Cr₂O₃ Nanoparticles from Opuntia dillenii for Visible-Light Photocatalysis and Antimicrobial Defense Against Waterborne Pathogens

Water pollution is a serious problem, especially in developing and underprivileged countries; it has seriously affected ecosystems and human health. This work focuses on the environmentally friendly synthesis of Cr2O3 nanospheres using an extract from Opuntia dillenii plant leaves. This study identifies the potential of Cr2O3 nanospheres for Rose Bengal (RB) degraded pollutants. The synthesized Cr2O3 nanospheres have a bandgap of 2.93 eV and a highly crystalline structure. This makes them a better photocatalyst for degradation RB. FTIR, XRD, FESEM, TEM, and EDX characterized the crystalline Cr2O3 nanospheres. Under visible light irradiation, the Cr2O3 nanospheres degraded RB by 80% in 40 min. The results of this study suggest that Cr2O3 nanospheres may be suitable for the environment and can perform best as photocatalysts for breaking down complex structures. The results also show that using Cr2O3 nanospheres, which are safe for the environment, could be a long-lasting and effective way to clean up complex organic pollutants in aquatic ecosystems. This study highlights the potential of Cr2O3 NPs mixed with O. dillenii extract as a good candidate.

Mesoporous I-doped-g-C3N4 with C Vacancies as Superior Visible-light-driven Photocatalyst for Removal of Tetracycline Antibiotic

The discovery of g-C3N4 (GCN) has attracted great attention for antibiotic pollutants from wastewater. Nonetheless, photocatalytic performance of GCN suffers from rapid recombination, limited surface area, and restricted under visible light irradiation. In this work, different concentrations of mesoporous I-doped GCN were synthesized. Mesoporous I-doped GCN with 0.50g of I dopant (GCN-I0.50) manage to photodegrade 99.8% of TC within 150min under visible light (λ > 420nm). The tetracycline (TC) antibiotic photodegradation rate increased by 2.64 times than that of parent GCN. It is proven that I-dopant and generation of C vacancy provides extra electrons to reconstruct the GCN network. This led to a stronger driving force in photo-oxidation photodegradation. The C vacancy also acts as a trap to prevent fast charge recombination. Subsequently, the substantial surface area and mesoporous nature of GCN-I0.50 (63.76 m2/g) facilitate the breakdown of a greater quantity of TC pollutants. In addition, the structural distortion of GCN-I0.50 has promoted n-π* transition, extended photoactivity to visible light region due to smaller band gap (2.45eV). The GCN-I0.50 photocatalyst significantly improved the TC photodegradation rate with good stability.

Construction of hollow core-shell ZnO@Co3O4 p-n heterojunction for CO2 cycloaddition under visible light irradiation

In comparison to a single semiconductor, constructing p-n heterojunctions represents an efficient strategy for enhancing photocatalytic activity because of their advantages in accelerating charge separation and promoting photoabsorption. Herein, we propose a novel metal–organic framework (MOF)-assisted and controlled pyrolysis strategy for constructing a hollow core-shell p-n heterojunction photocatalyst ZnO@Co3O4. It is worth noting that the hollow core-shell heterojunction not only provides abundant active sites but also significantly facilitates the separation of photogenerated charge carriers and accelerates electron transfer. Benefiting from the above advantages, the optimized ZnO@Co3O4(400,2), obtained by pyrolysis at 400 ℃ for 2h using Zn-MOF@Co-MOF as a precursor, exhibits high activity for the cycloaddition of CO2 and epichlorohydrin, resulting in a 94% yield of 4-(chloromethyl)-1, 3-dioxolan-2-one under 1bar CO2 pressure and visible light irradiation for 2h, which is significantly superior to those of ZnO(400,2) (5%), Co3O4(400,2) (38%), and the physically mixed counterparts (55%). This work provides insightful guidance for designing efficient photocatalysts aimed at CO2 cycloaddition, thereby achieving solar to high-value-added chemical conversion efficiencies.

Innovative synthesis and practical application of graphitic carbon nitride/α-zirconium phosphate in visible light-activated Knoevenagel condensation

To advance the development of efficient photocatalysts activated by visible light for environmental applications. We employed a simple approach to synthesize g-C3N4/α-ZrP composite in different mass ratios, followed by comprehensive characterization through several techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope coupled with energy dispersive X-ray spectroscopy (SEM/EDS), and UV–Visible diffuse reflectance spectra (DRS). Furthermore, the g-C3N4/α-ZrP with mass ratio 6:1 was demonstrated high performance catalytic activity in Knoevenagel condensation (Yield 88 %–96 %) in a short reaction time (5–20 min) under visible light irradiation. The use of g-C3N4/α-ZrP has transformed the traditional synthesis of carbon–carbon double bonds, offering improved reaction rates and reduced by-products. These next-generation photocatalysts also exhibit remarkable properties that facilitate the activation of substrates under milder conditions, opening up new possibilities for green and sustainable synthesis. This advancement contributes to the development of environmentally friendly and efficient synthetic methodologies.

Characterization of Ti-MOF derived TiOx assembled with different carboxylic acid organic ligands and differences in their CO2 photothermal catalytic reduction performance

The photothermal catalytic conversion of carbon dioxide into fuel gas is a promising technology for simultaneously addressing environmental and energy challenges. Currently, widely used metal oxide-based catalysts, such as TiO2, often show significant performance variations depending on the preparation methods. Therefore, developing metal oxides with superior photothermal catalytic properties is a key approach to producing high-performance composite catalysts. This article discusses the preparation of high-performance metal oxide catalysts derived from MOFs. By regulating four different carboxylic acid organic ligands to assemble with Ti-O clusters into various precursors, TiOx was derived and prepared. Techniques such as XRD, infrared spectroscopy, XPS,TEM, SEM, N2 adsorption–desorption analysis, CO2-TPD, H2-TPR, PL spectrum, Raman spectra, UV–visible diffuse reflectance spectroscopy, photoelectrochemical characterization, and others were used to comprehensively explore the structure, surface properties, and photoelectric properties of the derivatives influenced by the organic ligands. Derivatives were subjected to photothermal catalytic reduction of carbon dioxide in hydrogen rich gas without metal loading, and the intermediate pathway of the reaction was investigated through in situ DRIFTS spectra. Research has shown that organic ligands have a significant impact on the morphology, surface properties, and optoelectronic properties of derivatives. The TiOx derived from the precursor assembled with 2-aminoterephthalic acid as an organic ligand has a larger specific surface area, abundant oxygen vacancies, excellent photoelectric conversion ability, and surface electron migration performance. Under the condition of coupled light irradiation at 400 ℃, a CO yield of 4944.81 μmol/g was achieved, with a selectivity of 99.89 %. The reaction follows the formate pathway. This study provides valuable reference for the development and modification of high-performance TiO2 based catalysts.

Targeting active sites nickel-porphyrin over BiOBr nanosheets with excellent charge separation for accelerated photoreduction reactions

The energy crisis and environmental pollution severely constrained the sustainable development of society. Herein, nickel-porphyrin active sites have been integrated over BiOBr for enhanced photocatalytic CO2 reduction and Cr(VI) removal. The optimized NiTMCPP/BiOBr-2 photocatalyst exhibits CO generation rate of 14.14 μmol g−1 under irradiation for 5h, which is around 2 times compared with BiOBr. Meanwhile, Cr(VI) removal efficiency over NiTMCPP/BiOBr-2 is 97.72% under visible light irradiation for 40min, which shows enhanced photoreduction ability compared with BiOBr (77.31%). Numerous experimental results indicate that the improved photocatalytic activity for NiTMCPP/BiOBr-2 is mainly owing to the enhanced transport efficiency of photoinduced carriers after the loading of Ni-porphyrin. Especially, the central Ni2+ active site of porphyrin can accept excitation electrons, thus enhancing photoreduction performance. Furthermore, the mechanisms for photocatalytic CO2 and Cr(Ⅵ) reduction were further discussed via in-situ FT-IR and capture experiments. This work gives a promising way to design hybrid photocatalysts for energy conversion and environmental treatment.

NaBiO3/g-C3N4 Z-type heterojunction modified by Ag-anchorage to enhance the photocatalytic performance

NaBiO3/Ag/g-C3N4 photocatalyst with Z-type heterostructure was developed and synthesized using photo-deposition and hydrothermal treatment methods, yielding a composite material with high REDOX ability. Because Ag in the NaBiO3/Ag/g-C3N4 composite system served as an electron capture center, the separation efficiency of photoexcited carriers was greatly increased, and the carrier lifetime was extended, as indicated by photoelectrochemical analysis. The results show that NaBiO3/Ag/g-C3N4 had much superior photocatalytic activity than monomer materials under visible light. Under visible light irradiation, the 0.1g 6% NaBiO3/Ag/g-C3N4 photocatalyst removed 95% of tetracycline in 60min. The reaction major active components were ∙O2-, ‧OH and h+, as acquired by active species capture experiments and EPR tests. Based on this, the manufacturing pathway for active compounds showed the electron transfer pathway and photocatalytic mechanism of Z-type heterojunction.

Light harvesting S-scheme g-C3N4/TiO2/M photocatalysts for efficient removal of hazardous moxifloxacin

The development of advanced photocatalysts with enhanced efficiency for environmental remediation is critical for addressing persistent organic pollutants like Moxifloxacin. In this study, we present a novel S-scheme heterojunction g-C3N4/TiO2/M photocatalyst designed to optimize light harvesting and charge separation for the effective degradation of Moxifloxacin. The innovative S-scheme configuration enables superior charge transfer dynamics by retaining potent photogenerated electrons in the conduction band of TiO2 and holes in the valence band of g-C3N4, significantly improving photocatalytic performance compared to conventional Type-II systems. Heterogeneous photocatalysis, particularly using TiO2-based materials, offers a promising approach. Here, we synthesized TiO2 hybridized with metal-doped g-C3N4 (GCNTM) via a simple hydrothermal method. The fabricated nanocomposites were characterized using SEM, XRD, FTIR, and UV–Vis (DRS). These GCNTM nanocomposites were employed for the degradation of hazardous Moxifloxacin (MXF) under visible light. Detailed analysis of the photocatalytic mechanism reveals that the synergistic interaction between g-C3N4, TiO2, and the co-catalyst M not only broadens the light absorption spectrum but also enhances the separation and lifespan of charge carriers. Among the synthesized materials, GCNTLa demonstrated the highest degradation efficiency, achieving 96 % removal of MXF. This enhanced activity is attributed to the effective suppression of charge recombination, leading to the generation of reactive species responsible for MXF degradation. Additionally, GCNTM showed remarkable stability and reusability, with only a 6 % reduction in efficiency after five cycles, confirming its high reusability and mechanical stability. Our S-scheme photocatalyst demonstrates a marked increase in the degradation rate of Moxifloxacin under visible light irradiation, highlighting its potential for practical environmental applications.

Fabrication of ZnIn2S4/CeO2 S-scheme heterojuntion for the enhanced removal of tetracycline under visible light irradiation

A series of S-scheme ZnIn2S4/x-CeO2 heterojunction were designed and fabricated through in-situ precipitation and hydrothermal method. XRD, SEM, TEM, EDX, XPS, UV-vis DRS and adsorption-photocatalytic techniques were employed to investigate its crystal phase structure, morphology, size, elemental composition, photo-response property and elimination ability for tetracycline. XRD analysis revealed CeO2 and ZnIn2S4 in ZnIn2S4/x-CeO2 sample presented cubic and hexagonal phase structure, respectively. SEM and TEM images indicated that CeO2 particles with irregular-shaped of around 20nm were attached on the smooth surface of ZnIn2S4 microparticles with ca. 4 μm. All the as-synthesized ZnIn2S4/x-CeO2 samples could harvest more visible-light and the absorption edges were red-shifted in comparison with pure CeO2. ZnIn2S4/0.3-CeO2 sample exhibited remarkably enhanced photocatalytic performance and its removal efficiency for tetracycline reached 87.29% within 100min. The detailed experimental and DFT calculation indicated that the enhanced photocatalytic property was mainly ascribed to the synergistic effect of wide light-response range, suitable band position and successful fabrication of S-scheme heterostructure, which was in favor of rapid transfer and available separation of photo-generated e-/h+ pairs. The scavenger experiments and the ESR data revealed that the •O2– and h+ active species played the dominant role in tetracycline removal over ZnIn2S4/0.3-CeO2 system. In addition, the as-synthesized ZnIn2S4/0.3-CeO2 samples had excellent stability and the removal efficiency still reached 70.73% after being repeatedly used for 4 times. Furthermore, the possible enhanced photocatalytic mechanism over ZnIn2S4/x-CeO2 was proposed to get a better understanding of photocatalytic process. This work provided the guidance to fabricate CeO2-based heterojunction with promising prospect for the efficient elimination of antibiotic residues from wastewater.

Synthesis and characterization of multi-responsive iron oxide nanoparticles: Evaluation of antibacterial properties and photocatalytic activity

Cape gooseberry (CG) plant leaf extract-mediated iron oxide nanoparticles (CG-IO NPs) were fabricated for antibacterial research. The ideal concentration of the precursor salt, pH (11) of the reaction mixture, reducing agent to precursor salt ratio, and the production time of iron oxide nanoparticles were 5 mM, 9.0, 3:7, and 25 min, respectively. The iron oxide nanoparticles were tested using ultraviolet–visible absorption spectroscopy, photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric/differential thermal analysis (TG/DTA), and Fourier transform infrared (FTIR) spectroscopy. FTIR spectroscopy was used to identify functional groups of the compounds, including the carbonyl, CH, and OH bands that reduced and produced nanoparticles. The size and shape of the synthesized CG-IO NPs were determined by TEM and dynamic light scattering, with the median and mean size of 13.9 nm and 15.8 nm, respectively. The thermal stability of the synthesized CG-IO NPs was assessed using TG/DTA in a nitrogen atmosphere. The elements and oxidation states of the CG-IO NP components were examined by XPS. The luminosity of the CG-IO NP was examined using PL spectroscopy. The synthetic CG-IO NPs exhibited strong antibacterial effects against dangerous bacteria, such as Salmonella enterica (S. entirica), Escherichia coli (E. coli), Streptococcus agalactiae, and Staphylococcus aureus. CG-IO NPs assisted in water reclamation by decomposing Malachite Green dye under solar light irradiation.

Investigations on Photodegradation and Antibacterial Activity of Mixed Oxide Nanocrystalline Materials

In this study, we synthesized cobalt-doped molybdenum supported on silica (Co/MS) nanocomposites with varying concentrations of cobalt (1, 5, 10, 15, and 20 wt%) using the sol-gel method. We investigated their physico-chemical properties, photocatalytic activity, and antimicrobial efficacy. The synthesized nanocomposites were characterized using a range of techniques, including X-ray powder diffraction (XRD) to determine crystal structure, UV-vis spectroscopy for optical properties, Fourier transform infrared spectroscopy (FT-IR) for functional group analysis, and scanning electron microscopy coupled with energy-dispersive X-ray microanalysis (SEM-EDX) for morphological and elemental composition analysis. The photocatalytic performance of these catalysts was assessed by their ability to degrade organic dyes, specifically methyl orange and methylene blue, under visible light irradiation. Our results demonstrated that the photocatalytic efficiency increased with higher cobalt content, with the 20 wt% Co/MS nanocomposite showing the highest degradation rates. Additionally, we evaluated the antibacterial activity of the nanocomposites against a range of microorganisms, including Gram-positive and Gram-negative bacteria, as well as fungal species. The 20 wt% Co/MS nanocomposite exhibited superior antimicrobial activity compared to the other samples, indicating its potential for applications in environmental remediation and antimicrobial treatments.

LSPR-assisted W18O49/ZnO S-scheme heterojunction for efficient photocatalytic CO2N-formylation of aniline

Designing highly efficient photocatalyst for the valorization of CO2 is an ideal strategy to reduce greenhouse gas emissions and utilize solar energy. In this study, a S-scheme heterojunction photocatalyst is fabricated by solvothermal impregnation of ZnO on W18O49 for photocatalytic CO2N-formylation of aniline. The localized surface plasmon resonance effect of W18O49 improves the absorption capacity for long-wave light significantly, and the hot electrons generated in W18O49 with a high energy can migrate to the conduction band of ZnO and thus enhance the photocatalytic reduction ability. Meanwhile, the S-scheme heterojunction facilitates the separation of photoinduced charge carriers and preserves the redox ability of W18O49/ZnO composite photocatalyst. The conversion of aniline reaches 99.1% after 5 h reaction under visible light irradiation at room temperature with an N-formylaniline selectivity of 100%. A possible photocatalytic reaction mechanism is proposed. This study paves a promising way for the design of highly efficient photocatalyst and the sustainable utilization of CO2.

Chitosan-BODIPY fluorescent composite materials for photodynamical antibacterial and therapy

Chitosan-based fluorescent copolymers containing borodipyrromethene (BODIPY) were synthesized and investigated. In this work, fluorescent compound (BOD-4) containing -C ≡ CH was synthesized firstly. Subsequently, chitosan (CS)-based polymer CS-I was obtained through the -NH2/-C ≡ C click reaction between BOD-4 and CS. Thirdly, CS-Py was prepared via Suzuki reaction between CS-I and pyridine. Finally, the synthesis of macromolecular photosensitizers, i.e. CS-Me and CS-Bn, was achieved by pyridinium salt formation. CS-Me and CS-Bn could produce reactive oxygen species (ROS) when exposed to white light, demonstrating superior light utilization efficiency. This strategy not only utilizes the photodynamic ability of photosensitizing molecules but also takes advantage of chitosan's biocompatibility and antibacterial efficacy. The photodynamic antimicrobial activities of the macromolecular photosensitizers have been tested against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). CS-Me and CS-Bn exhibited not only the inherent antibacterial properties but also photodynamic capabilities, which significantly enhance their antibacterial effectiveness. Under white light irradiation, bacteria can be effectively eradicated. When made into a film by loading CS-Me and CS-Bn onto transparent band-aid, excellent photodynamic antibacterial properties were obtained. CS-based photosensitizers maintain the biocompatibility and antibacterial properties of CS. In addition, they expand the scope of chitosan's application in photodynamic therapy (PDT) as well.

Dye-sensitized n-n heterojunction {001}TiO2@NH2-MIL-101(Fe) for degradation of Rhodamine B under visible light

The {001}TiO2@NH2-MIL-101(Fe) heterojunctions (MT-x) crafted by the fusion of components {001}TiO2 and NH2-MIL-101(Fe) possesses an optimally positioned conduction band. Consequently, MT-x is capable of sensitizing Rhodamine B (RhB) and effectuating its degradation via a photocatalytic mechanism that is driven by visible light irradiation. Specifically, the n-n heterojunction designated as MT-3 achieved a RhB removal rate of 94.45% within a 3-hour period, which corresponds to a 5.4-fold and 2.2-fold enhancement over the degradation rates observed for {001}TiO2 and NH2-MIL-101(Fe), respectively. Photo-electrocatalytic performance analyses showed that the n-n heterojunction MT-3 effectively inhibited electron-hole pair recombination. Moreover, the intimate interfacial contact between monomer materials enhanced the separation and transfer of photogenerated carriers, which indicates that MT-3 has excellent photocatalytic performance. The free radical trapping and EPR results indicated that ·O2- plays a major role in the photocatalytic degradation of RhB by MT-3, followed by h+ and ·OH. Furthermore, high-resolution liquid chromatography-mass spectrometry was employed to investigate photodegradation intermediates. The destruction of the RhB structure significantly reduced the environmental pollution associated with organic dye. The MT-x heterojunction exhibits remarkable potential for practical applications in organic contaminants removal.

Preparation and investigation of physicochemical properties of g-C3N4/LaCoO3 heterostructure for photocatalytic dye degradation

Photocatalytic decomposition of pollutant is the most optimal approach for the wastewater remediation. Nevertheless, the development of a catalyst that is both cost-effective and extraordinarily active remains a substantial challenge. The g-C3N4/LaCoO3 heterostructure were prepared by different weight percentages of g-C3N4 (15, 30, 45, 60, and 75 wt%). The g-C3N4 and LaCoO3 were exhibits hexagonal and rhombohedral crystal structure respectively. The g-C3N4/LaCoO3 heterostructure exhibits tiny particles were anchored over the coarse like structure. The g-C3N4/LaCoO3 heterostructure promote visible light harvest and inhibit charge carrier recombination than the bare LaCoO3 and g-C3N4 and which helps to enhance the organic pollutant elimination performances. The g-C3N4/LaCoO3 heterojunction exhibits superior methylene blue degradation when compared to bare LaCoO3 and g-C3N4. Furthermore, the composite of LaCoO3/g-C3N4–60 wt% exhibits higher photocatalytic activity and exceptional stability were observed under visible light irradiation.

Antimonene and bacterial outer membrane vesicle modification nanoplatform enhanced photothermal immunotherapy

Photothermal therapy and immunotherapy have attracted widespread attention because of their great advantages for enhancing the effectiveness of cancer treatment and reducing side effects. However, they also have their own shortcomings. Based on the characteristics of photothermal therapy and immunotherapy, functionalized nanoparticle-mediated photothermal-immune synergistic therapy can effectively compensate for their respective deficiencies and produce synergistic effects. Herein, we designed a bioengineering strategy to construct a novel anticancer nanoplatform (AM@DSPE-PEG/OMV) for photothermal-immunotherapy of cancer by coating bacterial outer membrane vesicles onto polyethylene glycolized antimony alkene nanosheets (AM@DSPE-PEG). Bacterial outer membrane vesicles (OMV) have emerged as potent activators of the host immune response in the realm of cancer immunotherapy. In conjunction with near-infrared light irradiation, antimonene nanosheets demonstrate remarkable photothermal properties, thereby instigating immunogenic cell death and facilitating the release of both antigens and "danger signals". This dual mechanism facilitates the thermal ablation of primary tumors, thereby eliciting an immune response. Additionally, these processes further stimulate the maturation of dendritic cells, consequently augmenting antigen presentation and fortifying the immune response. Thus, the synergistic utilization of OMV and antimonene nanosheets holds promise in enhancing the efficacy of immunotherapeutic interventions for cancer. We demonstrated that AM@DSPE-PEG/OMV can passively target tumors, exhibit excellent biocompatibility and superior photothermal conversion efficiency, significantly upregulate the secretion levels of cellular pro-inflammatory factors, and display outstanding cytotoxic effects against cancer cells in vitro. In summary, this bioengineering strategy displayed a broader prospect for photothermal-immunotherapy synergy.

Construction of Cd8.05Zn1.95S10/CdZn19S20 heterostructure with the same elements and its photocatalytic performance

Constructing heterostructure photocatalyst with intimate contact is an effective strategy to improve the photocatalytic property. Herein, we constructed a novel heterostructure consisting of the same elements via a two-step hydrothermal process. The obtained Cd8.05Zn1.95S10/CdZn19S20 heterostructure exhibited enhanced photocatalytic activity, whose H2 generation rate (6.16 mmol/h/g) was 3.2 and 2.6 times higher than that of CdZn19S20 (1.92 mmol/h/g) and Cd8.05Zn1.95S10 (2.33 mmol/h/g), respectively. In addition, Cd8.05Zn1.95S10/CdZn19S20 also presented excellent photocatalytic activity for methyl orange (MO) degradation, which could remove 95.5 % of MO within 60 min of visible light irradiation. The efficient separation and transfer of photogenerated charge carriers were the main reasons for the enhanced photocatalytic activity, which was confirmed by photoluminescence spectra (PL), transient photocurrent response and electrochemical impedance (EIS). And meanwhile, the possible photocatalytic H2 production mechanism of Cd8.05Zn1.95S10/CdZn19S20 heterostructure was proposed. This work may provide a reference and foundation to design similar heterostructure photocatalysts.

Flower-like layered ZnO nanoflakes for cost-effective visible light-assisted photodynamic oxidation of tetracycline and bacterial disinfection

The conventional precipitation method was employed to synthesize the flower-like layered ZnO nano-flakes, characterized, and their photocatalytic potential was investigated for control of tetracycline antibiotics and high-strength pathogenic bacteria in wastewater effluent. Scanning electron microscope measurements confirm the formation of flower-like nano-flakes. Under white light, the catalytic efficiency of the ZnO nano-flakes is higher compared to blue light for the photocatalytic degradation of tetracycline, the inactivation of multidrug-resistant bacteria, and total coliforms. Under white light irradiation with the intensity of 80 mW/cm2, the ZnO nano-flakes showed the highest tetracycline degradation efficacy of 86 % within 120 min and complete inactivation of bacteria within 90 min without any additional oxygen sources. Scavenging experiments have clarified the photocatalytic mechanism of the degradation of tetracycline. The used catalyst was simply recovered by centrifugation (5 min) and could be reused without significant loss of photocatalytic activity. The remarkable efficiency and stability of the ZnO nano-flakes in this study mark a distinct approach to the development of heterogeneous photocatalysts for pollutant degradation. To evaluate the feasibility of a photocatalytic process for achieving consistent disinfection, microbial inactivation experiments were conducted using a batch-scale photocatalytic reactor with blue and white LEDs. The study targeted high-strength multidrug-resistant bacteria, including E. coli (Gram-negative) and S. aureus (Gram-positive), as well as total coliform in secondary effluent. This research clarifies the practical potential of ZnO nano-flakes for cost-effective photocatalytic oxidation treatment of wastewater pollutants.

Cobalt coordinated olefin-linked covalent organic frameworks toward highly efficient photocatalytic hydrogen production

Covalent organic frameworks (COFs) have emerged as a crystalline porous materials for photocatalytic hydrogen production. However, the design of efficient COF-based catalyst for satisfactory solar-to-hydrogen energy conversion is still challenging. Here, cobalt was anchored on the bipyridine moieties in the framework of olefin-linked sp2c-COFdpy by convenient post-metalation (sp2c-COFdpy-Co). Experimental results showed that sp2c-COFdpy-Co exhibited wider visible light absorption region and quicker photogenerated e-/h+ separation efficiency than sp2c-COFdpy. Photocatalytic experiments revealed that sp2c-COFdpy-Co was highly efficient for H2 production after photodeposition of Pt co-catalyst (Pt@sp2c-COFdpy-Co). The optimized Pt@sp2c-COFdpy-Co exhibited a high photocatalytic H2 production rate of 324.4 μmol/h under visible light irradiation in the presence of 1.0 wt% Pt as co-catalyst, which was higher than Pt@sp2c-COFdpy-Fe and Pt@sp2c-COFdpy-Ni, and it was much higher than that of its counterparts and many reported works. This work provides new insights into design of highly efficient COF-based catalyst for photocatalytic H2 production.

A novel 0D/2D Z-scheme heterojunction Bi2Sn2O7/Bi4O7 for boosting tetracycline photodegradation: Insight from performance to mechanism

The slow migration and low separation efficiency of charge carriers inhibit the photocatalytic degradation of pollutants in water. Constructing heterojunction is an effective strategy to enhance photocatalytic performance. Herein, a novel Z-scheme Bi2Sn2O7/Bi4O7 (BOBSO) heterojunction was designed and synthesized for degrading typical antibiotics in water. The 0.2BOBSO heterojunction exhibits excellent photocatalytic performance, achieving a 97.97 % tetracycline degradation rate under visible light irradiation, significantly surpassing the individual materials Bi2Sn2O7 (75.93 %) and Bi4O7 (18.61 %). The composite photocatalyst shows excellent stability and strong adaptability to environmental factors. Compared to Bi2Sn2O7 and Bi4O7, 0.2BOBSO heterojunction possesses superior microstructure and photoelectrochemical properties confirmed by various characterizations. The electron transfer mechanism of Z-scheme heterojunction on the composite surface was proposed according to in-depth analyses using UV–vis, Mott-Schottky, and Electron Spin Resonance (ESR). The formation of Z-scheme heterojunction accelerates the migration of photogenerated charge carriers while maintaining the optimal redox ability of the materials. Furthermore, quenching experiments confirm that h+, O2−, and 1O2 are the main active species in the reaction system, with TC degraded via both radical and non-radical pathways. This study provides new insights into the design and construction of 0D/2D Z-scheme heterojunction photocatalysts.