Visible LED Light Irradiation Research Articles

Sintering Driven Void Formation in PS@WO3 Core-Shell Composites: A Photodegradation Enhancement Strategy

Background: Polystyrene nanospheres are used as a substrate for the hydrothermal coating of tungsten trioxide (WO3) to form a core-shell composite of PS@WO3. The core-shell structure is used for the next sintering step. This produces porous WO3. The focus of this study is on the role of porous WO3 in enhancing photocatalytic performance. Methods: The hydrothermal method was employed for coating, and the surface morphology, as well as the structural properties of WO3-coated PS spheres, were systematically investigated using SEM and XRD analyses. Additionally, the sintering process was introduced to enhance the material by inducing rupture in the PS sphere core, creating voids that significantly increased the material's surface area. Results: The evaluation of the effect of sintering temperature on photodegradation efficiency highlighted the crucial role of sintering temperature. Un-sintered and 300°C sintered WO3, both having a hexagonal crystalline structure, exhibited superior degradation efficiencies compared to samples sintered at higher temperatures (400°C and 500°C). In particular, the 300°C sintered WO3 outperformed its un-sintered counterpart despite identical crystalline structures. The performance of the PS@WO3 composite was assessed to determine the enhanced role of porous WO3. The porous WO3 obtained, in particular by the sintering of the core-shell PS@WO3 composites at 300°C, showed a remarkable improvement in the degradation efficiency. These composite demonstrated over 95% efficiency within 10 minutes and achieved near complete (100%) degradation for a further 10 minutes, surpassing the performance of pure WO3. It is important to clarify that while the final product was predominantly WO3 after the sintering process, the inclusion of PS served a critical purpose in creating voids during sintering. The PS@WO3 composite structure used as a resource for the preparation of porous WO3, even with a potentially reduced PS composition, has been found to play a significant role in influencing the surface area of the material, and consequently the photocatalytic performance. Conclusion: The study has highlighted the importance of crystalline structure and sintering conditions in optimizing the efficiency of photocatalytic materials. The porous WO3 obtained, in particular by the sintering of the core-shell PS@WO3 composites at 300°C, showed promising potential for applications under UV and visible LED light irradiation. These results provide valuable insights for the development of advanced photocatalytic materials with improved performance, highlighting WO3 as the key contributor to the observed improvements.

BiVO4/sulfur-doped g-C3N4 nanocomposite as photocatalyst for degradation of ciprofloxacin under visible light irradiation

In recent years, the use of antibiotics has greatly increased, which has caused environmental pollution. We offer a photocatalyst based on BiVO4/sulfur-doped g-C3N4 nanocomposite, which was made by a one-step thermal condensation method from thiourea and bismuth vanadate to degradate ciprofloxacin (CIP). The BiVO4/sulfur-doped g-C3N4 photocatalyst was analyzed by certain techniques including XRD, FTIR, BET, FESEM, EDX, TEM, DRS, photoluminesence, and Mott-Schottky to determine various physicochemical properties. The photocatalytic degradation of CIP, as a model pollutant, under visible LED light irradiation was tested to investigate the catalytic performance of nanocomposite. Response Surface Methodology (RSM) was employed to optimize operational parameters, including photocatalyst dosage (50–150 mg), CIP concentration (10–30 mg/L), initial pH of the solution (3–11), and irradiation time (12–120 min). The BiVO4/sulfur-doped g-C3N4 nanocomposite, with a narrow bandgap of 2.15 eV, exhibited exceptional photocatalytic performance in degrading CIP. The optimal conditions for CIP removal were photocatalyst dosage of 120.9 mg, CIP concentration of 10 mg/L, and initial solution pH of 3, resulting in 93.5 % removal efficiency after 105 min of irradiation. The photocatalytic degradation kinetics of CIP followed a pseudo-first-order model with a rate constant (K) of −0.0221 L/min, indicating rapid degradation process. The photocatalyst maintained excellent performance after 5 reuses, with only a 3 % reduction in efficiency. XRD analysis confirmed the structural stability of the nanocomposite after reuse.

Unraveling the antimicrobial activity of CuS functionalized titanates under visible LED light irradiation

Titanate nanotubes (TNs) functionalized with CuS nanoparticles using the microwave-assisted hydrothermal method were characterized via XRD, Raman spectroscopy, UV–Vis spectrophotometry, and N2 physisorption. The as-synthesized CuS/TNs had anatase as the main crystalline phase and the band-gap energy was in the visible region, 2.9 eV. The TNs were recrystallized on titania and functionalized with CuS, forming spherical bundles. SEM showed agglomerates of cauliflower-like semispherical particles. The antimicrobial photoactive assets were evaluated against the bacteria Staphylococcus aureus and Escherichia coli. Inhibition was clearly visible in S. aureus after the first 20 min of exposure to a 6-W LED irradiation lamp. The visible-light catalyzed completely and irreversibly the inactivation of S. aureus after 60 min, however, in the case of E. coli, this material only slightly disturbed its growth, which was recovered after 60 min. The successful result obtained with S. aureus can be explained by the fact that it lacks periplasmic superoxide dismutase (SOD) but has staphyloxanthin for external protection against ROS. However, the CuS/TN particles could release Cu2+ ions, which got attached to bacterium structures or entered the cytoplasm; these events together with the generation of ROS under visible LED light helped inactivate quickly staphyloxanthin, thus inflicting permanent damage to the periplasmic membrane.

Nitrogen-Rich Triazine-Based Covalent Organic Frameworks as Efficient Visible Light Photocatalysts for Hydrogen Peroxide Production.

Covalent organic frameworks (COFs) have been widely used in photocatalytic hydrogen peroxide (H2O2) production due to their favorable band structure and excellent light absorption. Due to the rapid recombination rate of charge carriers, however, their applications are mainly restricted. This study presents the design and development of two highly conjugated triazine-based COFs (TBP-COF and TTP-COF) and evaluates their photocatalytic H2O2 production performance. The nitrogen-rich structures and high degrees of conjugation of TBP-COF and TTP-COF facilitate improved light absorption, promote O2 adsorption, enhance their redox power, and enable the efficient separation and transfer of photogenerated charge carriers. There is thus an increase in the photocatalytic activity for the production of H2O2. When exposed to 10 W LED visible light irradiation at a wavelength of 420 nm, the pyridine-based TTP-COF produced 4244 μmol h-1 g-1 of H2O2 from pure water in the absence of a sacrificial agent. Compared to TBP-COF (1882 μmol h-1 g-1), which has a similar structure but lacks pyridine sites, TTP-COF demonstrated nearly 2.5 times greater efficiency. Furthermore, it exhibited superior performance compared to most previously published nonmetal COF-based photocatalysts.

K doped defective g-C3N4 decorated with cyano group for boosting visible-light driven photocatalytic removal of uranium

Utilizing elemental doping and defect engineering are effective means to enhance the efficiency of g-C3N4 materials for photocatalytic removal of uranium. In this investigation, we synthesized a defective g-C3N4 photocatalyst co-decorated with K+ doping and cyano groups (KHCN) through a straightforward one-step alkali etching process. The alkali etching not only enhances the specific surface area to improve the adsorption of uranium by KHCN but also significantly accelerates the photocatalytic removal of uranium through the introduction of K+ and cyano groups. The KHCN can almost completely remove 40 mg/L of U(VI) under air and visible LED light irradiation (pH 5.0, 298.15 K). Notably, the photocatalytic removal of U(VI) by KHCN demonstrated excellent selectivity and reusability. The mechanism studies reveal that alkali etching-induced introduction of K+ ions and cyano groups enhances visible light absorption, strengthens the efficiency of photogenerated carrier separation, and reduces the band gap. The activation of U(VI) in solution primarily occurs through photogenerated e- and O2–, subsequently immobilizing as metastudtite ((UO2)O2·2H2O). This study provides a viable approach for synthesizing highly efficient photocatalytic materials for uranium removal, leveraging synergistic doping and defect engineering.

Visible light active Ti3+ self-doped mesoporous TiO2 photocatalyst with efficient photocatalytic performance for the degradation of chlorpyrifos

ABSTRACT In the present research, Ti3+ self-doped TiO2 photocatalyst (Ti3+-TiO2) was fabricated through a facial in-situ NaBH4 reduction approach. The as-prepared Ti3+-TiO2 were characterised using FESEM-EDS, TEM, HRTEM, XRD, UV-DRS, PL, EIS, and BET methods. The photocatalytic performance of the Ti3+-TiO2 was assessed through the degradation of chlorpyrifos (CPY) as an organophosphorus pesticide under visible LED light irradiation. The Ti3+-TiO2 exhibited excellent photocatalytic degradation efficiency at initial CIP concentration = 1 mg L−1, pH = 7, catalyst dosage = 0.2 g L−1, and reaction time of 50 min with 97%, which is 4.62 times higher than that of pristine TiO2. The extraordinarily boosted photocatalytic activity of Ti3+-TiO2 can be attributed to mesoporous nanostructure, oxygen vacancy, and Ti3+ self-doping, which facilitates visible light harvesting and accelerates charge carrier separation and transport. In addition, Ti3+-TiO2 shows outstanding mineralisation capability and recycling performance in degrading CPY. Coexisting water anions (NO3 −, Cl−, SO4 2-, HCO3 −) and HA inhibited the degradation of CPY. Their inhibition effects of selected anions followed the order of HCO3 − > SO4 2-> NO3 − > Cl−. Besides, a possible reaction mechanism of the photocatalytic process was recommended based on evidence from the radical scavenging test and photoelectrochemical measurements. The energy consumption value in this study was much less than that reported in other studies. Collectively, the findings show that Ti3+-TiO2 photocatalyst has tremendous potential in solar photocatalytic degradation of refractory organic pollutants.

Hydrothermal Synthesis of Heterostructured g-C3N4/Ag-TiO2 Nanocomposites for Enhanced Photocatalytic Degradation of Organic Pollutants.

In this study, heterostructured g-C3N4/Ag-TiO2 nanocomposites were successfully fabricated using an easily accessible hydrothermal route. Various analytical tools were employed to investigate the surface morphology, crystal structure, specific surface area, and optical properties of as-synthesized samples. XRD and TEM characterization results provided evidence of the successful fabrication of the ternary g-C3N4/Ag-TiO2 heterostructured nanocomposite. The heterostructured g-C3N4/Ag-TiO2 nanocomposite exhibited the best degradation efficiency of 98.04% against rhodamine B (RhB) within 180 min under visible LED light irradiation. The g-C3N4/Ag-TiO2 nanocomposite exhibited an apparent reaction rate constant 13.16, 4.7, and 1.33 times higher than that of TiO2, Ag-TiO2, and g-C3N4, respectively. The g-C3N4/Ag-TiO2 ternary composite demonstrated higher photocatalytic activity than pristine TiO2 and binary Ag-TiO2 photocatalysts for the degradation of RhB under visible LED light irradiation. The improved photocatalytic performance of the g-C3N4/Ag-TiO2 nanocomposite can be attributed to the formation of an excellent heterostructure between TiO2 and g-C3N4 as well as the incorporation of Ag nanoparticles, which promoted efficient charge carrier separation and transfer and suppressed the rate of recombination. Therefore, this study presents the development of heterostructured g-C3N4/Ag-TiO2 nanocomposites that exhibit excellent photocatalytic performance for the efficient degradation of harmful organic pollutants in wastewater, making them promising candidates for environmental remediation.

Design and Synthesis of NTU-9/C3N4 Photocatalysts: Effects of NTU-9 Content and Composite Preparation Method.

Hybrid materials based on graphitic carbon nitride (g-C3N4) and NTU-9 metal-organic frameworks (MOF) were designed and prepared via solvothermal synthesis and calcination in air. The as-prepared photocatalysts were subsequently characterized using Brunauer-Emmett-Teller (BET) analysis, UV-Vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) emission spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The obtained NTU-9/C3N4 composites showed a greatly improved photocatalytic performance for the degradation of toluene in the gas phase under LED visible-light irradiation (λmax = 415 nm). The physicochemical properties and photocatalytic activities of the obtained NTU-9/C3N4 materials were tuned by varying the NTU-9 content (5-15 wt%) and preparation method of the composite materials. For composites prepared by calcination, the photocatalytic activity increased with decreasing NTU-9 content as a result of the formation of TiO2 from the MOFs. The best photocatalytic performance (65% of toluene was photodegraded after 60 min) was achieved by the NTU-9/C3N4 sample prepared via the solvothermal method and containing 15 wt% MOF, which can be attributed to the appropriate amount and stable combination of composite components, efficient charge separation, and enhanced visible-light absorption ability. The photocatalytic mechanisms of the prepared hybrid materials depending on the preparation method are also discussed.

G-C3N4 supported Ag/AgCl@MIL-88A MOF based triple composites for highly efficient diuron photodegradation under visible LED light irradiation

In this work, a series of g-C3N4 supported Ag/AgCl doped MIL-88A composites were synthesized and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), UV–vis diffuse reflectance spectroscopy (UV–vis DRS), and photoluminescence spectroscopy (PL). The photocatalytic performances of as-prepared composites were examined by the photodegradation of diuron (DRN), which is used as an herbicide in agriculture. The composites exhibit exceptional visible-light photocatalytic activities for photodegradation of DRN with complete degradation within 60 min in the absence of oxidants. However, in the presence of H2O2 or persulfate, complete degradation of DRN was achieved in 15 min and 30 min, respectively. The photocatalyst also gave very high conversions in water containing dissolved inorganic salts and natural organic matter (NOM). The Ag/AgCl@MIL-88A/g-C3N4 composite retained excellent photocatalytic properties after repeated use. Radical trapping experiments revealed that the most important reactive species in the photodegradation were O2−• and h+. Role of active radicals were discussed via proposed degradation mechanism for the degradation of DRN in the presence of MIL-88A/g-C3N4 and Ag/AgCl@MIL-88A/g-C3N4.

MnOx-decorated oxygen-doped g-C3N4 with enhanced photocatalytic activity for efficient removal of uranium(VI)

Photocatalysis can convert soluble hexavalent uranium (U(VI)) to insoluble tetravalent uranium (U(IV)), which can then be removed and recovered from water, making it a promising method for treating uranium-containing wastewater. In this study, we developed a novel MnOx-decorated oxygen-doped g-C3N4 (OCNM) photocatalyst for efficient photocatalytic extraction of uranium from uranium-containing wastewater. The oxygen doping and surface-decorated MnOx can synergistic promote the response of visible light and separation and transfer efficiency of photogenerated carriers, resulting in excellent performance of OCNM for photocatalytic extraction of uranium. Under aerobic and visible LED light irradiation, the as-synthesized OCNM can almost completely remove U(VI) in uranium solution with a concentration range of 1–100 mg/L at pH 5.0. The removal rate of U(VI) by OCNM remained (91.8%) after 5 consecutive adsorption–desorption cycles tests, indicating that this material is highly recyclable. Furthermore, the OCNM exhibits high selectivity for U(VI) in coexisting metal ion solutions. Further mechanism study revealed that the photogenerated e- and ·O2– play an important role in U(VI) removal, with the U(VI) being immobilized as schoepite ((UO2)8O2(OH)12·12H2O) by OCNM during the photocatalytic reaction. This study presents a promising material and approach for the effective treatment of uranium wastewater using photocatalytic technology.

Design of few-layer carbon nitride/BiFeO3 composites for efficient organic pollutant photodegradation

Heterojunction-driven photocatalysis can degrade various organic pollutants, and developing carbon nitride-based composite photocatalysts is of great significance and gains growing interest. In this study, a two-dimensional graphitic carbon nitride nanosheets/BiFeO3 (GCNNs/BiFeO3) Z-scheme heterojunction has been synthesized through the electrostatic spinning and post-calcination The obtained GCNNs/BiFeO3 nanofibers show large surface contact between GCNNs the and BiFeO3 nanostructures. The Z-scheme heterojunction shows a remarkably enhanced photocatalytic performance, which could degrade 94% of tetracycline (TC) and 88% of Rhodamine B (RhB) under LED visible light irradiation in 150 min. Radical trapping experiments demonstrate the effective construction of Z-scheme heterojunctions, and •O2− and h+ are the main active species in the photocatalytic degradation process. This study realizes a novel nanostructured GCNNs/BiFeO3 heterojunction for photodegradation applications, which would guide the design of next-generation efficient photocatalysts.

Nanoarchitecture of graphene nanosheets decorated with NiCr layered double hydroxide for sonophotocatalytic degradation of refractory antibiotics

Highly efficient and durable catalysts for wastewater treatment are urgently required to tackle critical environmental issues. In this regard, NiCr LDH (NC), NiCr LDH-GO (NC-GO), and NiCr LDH-rGO (NC-rGO) nanocomposites were synthesized. The results of XRD, EDX, and FTIR analyses not only explored the crystallographic and chemical structures of catalysts but also confirmed the successful synthesis. Further morphological, physical, chemical, and optical characteristics of the catalysts were evaluated more by SEM, HRTEM, BET, DRS, and XPS techniques. The as-synthesized catalysts were used for the efficient mineralization of rifadin under 50 W LED visible light irradiation and the ultrasonic power of 150 W. Amongst, 0.75 g L−1 of NC-rGO demonstrated high sonophotocatalytic efficiency (88%) in natural pH (pH = 8) of 15 mg L−1 of rifadin. The introduced system is also powerful for the decontamination of pharmaceutical-containing wastewater as well as other refractory antibiotics. Moreover, the radical trapping experiments demonstrated that the main reactive species involved in the degradation of rifadin are •OH, h+, and O2•–. The possible intermediates were thoroughly investigated using GCMS analysis. Also, NC-rGO demonstrated superior antibacterial activity in comparison with NC, NC-GO samples.

Efficient visible-light-driven photoreduction of U(VI) by carbon dots modified porous g-C3N4

The efficient removal of uranium from radioactive wastewater is of great significance for the ecological environment safety and sustainable development of nuclear energy. Herein, the carbon dots modified porous graphitic carbon nitride (CNCD) was fabricated and used for photoreduction of U(VI) under visible LED light irradiation. The removal rate of U(VI) by CNCD-2 could reach more than 95 % over a wide range of U(VI) concentration. In addition, the CNCD-2 showed excellent selectivity and recyclability for photoreduction of U(VI). Further mechanism studies showed that the high photocatalysis activity of CNCD-2 was attributed to the effective separation of photoinduced electron-hole pairs, strong visible light absorption capacity and narrow bandgap. The U(VI) was activated by both photoinduced e- and •O2– in the process of photoreduction, and then immobilized by transforming it to metastudtite ((UO2)O2·2H2O). These results indicate that the CNCD is a promising material for remediation of uranium-containing wastewater under visible light irradiation.

Photocatalytic membrane of TiO2/CNT decorated PAN nanofibers with enhanced performance under LED visible-light irradiation

Incorporating TiO2 with CNTs and PAN nanofiber structures results in a photocatalytic membrane composite with an attractive response in the visible region. It offers an efficient process without post-treatment separation at the end of the photocatalytic treatment. The composite membranes were fabricated using electrospinning at 7 kV with 10 cm in the distance between needle tip and collector at a flow rate of 1 mL h−1. Polyacrylonitrile (PAN) was used as the polymer matrix. All the as-spun composites exhibited randomly oriented nanofibers. CNT increased the fiber diameters from 324 to 463 nm. The bandgap of TiO2 also shifted from 3.15 to 2.76 eV at the narrowest The color removal kinetics follow the Langmuir-Hinshelwood pseudo-first-order kinetics model with the highest rate constant of 0.0225 min−1 shown by PAN/TiO2/CNT 20%. More than 95% color removal of methylene blue after 100 min irradiation has been achieved using LED lamps of low energy visible light (43.5 W). Such a result is supposed to be the highest employing low energy lamps. [Formula: see text]

Facile synthesis of magnetic ZnFe2O4/AC composite to activate peroxydisulfate for dye degradation under visible light irradiation.

Heterogeneous photocatalysis/persulfate oxidation process has been considered as a promising technology for dye contaminants removal. The magnetic ZnFe2O4/active carbon (AC) composites were hydrothermally synthesized and firstly used to activate peroxydisulfate (PDS) for rhodamine B (RhB) degradation under visible LED light irradiation. The optimized Vis-ZnFe2O4/AC(4/1)-PDS system can enhance the RhB degradation efficiency by 32.01% and 13.87% compared with Vis-ZnFe2O4-PDS and Vis-AC-PDS systems, respectively. The influence of operational parameters such as catalyst dosage (0.2 - 0.4g L-1), PDS concentration (1.0 - 2.0g L-1), temperature (25 - 45°C), solution pH (2.7 - 10.9), and coexisting inorganic ions (Cl-, NO3-, HCO3-, PO43-, Cu2+, Fe3+, and Ca2+) on RhB degradation was studied, and 100% of RhB (20mg L-1) was degraded after 80min at operational condition: 0.30g L-1 of ZnFe2O4/AC(4/1) and 1.5g L-1 of PDS, solution pH of 2.74, reaction temperature of 25°C. The quenching experiments, EPR test, and XPS analysis were employed to reveal the proposed mechanism, which demonstrated that 1O2 played a more important role than other reactive species (SO4•-, •OH, O2•-, and h+) in RhB degradation. The generation of 1O2 via the two routes was as follows: (i) the in situ formed active oxygen (O*) reacted with HSO5- to produce 1O2; (ii) O2•- was oxidized by h+ to form 1O2. After five consecutive cycles, the photodegradation efficiency of RhB by ZnFe2O4/AC(4/1) catalyst slightly decreased from 88.52 to 83.92%, indicating the excellent reusability of ZnFe2O4/AC(4/1) photocatalyst. As designed, Vis-ZnFe2O4/AC-PDS oxidation system can effectively remove RhB from the different real water matrices, and the degradation efficiency of RhB in tap water, river water, and secondary effluent was 78.24%, 79.55%, and 74.53% after 80min of reaction, respectively.

Porphyrin Catecholate Iron-Based Metal–Organic Framework for Efficient Visible Light-Promoted One-Pot Tandem C–C Couplings

Introduction of metal–organic frameworks (MOFs) beyond metal-carboxylate series and their applications are still challenging. An innovative porous porphyrin catecholate iron-based MOF (PorphCat-Fe) with a Brunauer–Emmett–Teller (BET) surface area of 700 m2 g–1 has been designed and synthesized through solvothermal self-assembling porphyrin catecholate linkers and iron(II) chloride as a cheap and earth-abundant node precursor. The structure was then evaluated with various techniques and utilized as an efficient and stable heterogeneous material for domino one-pot selective benzyl alcohol oxidation/Knoevenagel condensation reaction under visible LED light irradiation. The photocatalytic performance was remarkably improved as compared to individual components, affording excellent product yields (91%) with almost quantitative transformation of benzyl alcohol. The combination of Fe(III)-Lewis acidic sites and free-base porphyrin photosensitizers within the porous solid material make PorphCat-Fe able to show superior catalytic activity for this transformation. In addition, the MOF can easily accommodate the starting materials inside its mesopores and, thereby, make them easily accessible to active sites. This is an unusual example of an all-in-one noble metal-free bio-inspired supramolecular chemistry for an advanced organic transformation without the need of any chemical additive or further structural modification using only visible LED light conservation.

Fabrication of g-C3N4/Sn3O4/Ni electrode for highly efficient photoelectrocatalytic reduction of U(VI)

• g-C 3 N 4 /Sn 3 O 4 /Ni (CSN) electrode was constructed by simple hydrothermal method. • U(VI) can be effectively removed by CSN electrode via photoelectrocatalytic method. • High photoelectric activity of CSN electrode is dependent on its strong optical adsorption ability and narrow band gap. • CSN electrode has good recyclability and high selectivity. Removal of uranium from uranium-containing wastewater is of great significance for uranium contamination remediation and development of nuclear energy. In this paper, the g-C 3 N 4 /Sn 3 O 4 /Ni (CSN) electrode was fabricated and used as photoanode for photoelectrocatalytic reduction of U(VI) under visible LED light irradiation, and a photoelectrocatalytic approach was proposed to efficiently remove uranium from uranium-containing wastewater. The U(VI) was deposited as U(IV) at cathode and the removal rate of U(VI) reached 94.28 % at pH of 5.0 for photoelectrocatalytic approach, while the removal rates of U(VI) only amounted to 10.56 % and 36.65 % for the photocatalytic and electrochemical extraction approaches, respectively. Furthermore, the photoelectrocatalytic reduction mechanism for U(VI) is explored by XPS, EIS, PL, EPR and DFT calculations, which indicated that the excellent photoelectrocatalytic performance of CSN electrode for U(VI) is mainly because it enhanced visible light absorption, promoted separation of photogenerated electron-hole pairs and decreased the band gap. This work provided a facile route for efficient removal of U(VI) from uranium-containing wastewater via photoelectrocatalytic method.

Hydrochar-mediated photocatalyst Fe3O4/BiOBr@HC for highly efficient carbamazepine degradation under visible LED light irradiation

• Hydrochar-mediated Fe 3 O 4 /BiOBr@HC was synthesized by a hydrolysis method. • Efficient carbamazepine removal benefited from synergistic effect of Fe 3 O 4 and HC. • Faster charge separation and more active species generation occurred with help of HC. • Active species include superoxide radicals, hydroxyl radicals, and photogenerated holes. • Three degradation pathways were proposed to indirectly verify the role of active species. Construction of composite photocatalysts with high charge transfer efficiency and fast surface catalytic reaction has recently gained huge interest. In this work, a hydrochar microsphere-mediated photocatalyst Fe 3 O 4 /BiOBr@HC with rapid surface catalytic reaction and electron transfer was fabricated. Under visible-LED-light irradiation, removal of refractory analgesic carbamazepine (CBZ) and total organic carbon (TOC) reached 100% and 67.41%, respectively, by Fe 3 O 4 /BiOBr@HC20% within 40 min, demonstrating the excellent photocatalytic activity compared to other photocatalysts. The narrower band gap (2.02 eV) of Fe 3 O 4 /BiOBr@HC obviously improved the visible light absorption. The hydrochar with abundant surface oxygen functional groups provided more active oxygen species ·O 2 – (4.05 µM) and ·OH (107.8 nM), and acted as an electron bridge to promote the electron transfer of BiOBr and Fe 3 O 4 . Eleven main CBZ intermediates were identified and three degradation pathways were proposed to illustrate the contribution of superoxide radicals, hydroxyl radicals, and photogenerated holes to the photodegradation of CBZ. Furthermore, five-cycle reusing experiments revealed that Fe 3 O 4 /BiOBr@HC composite catalysts have excellent reusability and stability, indicating that they have a promising application future.

Photocatalysis of TiO2 Sensitized with Graphitic Carbon Nitride and Electrodeposited Aryl Diazonium on Screen-Printed Electrodes to Detect Prostate Specific Antigen under Visible Light.

We report on a photoelectrochemical (PEC) device to detect prostatic-specific antigen (PSA) under visible LED light irradiation within the point-of-care (POC) paradigm. The device consists of a 3D printed miniaturized photoelectrochemical system and a disposable PEC immunosensor made with screen-printed carbon electrodes (SPCEs). The SPCEs were coated with nickel single atoms anchored on graphitic carbon nitride (Ni-gC3N4), titanium dioxide nanoparticles (TiO2), and aryl diazonium salt prepared from p-aminobenzoic acid. The electrodeposited aryl diazonium on Ni-gC3N4/TiO2 decreased the recombination of photogenerated charge carriers, leading to a 3.1-fold increase in the photocurrent compared to pure TiO2. This functionalization strategy provides carboxylic groups to anchor antibodies via the carbodiimide reaction, which may be extended to any other type of immunosensor. Under optimal conditions, the PEC immunosensor was able to detect PSA from 10-16 to 10-8 g mL-1 with a detection limit of 0.06 fg mL-1. The device robustness was confirmed with reproducibility and stability tests. PSA could also be detected in human serum samples, which demonstrates the potential of the PEC immunosensor for clinical diagnosis.

Synthesis of novel α-Fe2O3-Bi2S3-Gr for efficient photocatalytic degradation of environmental pollutants under visible-LED light irradiation

• Successful synthesis of α-Fe 2 O 3 -Bi 2 S 3 -Gr by a facile hydrothermal method. • Visible-LED light was chosen as the light source for benzotriazole degradation. • ● OH radical acts as the main reactive specie during photocatalytic reactions. • A mechanism for benzotriazole degradation over the catalyst is proposed. • The catalyst has a superior activity and exhibits good stability over four cycles. α-Fe 2 O 3 -Bi 2 S 3 nanorods was successfully synthesized via a hydrothermal route with incorporation of graphene obtained from the pyrolysis of alginate, and was employed as a catalyst of the degradation of benzotriazole (BTA) in a photo-Fenton process. Due to the unique combination of graphene and the binary α-Fe 2 O 3 -Bi 2 S 3 nanorod, the sample with 3 wt% graphene loading shows a high catalytic activity of 98% of BTA conversion under LED-visible light. The quenched free radicals are detected with an Electron Spin Resonance (ESR) technique, and the results indicate that hydroxyl radical • OH contributed to the BTA degradation reaction. A mechanism is proposed. Furthermore, the reusability of the catalyst was examined and the catalyst showed high activity over four cyclic runs.