Radical Capture Research Articles

Synergistic optimization of triple phase junctions and oxygen vacancies over MnxCd1-xS/Ov-WO3 for boosting photocatalytic hydrogen evolution.

Strengthening the separation of photogenerated charge carriers is crucial for improving the efficiency of photocatalytic hydrogen evolution. Herein, t-Mn0.5Cd0.5S/Ov-WO3 (t-MCSW) triple-phase junctions with rich oxygen vacancies were developed using the calcination-hydrothermal method. The corresponding morphology and structure of the samples were examined by XRD, TEM and XPS. The formation of the S-scheme heterostructure in t-MCSW has also been confirmed with in situ XPS, work function analysis and free radical capture tests. The experimental results demonstrate that t-MCSW-7 exhibited optimal activity (194.2 mmol g-1 h-1), which was about 4 times higher than that of the individual Mn0.5Cd0.5S (t-MCS, 48.8 mmol g-1 h-1). The apparent quantum yield of t-MCSW-7 is 29.14% at 420 nm, and the material exhibits excellent stability after seven cycles of photocatalytic reaction. The excellent photocatalytic activity of t-MCSW-7 is attributed to more efficient separation of charge carriers by triple-phase junctions connected by homojunctions and heterojunctions. Moreover, the existence of oxygen vacancies broadens absorption spectra and accelerates surface charge transfer. The synergistic effect of phase junctions and oxygen vacancies leads to an enhancement of hydrogen evolution activity. This work provides a new idea for preparing efficient photocatalysts.

Electrochemical-induced solvent-tuned selective C(sp3)-H bond activation towards the synthesis of C3-functionalized chromone derivatives.

An unprecedented solvent-tuned electrochemical method for selective C(sp3)-H bond activation towards the synthesis of C3 functionalized chromone derivatives has been developed. This electrosynthesis protocol provides an efficient and green way to access various C3-functionalized chromones by avoiding traditionally employed transition metals and high temperatures. The swappable chemoselectivity was controlled mainly by altering the solvent and the current. A plausible reaction mechanism has been proposed with the help of radical capture and cyclic voltammetry experiments.

Copper catalyzed benzylic sp3 C-H alkenylation.

The prenyl group is present in numerous biologically active small molecule drugs and natural products. We introduce benzylic C-H alkenylation of substrates Ar-CH3 with alkenylboronic esters (CH2)3O2B-CH[double bond, length as m-dash]CMe2 as a pathway to form prenyl functionalized arenes Ar-CH2CH[double bond, length as m-dash]CMe2. Mechanistic studies of this radical relay catalytic protocol reveal diverse reactivity pathways exhibited by the copper(ii) alkenyl intermediate [CuII]-CH[double bond, length as m-dash]CMe2 that involve radical capture, bimolecular C-C bond formation, and hydrogen atom transfer (HAT).

An oxygen vacancy-rich BiO2-x/COF heterojunction for photocatalytic degradation of diclofenac.

A BiO2-x/COF composite was successfully synthesized by simple mechanical ball milling. Compared to pure BiO2-x and COFs, the BiO2-x/COF composite (1 : 9) showed superior photocatalytic capability. Under visible light irradiation for 90 min, the photocatalytic degradation rate of DCF reached 97%. In addition, the characterization results showed that the formation of heterojunctions and the increase in oxygen vacancy concentration were the reasons for the enhancement of the photocatalytic activity. It is confirmed by free radical capture experiments that ˙O2- and h+ are the main reactive substances in the photocatalytic process. The photocatalytic degradation mechanism of the composite and the photocatalytic degradation pathway of diclofenac were deduced.

CdS QDs grown on ellipsoidal BiVO4 for efficient photocatalytic degradation of tetracycline.

Designing efficient, inexpensive, and stable photocatalysts to degrade organic pollutants and antibiotics has become an effective way for environmental remediation. In this work, we successfully performed in situ growth of CdS QDs on the surface of elliptical BiVO4 to try to show the advantage of the binary heterojuncted photocatalyst (BVO@CdS) for the photocatalytic degradation of tetracycline (TC). The In situ growth of CdS QDs can provide a large number of reactive sites and also generate a larger contact area with BiVO4. In addition, compared with mechanical composite materials, in situ growth can significantly reduce the energy barrier at the interface between BiVO4 and CdS, providing more channels for the separation and migration of photogenerated charge carriers, and further improving reaction activity. As a result, BVO@CdS-0.05 shows the best degradation efficiency, with a degradation rate of 88% after 30 min under visible light. The TC photodegradation follows a pseudo-second-order reaction with a dynamic constant of 0.472 min-1, which is 6.47 times that of pure BiVO4, 7.24 times that of pure CdS QDs and 2 times that of the mechanical composite. The degradation rate of BVO@CdS-0.05 decreases to 77.8% with a retention rate of 88.5% after four cycles, demonstrating excellent stability. Through liquid chromatography-mass spectrometry (LC-MS) analysis, two possible pathways for TC degradation are proposed. Through free radical capture experiments, electron spin resonance measurements, and photoelectrochemical comprehensive analysis, it is confirmed that BVO@CdS composites have constructed an efficient Z-scheme heterojunction via in situ growth, thereby highly enhancing the separation and transport efficiency of charge carriers.

Magnetically separable CuFe2O4/ZnIn2S4 heterojunction photocatalyst for simultaneous removal of Cr(VI) and CIP

Although photocatalytic has been widely applied for wastewater treatment, there is still a need to develop highly efficient materials capable of simultaneous removal of pollutants and heavy metal ions. This study used a combination of electrospinning and solvothermal methods to prepare CuFe2O4/ZnIn2S4 (CFO/ZIS) heterojunction photocatalysts, and studied their photocatalytic performance in a Cr(VI)-Ciprofloxacin (CIP) coexisting pollutant system. Under simulated sunlight irradiation, the optimal ratio of CFO/ZIS composites (CFO/ZIS-2) achieved a reduction rate of about 99% for Cr(VI) within 20 min, and a degradation rate of about 73% for CIP within 60 min. In addition, even under real sunlight or lake water conditions, CFO/ZIS-2 has the ability to simultaneously remove Cr(VI) and CIP. Most importantly, after the completion of the photoreaction, the magnetism of CFO/ZIS-2 itself can be easily separated with a magnet, indicating that CFO/ZIS-2 has certain practical application capabilities. In addition, cyclic experiments have shown that CFO/ZIS-2 has a certain degree of repeatability and demonstrated that the formation of heterojunctions inhibits photo-corrosion of the catalyst. The formation of heterojunctions in CFO/ZIS-2 was demonstrated through free radical capture experiments and molecular probe experiments, which reduced the recombination of photo-generated electron-holes and enhanced light absorption. This work will provide a new avenue for designing novel magnetic separation and photo-corrosion-resistant photocatalysts to cope with complex wastewater environments.

In vitro evaluation of the antioxidant potential of derivatives eugenol via ABTS radical capture assay

Eugenol is a natural product present in different plant species, especially in the flower buds of Syzygiu Aromatum. This secondary metabolite exhibits antioxidant action, in addition to acting as an anti-inflammatory, antitumor, antibacterial, antifungal, antipyretic, anesthetic and analgesic agent. Given the biological potential of eugenol, the antioxidant activity of eugenol derivatives was evaluated. Thus, eugenol isolated from flower buds of Syzygiu aromaticum was subjected to different types of reactions such as O-alkylation. The eugenol derivatives were characterized by 1H and 13C NMR techniques. The evaluation of antioxidante activity was carried out using the ABTS radical capture assay. Six derivatives were synthesized with yields ranging from 75-92%, which exhibited low antioxidant potential compared to radical capture assays, with EC50 values from 0.085 to 0.327 mg/mL. These results motivate new studies, since the search for new antioxidant agents is extremely necessary in view of the numerous pathologies that are associated with oxidative stress.

High-efficiency photocatalytic degradation of Rhodamine B and tetracycline by Z-scheme nanostructured Ag/Ag3PO4/Ti3+-TiO2 mesocrystals heterojunctions under visible light

This paper discusses the photocatalytic properties of Ag/Ag3PO4/Ti3+-TiO2 composites. The nanostructured composites were synthesized by gas-phase hydrolysis, precipitation, and photoreduction methods. The photocatalytic performance of the photocatalysts was evaluated by degrading RhB and TC under visible light. The degradation efficiency of AT4 for RhB and TC reached 99.9 % and 78.2 % under visible light irradiation for 20 min and 2.5 min, respectively. The superior performance of AT4 is facilitated by the combined influence of the heterojunction and the SPR. The free radical capture test proved that h+ and •O2− were the major reactive groups, and in conjunction with UV–vis DRS curves and Mott-Schottky curves, a probable reaction mechanism was proposed.

Self-assembled composite heterojunction material PDIsm/BiOCOOH promotes photocatalytic degradation of levofloxacin

A broad-spectrum responsive organic-inorganic heterojunction was synthesized by in-situ self-assembled perylene diimide (PDIsm) through π-π stacking onto the surface of flower-like BiOCOOH. The PDIsm/BiOCOOH with different compositions exhibited enhanced photocatalytic degradation of levofloxacin under visible light irradiation. Among them, 10% PDIsm/BiOCOOH had the best photocatalytic activity, which was 4.6 and 14.1 times higher than pure PDIsm and BiOCOOH, respectively. The enhancement of photocatalytic activity was mainly attributed to the introduction of PDIsm which significantly improved the light absorption in almost the whole visible light range. Besides, the formed heterojunctions facilitate the separation and transfer of photogenerated charge carriers. In addition, after five cycles of degradation, the degradation rate of the PDIsm/BiOCOOH composite for levofloxacin hydrochloride remained above 75%, indicating its good photocatalytic activity and stability. Furthermore, free radical capture experiments and electron spin resonance experiments verify that •O2‾ and h+ were the active species generated in the photocatalytic process. Combining the experimental results of high-performance liquid chromatography-mass spectrometry, a possible photocatalytic reaction mechanism was proposed. This work provides a way to prepare an efficient organic-inorganic photocatalyst, which can potentially be utilized in environmental remediation under visible light.

Synthesis of novel g-C3N4/CaTiO3/CQDs heterojunction photocatalyst with enhanced visible light photocatalytic performance

In this paper, a high-efficient visible light responsive g-C3N4/CaTiO3/CQDs Z-type heterojunction photocatalyst was successfully prepared by a two-step method for the photodegradation of organic pollutants in water. The combination of g-C3N4, CaTiO3 and CQDs could produce synergistic effect, which facilitated the separation of carriers, thereby enhancing photocatalytic activity. The photocatalytic kinetic removal rate of g-C3N4/CaTiO3/CQDs for methylene blue could reach about 8 times of g-C3N4 and 5.5 times higher than that of CaTiO3. The effects of co-existing ions, initial pH, water source, and humic acid on meloxicam degradation were examined. Repeatability experiments indicated that the composite had good reusability and stability with 81.1 % removal for meloxicam after four cycles. The main active substances of g-C3N4/CaTiO3/CQDs in free radical capture experiment was ⋅O2−. Possible degradation pathways of meloxicam were also analyzed. The results highlight the g-C3N4/CaTiO3/CQDs Z-type heterojunction is a desirable photocatalyst for removing organic pollutants in water.

Design, preparation, and photocatalytic performance of MoSe2 quantum dots modified BiOCl composite photocatalysts

BiOCl-based heterojunctions with effective charge separation/transportation are highly desired for photocatalytic degradation of pollutants. Fantastic 0D/2D heterojunctions between MoSe2 Quantum dots (QDs) and BiOCl (MoSe2 QDs/BiOCl) were synthesized via liquid phase exfoliation and hydrothermal method. X-ray diffraction, scanning electron microscope, and transmission electron microscopy confirm the excellent crystallinity and the superior surface morphology of the combination of the two materials. The UV–Vis Diffuse Reflectance Spectroscopy shows that MoSe2 QDs/BiOCl exhibits enhanced light absorption. Furthermore, electrochemical impedance spectroscopy and photoluminescence measurements suggest that the MoSe2 QDs/BiOCl heterojunction promotes charge separation and transport of photogenerated carriers. As results, the optimized MoSe2 QDs/BiOCl with 0.5 wt% of MoSe2 QDs significantly enhances the degradation rate of Rhodamine B to 3.59 times (2.76 × 10−3 min−1) that of pristine BiOCl (7.66 × 10−4 min−1). Free radical capture experiments indicate that ·O2− plays an overwhelming role in the Rhodamine B degradation, compared to h+ or ·OH. Our experiments provide some new ideas for improving the photocatalytic degradation performance of BiOCl.

Preparation, structural analysis, efficient photocatalytic degradation mechanism and pathway for p-nitrophenol of Ag-deposited Co-coordination polymer composites

This study addressed the problem of photogenerated charge complexation in coordination polymers (CPs), a considerable barrier to stable, high-performance photocatalysts, by hydrothermally preparing a novel cobalt coordination polymer, [Co(DDB)0.5(PTP)(DMA) (H2O)2]·H2O (Co-CP) using the mixed ligands 1,4-di(3,5-dicarboylphenoxy) benzene (H4DDB) and 4′-(4′′-pyridyl)-2,4′,6′,4′′-terpyridine (PTP). Theoretical calculations have demonstrated that the metal-to-ligand charge transfer (MLCT) in Co-CP is crucial in enhancing charge separation efficiency. Additionally, a silver-deposited composite (Ag@Co-CP) was synthesized through photoreduction. With 1.65wt% Ag, the Ag@Co-CP-2 composites exhibited optimal photocatalytic degradation of various organic pollutants, including nitroaromatic, rhodamine B, methylene blue, basic magenta, and methyl orange. Using charge-coupled devices, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, density functional theory, electron spin resonance measurements, and liquid chromatography-mass spectrometry, we extensively examined the morphology, structure, and photoelectric properties of the developed materials. Our exploration of the structural-activity relationship was supported by results from these structural and optoelectronic analyses. Free radical capture tests and analyses of electron spin resonance led us to pinpoint ·O2−, h+, and ·OH as significant contributors to the reaction system. Finally, we outlined the degradation process, reaction mechanism, and potential pathways. This study contributes to the critical task of designing interfaces between noble metals and semiconductors for improved photocatalytic performance.

Aldehyde-free and bio-based durable coatings for cellulose fabrics with high flame retardancy, antibacteria and well wearing performance

The bio-based coatings of cellulose fabrics (cotton) had attracted increasing attention for multifunction and sustainability but suffered from poor durability and low efficiency. Here, the aldehyde-free and durable coatings for cotton fabrics (CPZ@CF) with satisfactory flame retardancy, antibacteria as well as wearing performance were prepared through the interfacial coordination effect where the well-organized zinc phytate complex were in situ grew on the pre-treated surface of cotton fabrics with chitosan (CS) and Zn2+. The CZP@CF exhibited excellent antibacterial activity for Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) with 99.99 % antibacterial rates benefiting from the synergistic effect between Zn2+ and CS. Meanwhile, even the CPZ coatings loading was only 1.5 wt%, the fire safety of CZP@CF remarkably enhanced owing to the excellent synergistic catalytic charring and free radical capture. More importantly, the antibacterial rates of CZP@CF for S. aureus and E. coli still reached 99.99 % and 91.67 % after 50 washing cycles. Additionally, this treatment method did not deteriorate the fabrics properties, including mechanical and breathability as well as wearing performance, which provided the approach to fabricate the flame retardant and antibacterial textiles with well durability and wearing performance.

The powerful combination of 2D/2D Ni-MOF/carbon nitride for deep desulfurization of thiophene in fuel: Conversion route, DFT calculation, mechanism

2D/2D Ni-MOF/g-C3N4 nanocomposite was utilized for desulfurization. The multilayer pore structure and high specific surface area of Ni-MOF/g-C3N4 promote the adsorption and conversion of thiophene. In addition, the two-dimensional structure exposes more active centers and shortens photogenerated carrier migration to the material surface distance, it enhances photogenerated charge transfer. The Ni-MOF and g-C3N4 construct a Z-scheme heterojunction structure with tight contact, it effectively enhances the material's photocatalytic redox ability. In the light, the material generates more photocarriers for the production of free radicals including hydroxyl radicals, holes, and superoxide radicals. The higher carrier concentration of Ni-MOF/g-C3N4 promotes the activation and oxidation of thiophene, consequently enhancing the photocatalytic desulfurization capability. The results showed that the conversion of thiophene was 98.82 % in 3 h under visible light irradiation. Radical capture experiments and analysis using electron paramagnetic resonance spectroscopy demonstrated that superoxide radicals, holes, and hydroxyl radicals played crucial roles in PODS (photocatalytic oxidative desulfurization). In addition, DFT (density functional theory) calculations were conducted to determine the paths of electron migration and TH (thiophene) adsorption energy. Finally, a mechanism for photocatalytic desulfurization was proposed based on the comprehensive analysis of theoretical calculations and experimental studies.

Reduced graphene oxide membrane confined bimetallic organic framework boosts Fenton-like process to ultrafast contaminants degradation

Fenton-like processes generate reactive oxygen species (ROS) to achieve degradation of organic pollutants, however, practical water treatment processes suffer from low ROS utilization owing to its ultra-short lifetime and mass transfer limitations. To solve these problems, a nano-confined reaction space was designed to facilitate a fast mass transfer process for efficient removal of organic pollutants. Herein, the CuCo-based bimetallic organic framework (CuCo-MOF) was loaded in the water-transporting interlayer nanochannels of reduced graphene oxide (rGO) membrane. Membrane-confined CuCo-MOF with multiple exposed reaction sites activate peroxymonosulfate (PMS), generating ROS for ultrafast removal of oxytetracycline (OTC) at a water fluxes of 87.3 L·m−2·h−1. Notably, this membrane can continuously and stably degrade OTC (100 %) within 30 h. In addition, free radical capture experiments and EPR analysis indicated that the main ROS of the reaction system were singlet oxygen (1O2) and sulfate radical (SO4−). Based on Fukui index results and LC-MS analysis, reaction sites of OTC attacked by ROS were identified and it’s possible degradation pathways were proposed.

2D/2D Bi2MoO6/CoAl LDH S-scheme heterojunction for enhanced removal of tetracycline: Performance, toxicity, and mechanism

In this paper, the two-dimensional (2D) layered CoAl LDH (CoAl) was coupled with Bi2MoO6 (BMO) nanoplate and used for tetracycline (TC) degradation. Based on the results of UV–visible diffuse reflectance spectrum (UV–vis DRS), Motty-Schottky curves, and in situ X-ray photoelectron spectroscopy (XPS), a novel 2D/2D Bi2MoO6/CoAl LDH S-scheme heterojunction photocatalyst was built. The photodegradation rate constant of TC by the optimized sample BMO/CoAl30 was 3.637 × 10−2 min−1, which was 1.26 times and 4.01 times higher than that of Bi2MoO6 and CoAl LDH, respectively. The favorable photocatalytic performance of the heterojunction was attributed to the increased interfacial contact area of the 2D/2D structure. Besides, the transfer of photogenerated electrons from Bi2MoO6 to CoAl LDH under the effect of the built-in electric field (BIEF) reduced the recombination of photogenerated carriers and further improved the photocatalytic performance. The reactive species of h+, ·O2−, and 1O2 exhibited critical roles to degrade TC molecules by reactive radicals capture experiments and electron spin resonance (ESR) tests. The intermediate products of TC degradation and toxicity of intermediates were analyzed by liquid chromatography-mass spectrometer (LC-MS) and Toxicity Estimation Software Tool (T.E.S.T). Additionally, the BMO/CoAl composite photocatalysts showed high stability and environmental tolerance during the testing of cycles and environmental impacts with various water sources, organic contaminants, initial pH, and inorganic ions. This work provides a new protocol for designing and constructing novel 2D/2D S-scheme heterojunction photocatalysts for wastewater treatment.

Facile synthesis of oxygen-deficient BiOBrxCl1−x solid solutions for efficient photocatalytic degradation of organic pollutants

In this study, a series of oxygen-deficient BiOBrxCl1−x (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) solid solution photocatalysts by the microwave hydrothermal method. By changing the Br/Cl molar ratio, the light absorption edge of BiOBrxCl1−x was effectively red-shifted from 345 to 430 nm. The performance of BiOBr0.3Cl0.7 solid solution catalyst showed the best photocatalytic duty for the degradation of norfloxacin (NOR) and methyl orange (MO). The degradation rate of NOR reached 90.2% within 50 min (catalyst dosage: 20 mg), whereas that of MO reached 82.7% within 30 min (catalyst dosage: 5 mg). Environmental factors affecting the degradation of NOR by BiOBr0.3Cl0.7 (such as pH, type of inorganic anions, amount of catalyst, and concentration of NOR) were discussed in detail. The presence of oxygen vacancies (OVs) was confirmed by electron spin resonance (ESR) experiments. Furthermore, free radical capture and ESR experiments identified the main active free radicals involved in the degradation of NOR over BiOBr0.3Cl0.7. Finally, a possible photocatalytic degradation mechanism was proposed.

Furan-based fluorescent probe free radical capture membrane: Analysis of RO2 radical composition and transformation mechanism in urban atmosphere

Peroxyl radicals (RO2) are important components of atmospheric radical cycling and generation, but their formation, distribution and evolution mechanisms in the atmospheric environment have not been investigated. In this paper, we propose a novel atmospheric RO2 radical trapping membrane that can trap low carbon number (Rc ≤ 5) RO2 radicals and identify their R-group structures by fluorescence spectroscopy and chromatography. We also analyzed the composition and evolution mechanism of RO2 species under different meteorological conditions in the atmospheric environment of Lanzhou, China, to provide scientific support for the treatment and research of atmospheric chemical pollution.

Synthesis of novel Cu2WS4/Bi2WO6 heterojunctions and evaluation of their photocatalytic activity for removal of tetracycline under visible light irradiation

In order to change the photocatalytic performance of bismuth tungstate monomer material, the Z-type heterojunction Cu2WS4/Bi2WO6 (CWS/BW) system was formed by loading Cu2WS4 on Bismuth tungstate by hydrothermal method, and then characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). It was concluded that the crystallinity of Cu2WS4/Bi2WO6 system varied with the change of the composite ratio, and no impurity influence was found. The morphology of Cu2WS4/Bi2WO6 system reflects the flower bulbous formed by the superposition of Cu2WS4 nanosheets and Bi2WO6 nanosheets. The overall analysis shows that Cu2WS4 and Bi2WO6 were successfully compounded. Through the characterization analysis of ultraviolet–visible diffuse reflectance absorption spectra (UV–Vis DRS), photoluminescence spectrogram (PL) and N2 adsorption-desorption isotherm analysis (BET), it was concluded that the Cu2WS4/Bi2WO6 system had a higher specific surface area, a wider light corresponding range and a lower photogenerated electron-hole recombination rate.Experiments show that the 5-CWS/BW in the Cu2WS4/Bi2WO6 system had the strongest photocatalytic effect under visible light, and the light degradation rate in 100min can reach 80%, which is 1.7 times and 3.2 times that of monomer Bi2WO6 and Cu2WS4, respectively. 5-CWS/BW still had high activity under different experimental conditions. Later, cyclic experiments proved that the material had strong stability. Finally, the main active substances in photocatalysis were clarified through free radical capture experiments and electron spin resonance (ESR) technology, and the photocatalytic mechanism of Cu2WS4/Bi2WO6 system was inferred.

3D flower-shaped g-C3N4/MoS2 composite with structure defect for synergistic degradation of dyes

Three dimensions (3D) flower-shaped g-C3N4/MoS2 composite was prepared by immobilizing molybdenum disulfide (MoS2) on carbon nitride (C3N4) with structural defects by in-situ hydrothermal assay. The morphological structure and photochemical properties of the obtained catalysts were characterized by SEM, TEM, EDS, FTIR, XRD and XPS. Using methylene blue (MB) as the target pollutant, the photocatalytic performance cyclic stability of g-C3N4/MoS2 composite were studied under simulated sunlight. The results showed that the prepared catalyst could remove 98 % of MB within 60 min and still reached 96.4 % after 5 cycles with good stability and regeneration. Its apparent rate constant was 0.0523 min−1, which was 11.5, 8.2 and 13.9 times higher than those of g-C3N4 (0.00453 min−1), C3N4 with structural defects (0.00635 min−1) and MoS2 (0.00377 min−1), indicating that the synergistic effect of structural defects, heterojunctions and 3D structure has achieved efficient degradation of MB. Furthermore, the photocatalytic mechanism of g-C3N4/MoS2 composite was proposed by combining free radical capture experiment and electron paramagnetic resonance (EPR) spectroscopy and the results showed that that ·OH and ·O2- played a primary role in the catalytic degradation.