Constructing magnetically recoverable CdS/CaFe2O4 P–N heterojunctions for enhanced photoelectrochemical properties towards H2 evolution reaction

A novel CdS/CaFe₂O₄ (CS/CFO) heterogeneous p-n junction was created by thermal deposition of CaFe₂O₄ nanoparticles on CdS rods. The CS/CFO hetero-structured photocatalysts exhibited increasingly efficient visible light harvesting compared to the bare CdS. The CS/CFO composites also presented higher photocurrent and slower decay of photoluminescence, suggesting a better separation of the photo-generated electrons and holes. The photocatalytic H₂ evolution quantity on the optimized CS/CFO composite from water in the presence of ethanol was up to 2200 μmol after 3-h visible light illumination, which is more than twice that of the pristine CdS. The chemical interaction between CdS and CaFe₂O₄ was confirmed by the shifts in the XPS peaks, which made it possible for the charge carriers to transfer across the p-n junction interface. This research highlights the importance of forming an interfacial p-n heterojunction between two semiconductors for efficient charge separation and improved photocatalytic performance.     

Magnetic Fe2O3/CNT nanocomposites: Characterization and photocatalytic application towards the degradation of Rose Bengal dye

In this work, hybrid nanocomposite materials for the wastewater treatment via photocatalysis have been developed by combining multi walled carbon nanotubes (MWCNT) and hematite (α-Fe₂O₃).A straightforward strategy via sonication method has been used to prepare theα-Fe₂O₃/CNT nanocomposites with varying CNT content (5%, 7.5%, and 10%)and characterized by X-ray Diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), and UV–Vis. spectrophotometer. XPS spectra was used to identify the defects/oxygen vacancies in the α-Fe₂O₃ lattice. TEM revealed the well deposition of α-Fe₂O₃ nanoparticles on the CNT surface. α-Fe₂O₃/CNT 10% nanocomposites have higher photocatalytic activity with 87% degradation of Rose Bengal dye in 90 min. The increased photocatalytic activity can be attributed to the synergistic contribution of α-Fe₂O₃ and CNTs, which inhibits photo-generated charge carrier recombination and the formation of highly active radical species (OH^• radicals, and O₂^• radicals) on the surface of CNTs. This research may be useful not only for understanding the photocatalytic mechanism, but also for developing efficient photocatalysts for the organic pollutant degradation.     

Photocatalytic reduction synthesis of SrTiO3-graphene nanocomposites and their enhanced photocatalytic activity

SrTiO₃-graphene nanocomposites were prepared via photocatalytic reduction of graphene oxide by UV light-irradiated SrTiO₃ nanoparticles. Fourier transformed infrared spectroscopy analysis indicates that graphene oxide is reduced into graphene. Transmission electron microscope observation shows that SrTiO₃ nanoparticles are well assembled onto graphene sheets. The photocatalytic activity of as-prepared SrTiO₃-graphene composites was evaluated by the degradation of acid orange 7 (AO7) under a 254-nm UV irradiation, revealing that the composites exhibit significantly enhanced photocatalytic activity compared to the bare SrTiO₃ nanoparticles. This can be explained by the fact that photogenerated electrons are captured by graphene, leading to an increased separation and availability of electrons and holes for the photocatalytic reaction. Hydroxyl (·OH) radicals were detected by the photoluminescence technique using terephthalic acid as a probe molecule and were found to be produced over the irradiated SrTiO₃ nanoparticles and SrTiO₃-graphene composites; especially, an enhanced yield is observed for the latter. The influence of ethanol, KI, and N₂ on the photocatalytic efficiency was also investigated. Based on the experimental results, ·OH, h⁺, and H₂O₂ are suggested to be the main active species in the photocatalytic degradation of AO7 by SrTiO₃-graphene composites.

PACS

61.46. + w; 78.67.Bf; 78.66.Sq     

Synergetic piezo-photocatalytic effect in SbSI for highly efficient degradation of methyl orange

SbSI nanowires (SbSI NWs) and SbSI microrods (SbSI MRs) were synthesized by simple sonochemical and hydrothermal methods, respectively. The SbSI NWs possess better catalytic performance due to the smaller size and larger specific surface area. Meanwhile, the piezoelectric effect and photocatalytic performance of SbSI were combined for the first time. The degradation rate of methyl orange (MO) solution (30 mg/L) by SbSI NWs reaches 97.1% within 2 min under the synergistic effect of visible light and ultrasonic vibration, which is 4.83 times of photocatalysis and 14.22 times of piezocatalysis. The reactive oxide species (ROS) such as hydroxyl radicals (?OH) and superoxide radicals (?O₂^?) were examined by radical trapping experiments to demonstrate their critical role in degrading MO molecule. Furthermore, a possible mechanism of the piezo-photocatalytic process was proposed and degradation pathway of MO dyes by SbSI NWs was suggested based on the HPLC-MS results. It shows that the degradation process of MO includes the breakage of azo double bond, the removal of sulfonic group, the breakage of carbon nitrogen bond, and finally the formation of NO₃^?, SO₄^2?, CO₂ and H₂O. This work provides a promising case for the practical application in dye wastewater treatment of piezoelectric semiconductors.     

Diatom Biosilica Doped with Palladium(II) Chloride Nanoparticles as New Efficient Photocatalysts for Methyl Orange Degradation

A new catalyst based on biosilica doped with palladium(II) chloride nanoparticles was prepared and tested for efficient degradation of methyl orange (MO) in water solution under UV light excitation. The obtained photocatalyst was characterized by X-ray diffraction, TEM and N₂ adsorption/desorption isotherms. The photocatalytic degradation process was studied as a function of pH of the solution, temperature, UV irradiation time, and MO initial concentration. The possibilities of recycling and durability of the prepared photocatalysts were also tested. Products of photocatalytic degradation were identified by liquid chromatography–mass spectrometry analyses. The photocatalyst exhibited excellent photodegradation activity toward MO degradation under UV light irradiation. Rapid photocatalytic degradation was found to take place within one minute with an efficiency of 85% reaching over 98% after 75 min. The proposed mechanism of photodegradation is based on the assumption that both HO^• and O₂^•− radicals, as strongly oxidizing species that can participate in the dye degradation reaction, are generated by the attacks of photons emitted from diatom biosilica (photonic scattering effect) under the influence of UV light excitation. The degradation efficiency significantly increases as the intensity of photons emitted from biosilica is enhanced by palladium(II) chloride nanoparticles immobilized on biosilica (synergetic photonic scattering effect).     

Microwave-assisted synthesis of α-Fe2O3/ZnFe2O4/ZnO ternary hybrid nanostructures for photocatalytic applications

Solar-driven highly efficient photocatalytic decomposition of toxic organic contaminants using magnetically separable α-Fe₂O₃/ZnFe₂O₄/ZnO ternary hybrid nanodiscs is reported. α-Fe₂O₃/ZnFe₂O₄/ZnO ternary hybrid nanostructures were synthesized by microwave-assisted co-precipitation and simple co-precipitation methods and well characterized by XRD, micro-Raman, FESEM and UV–vis spectroscopy. FESEM micrographs revealed nanodiscs in case of microwave-assisted co-precipitation whereas nanoparticles and their aggregates were formed under co-precipitation combined with calcination. XRD and Raman studies confirmed the hybrid nature of prepared α-Fe₂O₃/ZnFe₂O₄/ZnO nanostructures. Photocatalytic performance of α-Fe₂O₃/ZnFe₂O₄/ZnO hybrid nanostructures was investigated by carrying out the photodegradation of organic dyes MB and MG under solar light illumination. The prepared α-Fe₂O₃/ZnFe₂O₄/ZnO ternary hybrid magnetic nanodiscs decomposed MB and MG dyes in only 32 and 24 min, respectively. α-Fe₂O₃/ZnFe₂O₄/ZnO hybrid nanodiscs showed excellent photocatalytic performance together with reusability and easy magnetic separation demonstrating its suitability for solar-driven photocatalytic water purification applications. In-situ scavenger studies showed ?OH radicals are the main active radicals in solar-driven photocatalysis by α-Fe₂O₃/ZnFe₂O₄/ZnO nanodiscs. The tentative mechanism of growth of α-Fe₂O₃/ZnFe₂O₄/ZnO ternary hybrid nanodiscs and the photocatalytic mechanism are discussed.     

Photocatalytic and antibacterial characteristics of decorated polyester textile with ceramic nanoparticles of cobalt ferrite

In this study, a multifunctional textile profiting from photocatalytic activity, magnetic, and antibacterial properties was generated through decorating polyester fabric with cobalt ferrite (CoFe₂O₄) nanoparticles using the co-precipitation technique. The X-ray diffraction (XRD) results supported the successful decoration of fabrics with CoFe₂O₄ magnetic nanoparticles. Field emission electron scanning microscopy (FESEM) images accompanied by energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analyses demonstrated the morphology, dispersion, and chemical structure of particles on the surface. The mean particle size of cobalt ferrite was measured to be approximately 40 nm. Vibrating sample magnetometer (VSM) results confirmed the ferrimagnetic behavior of the decorated fabrics with saturation magnetization (M_s) and coercivity (H_c) of 1.8 emu/g and 1902 Oe, respectively. The UV–vis diffuse reflectance spectrum (DRS) and photoluminescence (PL) data indicated the appropriate performance under visible light irradiation and postponed electron-hole recombination of the decorated fabric, respectively. The maximum MB degradation efficiency of 97% after 180 min of visible light illumination was obtained. The active species trapping analyses indicated that hydroxyl radicals (^●OH) were the effective species in the photocatalytic degradation mechanism. The decorated sample with the best photocatalytic activity revealed more than 99% reduction in the number of colonies against gram-negative and gram-positive bacteria after 24 h contact time, which validated its excellent potential for antibacterial applications. Outstanding photocatalytic and antibacterial characteristics of the decorated textile with cobalt ferrite nanoparticles turn it into promising composite material for self-cleaning purposes.     

Development of internal electric field induced NiFe2O4/CdO p-n nano-heterojunctions for solar light activated photodegradation of methylene blue dye

NiFe₂O₄/CdO nanocomposites were prepared using a facile co-precipitation method. A series of characterization techniques such as X-rays diffraction, Fourier transform infrared spectroscopy, and UV–Visible absorbance spectroscopy were performed to validate that weight percentage of CdO can efficiently manage the textural characterization, crystal size, and other parameters meant for photocatalysis. Experimental findings have shown that the weight percentage of CdO has an influential effect on the photocatalytic degradation of methylene blue (MB) under solar irradiation. Compared with bare NiFe₂O_4, all NiFe₂O₄/CdO composites have shown better photocatalytic activity. Among all composites, NiFe₂O₄/CdO composite with 15% CdO has displayed the best photocatalytic efficiency (72%) for MB degradation. The enhanced photocatalytic activity may be ascribed to the delayed electron-hole recombination and availability of active sites for degradation. Furthermore, NiFe₂O₄/CdO composite could quickly be recovered from the solution using a magnet. Intermediate species trapping experiments have shown that photocatalysis by NiFe₂O₄/CdO is highly dependent on superoxide radicals.     

Mn-modified HfO2 nanoparticles with enhanced photocatalytic activity

Round shaped Mn-modified HfO₂ nanoparticles were prepared by the Pechini type sol-gel method. The effects of Mn ions on the structure, particle growth, composition, optical properties and photocatalytic performance of HfO₂ particles were investigated. The structure analysis revealed that the insertion of Mn²⁺, Mn³⁺, and Mn⁴⁺ ions inhibited the complete stabilization of tetragonal HfO₂. Also, the decrease of particle size to values lower than 5 nm and the shift of optical band gap from 5.7 to 2.1 eV was obtained as effect of increasing the Mn content. HfO₂ nanoparticles modified with 10 w% Mn exhibited the highest photocatalytic performance, reaching an efficiency of 91.93% in the decomposition of methylene blue, after 120 min of sunlight irradiation. The efficient trapping of photogenerated electrons on the surface of these nanoparticles generated •O₂⁻ radicals, which were the main oxidative species involved in the degradation of the dye. The improved photocatalytic performance of these nanoparticles is then attributable to their increased surface area, suitable photoactivation, and effective transport of photoexcited charge carriers. Based in studies of band gap, valence band position and active species, a mechanism of photodegradation for this photocatalyst was also proposed and discussed.     

Innovative synthesis of a novel ZnO/ZnBi2O4/graphene ternary heterojunction nanocomposite photocatalyst in the presence of tragacanth mucilage as natural surfactant

Developing interfacial connections is one of the breakthrough strategies to improve the photocatalytic activity of graphene/p-n heterojunction systems. Herein, natural tragacanth mucilage, for the first time, was employed as cost-effective and ecofriendly surfactant to prepare highly efficient ZnO–ZnBi₂O₄/graphene hybrid photocatalyst. The results indicated that the methylene blue (MB) photocatalytic degradation efficiency of ZnO–ZnBi₂O₄/graphene-mucilage heterojunction, containing 10 wt% ZnBi₂O₄ and 1 wt% graphene, was ～1.2, 1.4, 3.1 and 8.3 times higher than that of ZnO–ZnBi₂O₄/graphene, ZnO–ZnBi₂O₄, ZnBi₂O₄ and ZnO samples, respectively. This significant improvement in the photocatalytic performance could be mainly ascribed to the desirable advantages of using natural mucilage as surfactant, including uniform distribution of ZnO–ZnBi₂O₄ nanoparticles on the surface of graphene sheets, increasing of the effective surface area, and improving of the charge carriers separation. Based on the trapping experiments, electron spin resonance and photoelectrochemical Mott-Schottky tests, direct Z-Scheme charge transfer mechanism with hydroxyl radicals as main active species was suggested for photocatalytic degradation of MB on the ZnO–ZnBi₂O₄/graphene-mucilage nanocomposite. This study provides a new insight to fabricate more homogeneous and close contact interfaces in graphene-based hybrid photocatalytic systems for environmental remediation.     

Degradation of Atenolol in a Rectangular Staircase Photocatalytic Reactor with Immobilized ZnO

Atenolol (ATL) was removed with a rectangular staircase photocatalytic reactor (RSPR) using immobilized ZnO under solar irradiation. The effects of operational parameters such as flow rate, pH, and initial ATL concentration were examined. The highest degradation was obtained after 240 min photocatalytic reaction. The effects of different scavengers proved that the ATL degradation was mainly due to the direct oxidization with OH^? radicals, whereas, the h⁺ and O₂^?? radicals played a minor role in the degradation process. Five repetitive operations of RSPR allowed for reaching 77 ± 3 % degradation of ATL for each cycle. Kinetic data indicated that the photocatalytic kinetics followed the global matter balance model.     

Magnetically recyclable Ni1-xCdxCeyFe2-yO4-rGO nanocomposite photocatalyst for visible light driven photocatalysis

In this study, a magnetically recyclable Ni_1-xCd_xCe_yFe_2-yO₄-rGO (x, y = 0.05) (NCCF-rGO) nanocomposite photocatalyst has been prepared by following a facile in-situ co-precipitation method combined with ultra-sonication means. The as-synthesized magnetically separable NCCF-rGO nanocomposite photocatalyst efficiently degrades methylene blue (MB) dye in comparison to bare Ni_1-xCd_xCe_yFe_2-yO₄ (x, y = 0.05) (NCCF) nanoparticles (NPs) under visible light irradiation. The photo-degradation rate of MB with NCCF-rGO was ~9 times higher than NCCF nanoparticles (NPs). This enhanced photocatalytic performance of NCCF-rGO photocatalyst was due to the presence of reduced graphene oxide, which greatly help in production of photoactive species by reducing the rate of electro-hole pair recombination. The role of photoactive species that were responsible for the photocatalytic degradation of methylene blue has also been investigated. The as-synthesized NCCF-rGO photocatalyst expressed superb chemical stability and photocatalytic activity even after seven cycle runs. Moreover, the NCCF-rGO nanocomposite worked at all pH values and showed good acid resistance. In particular, the as-synthesized NCCF-rGO photocatalyst could be collected for the next cycle run by simply applying an external magnetic field. Hence, the NCCF-rGO nanocomposite could have potential use in organic dyes contained wastewater treatment.     

TiO<Subscript>2</Subscript> porous ceramic/Ag–AgCl composite for enhanced photocatalytic degradation of dyes under visible light irradiation

TiO₂ porous ceramic/Ag–AgCl composite was prepared by incorporating AgCl nanoparticles within the bulk of TiO₂ porous ceramic followed by reducing Ag⁺ in the AgCl particles to Ag⁰ species under visible light irradiation. The porous TiO₂ ceramic was physically robust and chemically durable, and the porous structure facilitated the implantation of AgCl NPs. Compared with the bare TiO₂ ceramic, TiO₂ porous ceramic/Ag–AgCl composite exhibited higher photocatalytic performance for the degradation of MO and RhB under visible light irradiation. The reaction rate constants k of MO and RhB degradation over TiO₂ porous ceramic/Ag–AgCl composite was respectively 6.25 times and 3.62 times higher than those recorded over the bare TiO₂ porous ceramic. The photocatalytic activity showed virtually no decline after four times cyclic experiments under visible light irradiation. Scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, UV–Vis diffuse reflectance spectroscopy, photoluminescence spectra and X-ray photoelectron spectroscopy were used to characterize the TiO₂ porous ceramic/Ag–AgCl composite.     

A novel one-step strategy for preparation of Fe3O4-loaded Ti3C2 MXenes with high efficiency for removal organic dyes

Transition-metal carbides, nitrides or carbonitrides (named as MXenes) are a novel type of two-dimensional (2D) materials with the features of traditional 2D materials but more variable chemical compositions. MXenes and related materials have raised more and more research attention and been extensively explored for different applications. In this work, we developed a novel method to synthesize magnetic MXene composites (Ti₃C₂-MNPs) for the first time through a one-pot route, which relied on the incorporation of Fe₃O₄ nanoparticles into Ti₃C₂ nanosheets via thermal treatment. The potential utilization of these Ti₃C₂-MNPs for catalytic degradation of organic dyes through advanced oxidation processes (AOPs) were also evaluated in details. We demonstrated that Fe₃O₄ nanoparticles with size about 5 nm could be anchored onto Ti₃C₂ with well dispersed state. The catalytic degradation results demonstrated that Ti₃C₂-MNPs possess extremely high degradation efficiency towards different organic dyes under optimal conditions. The electron spin resonance (ESR) spectra identified that both hydroperoxyl radicals (•OH) and superoxide radicals (•O₂^-) radicals were involved in the degradation process. This work reported a novel one-step method for fabrication MXenes based multifunctional composites, which show extremely high efficiency for AOPs. This method could also be extended for fabrication of many other multifunctional composites for various applications.     

A multipath peroxymonosulfate activation process over supported by magnetic CuO-Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles for efficient degradation of 4-chlorophenol

Heterogeneous catalysts with low cost, environmentally friendly, highly effective and ready separation from aqueous solution are highly desirable. Magnetic CuO-Fe₃O₄ nanoparticles, a type of non-toxic bimetallic transition metal oxide, is a promising heterogeneous catalyst for activation of peroxymonosulfate (PMS) to generate reactive oxygen species (ROS) that has not been previously investigated. In this study, the activation of PMS by CuO-Fe₃O₄ nanoparticles was evaluated using the degradation of 4-chlorophenol as a model reaction. Several critical factors such as pH, catalyst dosage and PMS concentration were investigated. CuO-Fe₃O₄/PMS system demonstrated a wide effective pH range to degrade 4-chlorophenol, namely 5.5 to 9.5. With the increase of the catalyst dosage, the degradation efficiency of 4-chlorophenol appeared to increase first and then decrease, that the inflection point was 0.5 g/L. Elevated PMS concentration obviously improved the decomposition of 4-chlorophenol; however, the plateau was reached when the PMS concentration was 8 mM. Further increase in PMS concentration would not significantly improve the removal efficiency. Through examining the effects of scavengers and electron spin resonance (ESR) analyses, CuO-Fe₃O₄ nanoparticles were proven to activate PMS through a non-radical and radical pathway to generate singlet oxygen, sulfate radicals and hydroxyl radicals. Based on results, CuO-Fe₃O₄ nanoparticles were effective, environmentally friendly and low cost catalysts for efficient activation of PMS. These features make CuO-Fe₃O₄ nanoparticles a readily available heterogeneous catalyst to activate PMS for refractory organic pollutants degradation in advanced oxidation processes (AOPs).     

Strong tribocatalytic dye degradation by tungsten bronze Ba4Nd2Fe2Nb8O30

The triboelectric effect has recently demonstrated its great potential in environmental remediation and even new energy applications for triggering a number of catalytic reactions by utilizing trivial mechanical energy. In this study, Ba₄Nd₂Fe₂Nb₈O₃₀ (BNFN) submicron powders were used to degrade organic dyes via the tribocatalytic effect. Under the frictional excitation of three PTFE stirring rods in a 5 mg/L RhB dye solution, BNFN demonstrates a high tribocatalytic degradation efficiency of 97% in 2 h. Hydroxyl radicals (?OH) and superoxide radicals (?O₂－) were also detected during the catalysis process, which proves that triboelectric energy stimulates BNFN to generate electron-hole pairs. The tribocatalysis of tungsten bronze BNFN submicron powders provides a novel and efficient method for the degradation of wastewater dye by utilizing trivial mechanical energy.     

In situ synthesis of Bi2O3/Bi2MoO6 heterostructured microspheres for efficiently removal of acid orange 7

Flower-like Bi₂O₃/Bi₂MoO₆ heterostructured microspheres with excellent photocatalytic performance were successfully constructed by in situ ion exchange and calcination, employing Bi₂MoO₆ microspheres prepared by solvothermal method as raw material and template. Various characterization techniques including XRD, FE-SEM, EDS, UV–vis DRS and XPS have been adopted to analyze the composition, structure and optical absorption property of the obtained sample. Their photocatalytic properties for degrading acid orange 7 (AO7) were investigated with visible light. Experimental results show that all Bi₂O₃/Bi₂MoO₆ composites have a higher catalytic activities than pure Bi₂MoO₆. Remarkably, 0.2Bi₂O₃/Bi₂MoO₆ show best activity and the degradation efficiency is up to 99% under visible light for 100?min, which is ascribed to the synergistic effect and big heterojunction interface, and promoting rapid transmission of photogenerated charge. Moreover, There is negligible reduction on the degradation efficiency after catalysts was reused for 4 times. The photogenerated holes (h⁺) and superoxide radical anions (?O₂^-) were major active species by radical scavenger experiments. A possible mechanism is proposed to explain rationally enhancement of photocatalytic activity.     

Ag@AgCl quantum dots embedded on Sn3O4 nanosheets towards synergistic 3D flower-like heterostructured microspheres for efficient visible-light photocatalysis

Taking advantage of the oil-water interface, we introduced Ag@AgCl quantum dots (QDs) onto 2D Sn₃O₄ nanosheets to fabricate a composite photocatalyst with a 3D flower-like structure (denoted as Ag@AgCl/Sn₃O₄). Using the degradation of tetracycline hydrochloride (TC-HCl) and methylene blue (MB) as the examples, the as-prepared Ag@AgCl/Sn₃O₄ composite with Ag@AgCl weight loading of 1% indicated 9.6 and 7.88 times higher photocatalytic activity than the Sn₃O₄ nanosheets. Within both degradation reactions, hydroxyl radicals (•OH) and superoxide radicals (•O²⁻) were identified as the critical oxidation intermediates based on radical trapping and electron spin resonance (ESR) experiments. The unique morphology and photoelectrochemical properties of the as-prepared composites suggested the introduced Ag@AgCl QDs cooperated with the Sn₃O₄ semiconductor to enhance the utilization of solar energy. Overall, the established heterojunction helped to reduce the transfer barrier of the photoinduced charge carriers, wherein the surface plasmonic resonance (SPR) of Ag nanoparticles was believed to take the main responsibility. The present work combines the Ag@AgCl-QDs and flower-like 3D Sn₃O₄ microspheres for the first time to achieve an impressive degrading rate of TC-HCl and MB at the Ag@AgCl weight loading as low as 1%.     

Photocatalytic performance of β-Ga2O3 microcubes towards efficient degradation of malachite green

In this work, the photocatalytic degradation of malachite green (MG) solutions by β-Ga₂O₃ was investigated. The latter was synthetized by reacting gallium nitrate with concentrated formic acid, which produced gallium formate. The thermal decomposition of this compound at 850 °C produced single-phase β-Ga₂O₃. The resulting morphology corresponds to non-agglomerated microcubes, with a size in the range of 0.8 and 2.3 μm. The surface chemical composition and bandgap energy of this oxide were determined by X-ray photoelectron spectroscopy (XPS) and the Tauc method, respectively. The photodegradation of MG was carried out under violet light (λ = 405 nm), at room temperature, using the as-prepared powder. The results revealed a fast degradation of the dye during the first 20 min, which attenuates over time. The rate of photodegradation depends on the amount of β-Ga₂O₃ used and can be fitted by an exponential equation. The role of free hydroxyl radicals and reactive oxygen species in photocatalysis was addressed by using analytic techniques (FTIR and XPS).     

A novel magnetic photocatalyst Bi3O4Cl/SrFe12O19: Fabrication,characterization and its photocatalytic activity

A novel Bi₃O₄Cl/SrFe₁₂O₁₉ magnetic photocatalyst has been fabricated by a hydrothermal-roasting method. Its structure and performance were studied through XRD, XPS, SEM, UV–vis DRS, PL, EIS and VSM, and the photocatalytic property was tested by photodegradation of RhB irradiation with solar-simulated light. The optimum sample of Bi₃O₄Cl/SrFe₁₂O₁₉(20%) displayed the excellent photocatalytic activity, and the degradation rate was more than 99.7% in 80 min. In addition, the Bi₃O₄Cl/SrFe₁₂O₁₉(20%) showed the quite high magnetic performance, of which the saturation magnetization was 7.65 emu·g⁻¹ and the recovery percent was 92.4%. Meantime, the product revealed the great photocatalytic stability, with the photodegradation leave reaching 84.1% after five cycles. The trapping experiments demonstrated that the hydroxyl radicals, photoproduction holes and superoxide radicals played a critical part in photodegrading of RhB. This research provided a new method to synthesize composite magnetic photocatalyst and studied the possible photodegradation mechanism.