Ultraviolet-visible Diffuse Reflectance Spectroscopy Research Articles

Combinatorial effects of non-thermal plasma oxidation processes and photocatalytic activity on the inactivation of bacteria and degradation of toxic compounds in wastewater.

The simultaneous presence of hazardous chemicals and pathogenic microorganisms in wastewater is tremendously endangering the environment and human health. Therefore, developing a mitigation strategy for adequately degrading toxic compounds and inactivating/killing microorganisms is urgently needed to protect ecosystems. In this paper, the synergetic effects of the photocatalytic activity of TiO2 and Cu–TiO2 nanoparticles (NPs) and the oxidation processes of non-thermal atmospheric pressure plasma (NTAPP) were comprehensively investigated for both the inactivation/killing of common water contaminating bacteria (Escherichia coli (E. coli)) and the degradation of direct textile wastewater (DTW). The photocatalytic NPs were synthesized using the hydrothermal method and further characterized employing field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), ultraviolet-visible diffuse reflection spectroscopy (UV-Vis DRS) and photoluminescence (PL). Results revealed the predominant presence of the typical anatase phase for both the flower-like TiO2 and the multipod-like Cu–TiO2 structures. UV-Vis DRS and PL analyses showed that the addition of Cu dopants reduced the bandgap and increased oxygen defect vacancies of TiO2. The inactivation of E. coli in suspension and degradation of DTW were then examined upon treating the aqueous media with various plasma alone and plasma/NPs conditions (Ar plasma, Ar + O2 plasma and Ar + N2 plasma, Ar plasma + TiO2 NPs and Ar plasma + Cu–TiO2 NPs). Primary and secondary excited species such as OH˙, O, H and N2* generated in plasma during the processes were recognized by in situ optical emission spectrometry (OES) measurements. Several other spectroscopic analyses were further employed to quantify some reactive oxygen species (ROS) such as OH, H2O2 and O3 generated during the processes. Moreover, the changes in the pH and electrical conductivity (EC) of the solutions were also assessed. The inactivation of bacteria was examined by the colony-forming unit (CFU) method after plating the treated suspensions on agar, and the degradation of organic compounds in DTW was further validated by measuring the total organic carbon (TOC) removal efficiency. All results collectively revealed that the combinatorial plasma-photocatalysis strategy involving Cu–TiO2 NPs and argon plasma jet produced higher concentrations of ROS and proved to be a promising one-step wastewater treatment effectively killing microorganisms and degrading toxic organic compounds.

Z-scheme heterojunction of Bi2S3/g-C3N4 and its photocatalytic effect

In this study, Bi2S3/g-C3N4 binary catalyst has been excellently prepared by a wet impregnation-calcination method to form Z-scheme heterojunction. The catalyst has been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS) and photoluminescence spectroscopy (PL). The physicochemical properties of the catalyst have been tested, such as crystal structure, morphology, optical properities, light absorption properties and luminescence properties. The results demonstrate that the photocatalytic activity is significantly increased when Bi2S3 with optimum weight percentage (5wt%) loaded into g-C3N4. Through photocatalytic degradation experiments, the optimal loading ratio, dosage and dye concentration of binary materials have been explored. At the same time, the effect of pH on the photocatalytic experiment under the optimal conditions is studied. Reactive blue 19 (RB19) is degraded by 97.77% in 2 h as the target pollutants. The trapping experiment further verified that ꞏO2 - is the main active species in photocatalytic degradation of RB19.

Surface plasmon resonance metal-coupled biomass carbon modified TiO2 nanorods for photoelectrochemical water splitting

Exploring efficient and stable photoanode materials is a necessary link to realize the practical application of solar-driven photoelectrochemical (PEC) water splitting. Hence, we prepared rutile TiO 2 nanorods, with a width of 50 nm, which was growth in situ on carbon cloth (TiO 2 @CC) by hydrothermal reaction. And then, Ag nanoparticles (NPs) and biomass N,S-C NPs were chosen for the additional modification of the fabricated TiO 2 nanorods to produce broccoli-like Ag-N,S-C/TiO 2 @CC nanocomposites. According to the result of ultraviolet–visible diffuse reflectance spectroscopy (UV–vis) and PEC water splitting performance tests, Ag-N,S-C/TiO 2 @CC broadens the absorption region of TiO 2 @CC from the ultraviolet region to the visible region. Under AM 1.5G solar light irradiation, the photocurrent density of Ag-N,S-C/TiO 2 @CC is 89.8 μA·cm −2 , which is 11.8 times higher than TiO 2 @CC. Under visible light irradiation, the photocurrent density of Ag-N,S-C/TiO 2 @CC reaches to 12.6 μA·cm −2 , which is 21.0 times higher than TiO 2 @CC. Moreover, Ag-N,S-C/TiO 2 @CC shows a photocurrent responses in full pH range. It can be found that Ag NPs and N, S-C NPs play key roles in broaden the absorption range of TiO 2 nanorods to the visible light region and, promote the occurrence of PEC water oxidation reaction due to the surface plasmon resonance effect of Ag NPs and the synergistic effect of N,S-C NPs. The mechanism demonstrated that Ag-N,S-C/TiO 2 @CC can separate the photogenerated electron-hole pairs effectively and transfer the photogenerated electrons to the photocathode (Pt plate) in time. This research provides a new strategy for exploration surface plasma metal coupled biomass carbon materials in the field of PEC water splitting.

Investigation of electronic structure, morphological features, optical, colorimetric, and supercapacitor electrode properties of CoWO4 crystals

Cobalt tungstate (CoWO4) crystals were synthesized by the co-precipitation (CP) and polymeric precursor (PP) methods with posterior heat treatment at 800 °C for 4 h. The electronic structure, morphological features, optical, colorimetric, and supercapacitive properties were investigated in detail. X-ray diffraction, Rietveld refinement data, micro-Raman spectra, and Fourier transform-infrared spectra proved the crystallization of both CoWO4 materials with a wolframite-type monoclinic structure. Rietveld refinement data were employed as input data to simulate all clusters found in this crystalline structure as well as electron density maps. These results indicated the existence of distortions in both octahedral [CoO6] and [WO6] clusters, yielding an inhomogeneous charge distribution in the monoclinic lattice. Field emission scanning electron microscopy and transmission electron microscopy techniques show the presence of asymmetrical CoWO4 crystals. The ultraviolet–visible diffuse reflectance spectroscopy revealed optical band energy values of 2.84 and 2.89 eV for CoWO4 crystals prepared by the CP and PP methods, respectively. Colorimetric results indicated that the CoWO4 crystals have a desirable feature for the development of blue inorganic pigments. The experimental specific capacitance measurements of CoWO4 crystals as an electrode (CP and PP) were 192.5 Fg−1 and 249.1 Fg−1 at 40 mV s−1 and 5 mV s−1 in an electrode with 0.4 mg and 0.8 mg of electroactive materials in 1 M Na2SO4 solution, respectively.

Z-scheme WO3/PANI heterojunctions with enhanced photocatalytic activity under visible light: A depth experimental and DFT studies

A WO3@PANI heterojunction photocatalyst with a various mass ratio of polyaniline to WO3 was obtained via the in situ oxidative deposition polymerization of aniline monomer in the presence of WO3 powder. The characterization of WO3@PANI composites was carried via X-ray diffraction (XRD), scanning electron microscopy (SEM-EDS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible diffuse reflection spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL). The photocatalytic efficiency of WO3@PANI photocatalysts was assessed by following the decomposition of the Rhodamine B (RhB) dye under visible light irradiation (λ >420 nm). The results evidenced the high efficiency of the WO3@PANI (0.5 wt %) nanocomposite in the photocatalytic degradation of RhB (90% within 120 min) under visible light irradiation 3.6 times compared to pure WO3. The synergistic effect between PANI and WO3 is the reason for the increased photogenerated carrier separation. The superior photocatalytic performance of the WO3@PANI catalyst was ascribed to the increased visible light in the visible range and the efficient charge carrier separation. Furthermore, the Density Functional Theory study (DFT) of WO3@PANI was performed at the molecular level, to find its internal nature for the tuning of photocatalytic efficiency. The DFT results indicated that the chemical bonds connected the solid-solid contact interfaces between WO3 and PANI. Finally, a plausible photocatalytic mechanism of WO3@PANI (0.5 wt %) performance under visible light illumination is suggested to guide additional photocatalytic activity development.

Preparation of TiO2 Nanotube Using Anodization Method: Charactherization and Its Application for CO Sensor

Preparation of highly ordered TiO 2 nanotube arrays (HOTNAs) by anodization of Ti foil industrial grade in ethylene glycol electrolyte containing 0.3% of ammonium fluoride and 2% of water at 30 V for 90 minutes was conducted. The morphology structure, chemical composition, functional group, crystal phase, and optical properties of HOTNAs were characterized by field emission scanning electron microscope (FE-SEM), Energy Dispersive X-Ray (EDX),Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), and ultraviolet visible diffuse reflectance spectroscopy (UV/Vis-DRS). The well-ordered nanotube with vertically oriented structure was formed in the HOTNAs having size in diameter, length, and wall thickness of 48,0 nm, 1,8 µm, and 26,7 nm, respectively. The fabricated HOTNAs were evaluated for their sensing properties for CO detection. The results show that the fabricated HOTNAs were able to detect 2500 ppm of CO gas with response about 93,429 at operation temperature 150 ° C. This preliminary study of sensing performance demonstrates that the prepared HOTNAs under this study is potential and promising as a material sensor for CO detection.

Visible- light responsive PPynt@NH2-MIL-125 nanocomposite for efficient reduction of Cr(VI)

The present investigation aims to remove Cr(VI) by PPynt@NH2-MIL-125 nanocomposite material under visible light irradiation.In this paper, a new photocatalyst material was prepared by using traditional conductive polymer polypyrrole nanotube (PPynt) and MOFs (NH2-MIL-125), and was characterized by Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), XPS, ultraviolet-visible diffuse reflectance spectroscopy (UV–VIS/DRS), and transmission electron microscopy (TEM). PPynt is also conducive to the separation and transferring of charge carriers, as well as the improvement of activity because the conductivity of PPynt provides a good electron transport path. The result shows that 5% PPynt@NH2-MIL-125 has superior photocatalytic activity and a 99.02% Cr(VI) reduction. On this basis, we systematically studied the effect of different pH and concentrations on the reduction system.

Improved visible light photocatalytic degradation of yttrium doped NiMgAl layered triple hydroxides for the effective removal of methylene blue dye

Fabrication of layered triple hydroxides (LTH) is a typical and remarkable approach to produce new functionalities passionately investigated for photocatalytic removal of organic pollutants from industrial wastewater. The hydrothermal method was used to prepare different weight percentages of yttrium (Y) doped NiMgAl LTH. The structural, functional, optical, and morphological properties of the prepared samples were investigated using X-ray diffraction, Fourier transformed-infrared spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, and scanning electron microscopy. The photocatalytic degradation of the different percentages of Y-doped LTH samples were assessed through the photocatalytic degradation of methylene blue dye under the visible light irradiation. When compared to other lower concentrations of Y doping, the photocatalytic degradation efficiency of 1 wt.% Y-doped LTH was higher. Thus, the optimized LTH's improved photocatalytic performance was attributed to increased visible light absorption with low transmission and improved electron-hole separation.

Tailoring Bi2MoO6 by Eu3+ incorporation for enhanced photoluminescence emissions

Here, an experimental study is presented on the structural, electronic, and optical properties of Bi2-xMoO6:xEu3+ (x = 0, 0.5, 1.0, 2.0, and 4.0 mol%) materials, synthesized by means of the microwave-assisted solvothermal method using ethylene glycol as a solvent. Different characterization techniques (X-ray diffraction measurements with Rietveld refinements, Raman and ultraviolet–visible diffuse reflectance spectroscopy, field emission scanning electron microscopy, and photoluminescence emissions) have been employed to examine the structural and electronic properties, energy transfer and defect evolution which control the performance of the as-synthetized materials. Present findings provide deep insights into the substitution of Eu3+ cations in Bi2MoO6, with focus on their influence on process that dictate the superior optical properties.

Visible-light-activated TiO2–NiFe2O4 heterojunction for detecting sub-ppm trimethylamine

Trimethylamine (TMA), which mainly emanates from decaying fish, is an important freshness indicator of seafood. In this work, a TiO2–NiFe2O4 heterojunction was successfully synthesized for TMA detection using a simple and efficient hydrothermal method. The materials were characterized using X-ray diffraction, scanning electron microscopy, photoluminescence spectroscopy, and ultraviolet–visible diffuse reflectance spectroscopy. The TiO2–NiFe2O4-based sensor exhibited the largest response (12) to 10 ppm of TMA at 307 ℃. The response was further improved under white-light irradiation, increasing from 2.5 to 4.5 as the TMA concentration approached 3 ppm. The enhanced gas-sensing performance of the TiO2–NiFe2O4 sensor under light irradiation was then explored by density functional theory (DFT) with an optical carrier. We believe that the developed strategy improves the gas-sensing ability for TMA detection and can potentially be used in gas sensors.

Synthesis of Z-scheme g-C3N4/V2O5photocatalyst with high activity under visible light

Direct Z-scheme g-C3N4/V2O5 photocatalysts were prepared through a sonication-assisted calcination method. The obtained samples were characterised by X-ray diffraction (XRD),Ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis-DRS), Scanning electron microscope (SEM), andPhotoluminescence spectroscopy (PL). Oxidations of tetracycline hydrochloride (TC) were employed to evaluate the photocatalytic activities of the obtained g-C3N4/V2O5materials. Different weight ratios (5, 10, 15, and 20%) of g-C3N4/V2O5 loaded composites were prepared, in which a 15% (CV-15) loaded composite was found to show optimal catalytic performance for the reaction. The degradation conversation of TC has achieved approximately 79.67% in CV-15 after a 2-hour reaction. g-C3N4/V2O5 photocatalystwas more active than the individual g-C3N4 and V2O5 materials, which could be attributed to the efficient separation of photogenerated electron-hole pairs shown in the photocatalytic mechanism of TC degradation.

Anchoring bismuth oxybromo-iodide solid solutions on flexible electrospun polyacrylonitrile nanofiber mats for floating photocatalysis

Constructing floating photocatalysts with highly efficient visible-light utilization is a promising approach for practical photocatalytic wastewater treatment. In this study, we anchored bismuth oxybromo-iodide (BiOBrxI1-x (0 ≤ x ≤ 1)) on flexible electrospun polyacrylonitrile (PAN) nanofiber mats to create BiOBrxI1-x@PAN nanofibers with tunable light absorption properties as floating photocatalysts at room temperature. As x increased, the photocatalytic activity of the BiOBrxI1-x@PAN nanofibers with similar loading content initially increased, and then decreased, for the degradation of bisphenol A (BPA) and methyl orange (MO) under visible-light irradiation (λ > 420 nm) conditions. The BiOBrxI1-x@PAN (0 < x < 1) nanofibers exhibited better photocatalytic performance compared to the BiOBr@PAN and BiOI@PAN nanofibers. Under visible-light irradiation, the BPA degradation rate of the BiOBr0.5I0.5@PAN nanofibers was 1.9 times higher than that of the BiOI@PAN nanofibers, while the BiOBr@PAN nanofibers had no noticeable degradation performance. The MO degradation rate of the BiOBr0.5I0.5@PAN nanofibers was 2.5 and 3.2 times higher than that of the BiOBr@PAN and BiOI@PAN nanofibers, respectively. The enhanced performance possibly originated from a balance between the light absorption and redox capabilities, along with efficient separation of electron-hole pairs in the BiOBr0.5I0.5@PAN nanofibers, as determined by ultraviolet-visible diffuse reflectance spectroscopy, X-ray photoelectron spectra analysis of the valence bands, and photocurrent response characterization. Compared to the powder structures, the BiOBrxI1-x@PAN nanofibers showed enhanced performance due to the excellent dispersion and immobilization of the BiOBrxI1-x solid solution, which provided more active sites during photocatalytic degradation. In addition, their flexible self-supporting structures allowed for floating photocatalysis near the water surface. They could be reused directly without separation and maximized the absorption of visible light during the photocatalytic reaction. Therefore, these solid-solution-based floatable nanofiber photocatalysts are good potential candidates for wastewater treatment applications.

Efficient degradation of orange II by core shell CoFe2O4–CeO2 nanocomposite with the synergistic effect from sodium persulfate

Novel core shell CoFe2O4–CeO2 (CoFe–Ce) nanocomposite was synthesized and investigated as an efficient photocatalyst to activate sodium persulfate (Na2S2O8, PS) for orange Ⅱ (OⅡ) degradation. The CoFe–Ce nanocomposite was successfully designed and synthesized by a facile hydrothermal reaction followed by calcination and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), and vibrating sample magnetometer (VSM). Compared with pure CoFe2O4 and CeO2, the photocatalytic efficiency of CoFe–Ce nanocomposite was significantly improved. Under the irradiation of visible light, the catalytic degradation efficiency of orange II could reach to 98.5% within 60 min. Additionally, the as-prepared material could be recycled for at least five times using magnetic separation ability of the nanocomposite, and during the cycling the dye degradation rate was almost unchanged. The active species produced during the degradation were studied by classical quenching experiments, and the different types of free radicals produced in the system were further confirmed by electron paramagnetic resonance (EPR) spectroscopy. This novel nanocomposite is expected to have potential application for degradation of organic pollutants in wastewater by utilizing solar energy.

Synthesis of CdS nanomaterials and their photocatalytic activity under visible light

CdS nanomaterial was hydrothermally synthesized at 160 oC for 6 hours from a dispersed mixture of Cd(NO3)2.4H2O and CH3CSNH2 in 50 mL ethylenediamine and denoted as Cw-m, where w-m is the weight ratio of Cd(NO3)2.4H2O/CH3CSNH2 and equals to 1-2, 1-1 and 3-2. The obtained materials were characterized by X-Ray Diffraction (XRD), Infrared spectra (IR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Energy-dispersive X-ray (EDX), and Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV-Vis-DRS). The UV-vis DRS showed that the CdS materials possess bandgap of around 2.24 eV. The photocatalytic activity of the CdS was assessed by degradation of methylene blue (MB) under visible light. The experiments indicated that CdS semiconductor materials can be active under visible light. The MB degradation over the CdS was mainly attributed to the photoreduction process induced by the superoxide radical anions (O2• -) and hydroxyl radicals (•OH).

Synthesis of Mo-Modified TiO2 Material with Enhanced Photocatalytic activity

The Mo-modified TiO2 was synthesized via facile impregnation combined with pyrolysis of mixtures in several different initial mass ratios of precursors as mTi(OH)4/m(NH4)6Mo7O24.4H2O equaling 5, 10 and 15 in 500 oC for an hour. The as-prepared samples, denoted as n-MT-500 within n for the initial mass ratio of precursors, were characterized by X-ray diffraction, scanning electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy, Raman spectroscopy, as well as X-ray photoelectron spectroscopy, which all not only illustrate the presence of TiO2 and MoO3 components in the composites but also demonstrate the introduction of Mo hetero-atom into anatase lattice. All of the obtained samples performed higher photocatalytic activity under visible light than TiO2 via the photodecomposition of RhB in aqueous solution, in which 10-MT-500 exhibits the highest degradation efficiency up to 87% after 5-hour illumination.

Performance and mechanism of biochar-coupled BiVO4 photocatalyst on the degradation of sulfanilamide

The construction of a low-cost and efficient novel photocatalyst is extremely important for the treatment of refractory wastewater. In this work, biochar-coupled BiVO4 (CBi) photocatalysts are synthesized using a hydrothermal method. These photocatalysts are then characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transition electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet visible diffuse reflection spectroscopy (UV–Vis-DRS), and photoluminescence (PL). The photocatalytic performance was also evaluated using the degradation and mineralization of sulfaniamide (4-aminobenzene sulfonamide, SA) under visible light irradiation. The results indicated that the CBi photocatalysts showed larger surface areas, stronger absorption abilities, higher separation efficiencies of photogenerated electrons and holes, and powerful transfer abilities of photogenerated electrons than the photocatalyst without biochar (CBi-0%). The CBi photocatalyst with the 20 wt% biochar (CBi-20%) exhibited an optimal photodegradation ability for SA. The degradation rate of SA was approximately 97.0% after 7 h of visible light irradiation, and the removal rate of total organic carbon (TOC) was as high as 83.4%, indicating an excellent mineralization ability. In addition, the CBi-20% photocatalyst obtained the highest mineralization rate of organic nitrogen (92.7%) and organic sulfur compounds (75.8%). Furthermore, spectroscopic techniques revealed more information regarding the degradation of the benzene ring and fluorescent groups. The fluorescence intensity and UV254 of SA were reduced by 96.5%% and 90.0%, respectively, which provided specific evidence of the potential photodegradation mechanism.

Bimodal Ultrasound and X-ray Bioimaging Properties of Particulate Calcium Fluoride Biomaterial.

Ultrasound (US) and X-ray imaging are diagnostic methods that are commonly used to image internal body structures. Several organic and inorganic imaging contrast agents are commercially available. However, their synthesis and purification remain challenging, in addition to posing safety issues. Here, we report on the promise of widespread, safe, and easy-to-produce particulate calcium fluoride (part-CaF2) as a bimodal US and X-ray contrast agent. Pure and highly crystalline part-CaF2 is obtained using a cheap commercial product. Scanning electron microscopy (SEM) depicts the morphology of these particles, while energy-dispersive X-ray spectroscopy (EDS) confirms their chemical composition. Diffuse reflectance ultraviolet-visible spectroscopy highlights their insulating behavior. The X-ray diffraction (XRD) pattern reveals that part-CaF2 crystallizes in the face-centered cubic cell lattice. Further analyses regarding peak broadening are performed using the Scherrer and Williamson–Hall (W-H) methods, which pinpoint the small crystallite size and the presence of lattice strain. X-ray photoelectron spectroscopy (XPS) solely exhibits specific peaks related to CaF2, confirming the absence of any contamination. Additionally, in vitro cytotoxicity and in vivo maximum tolerated dose (MTD) tests prove the biocompatibility of part-CaF2. Finally, the results of the US and X-ray imaging tests strongly signal that part-CaF2 could be exploited in bimodal bioimaging applications. These findings may shed a new light on calcium fluoride and the opportunities it offers in biomedical engineering.

Zinc oxide nanorods incorporated magnetic isoreticular metal–organic framework for photodegradation of dyes

Cobalt magnetic isoreticular metal – organic framework (CoFe2O4-IRMOF-3) was prepared by facile solvothermal procedure. ZnO nanorods were assembled on the CoFe2O4-IRMOF-3 using a commercial ultrasonic homogenizer. The photocatalytic activity of ZnO-CoFe2O3-IRMOF-3 was investigated by photodegradation of two cationic dyes including methylene blue and rhodamin B. CoFe2O4 and ZnO nanorods were incorporated on the IRMOF-3 to improve the separation and photocatalytic activity of IRMOF-3 under visible light, respectively. The mesoporous nanocomposite was characterized by various techniques including transmission electron microscopy, scanning electron microscopy, energy dispersion x-ray, powder X-ray diffraction, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller, and ultraviolet-visible diffuse reflectance spectroscopy. The zeta potential of synthesized samples showed the surface of all materials was negative charge in the range of the pH experiment (pH 6.5). The results showed that the ZnO-CoFe2O3-IRMOF-3 had extremely degradation ability of MB and RhB molecule due to the synergetic effect between ZnO and CoFe2O4-IRMOF-3 in comparison with IRMOF-3 and CoFe2O4-IRMOF-3. The introduced ZnO on the surface of CoFe2O4-IRMOF-3 incremented degradation of dyes in the visible region and increased the transfer and separation of the generated charge on the contact area between ZnO and CoFe2O4-IRMOF-3. Furthermore, after five times recycling, the separation of ZnO-CoFe2O4-IRMOF-3 from liquid media using magnetic, the composite still showed high photodegradation ability.

One-Step Microwave-Assisted Synthesis and Visible-Light Photocatalytic Activity Enhancement of BiOBr/RGO Nanocomposites for Degradation of Methylene Blue.

In this study, bismuth oxybromide/reduced graphene oxide (BiOBr/RGO), i.e. BiOBr-G nanocomposites, were synthesized using a one-step microwave-assisted method. The structure of the synthesized nanocomposites was characterized using Raman spectroscopy, X-ray diffractometry (XRD), photoluminescence (PL) emission spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and ultraviolet-visible diffuse reflection spectroscopy (DRS). In addition, the ability of the nanocomposite to degrade methylene blue (MB) under visible light irradiation was investigated. The synthesized nanocomposite achieved an MB degradation rate of above 96% within 75 min of continuous visible light irradiation. In addition, the synthesized BiOBr-G nanocomposite exhibited significantly enhanced photocatalytic activity for the degradation of MB. Furthermore, the results revealed that the separation of the photogenerated electron–hole pairs in the BiOBr-G nanocomposite enhanced the ability of the nanocomposite to absorb visible light, thus improving the photocatalytic properties of the nanocomposites. Lastly, the MB photo-degradation mechanism of BiOBr-G was investigated, and the results revealed that the BiOBr-G nanocomposites exhibited good photocatalytic activity.

Synthesis of β-FeOOH/TiO2/SiO2 by melting phase separation-hydrothermal method to improve photocatalytic performance

This paper combines traditional ceramics with advanced ceramics, based on the principle of matching the phase separation temperature of the Na2O–B2O3–SiO2 glass system with the crystallization temperature of TiO2, and uses the melting-phase separation method to directly separate the TiO2 photocatalytic material from the porous glass. The catalyst is tightly combined with the SiO2 carrier, and then the β-FeOOH/TiO2/SiO2 composite material is prepared by the hydrothermal method. X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), infrared spectroscopy (FT-IR) and specific surface area (BET) were used to analyze the crystal structure, morphology and phase composition of the compound. Ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence spectroscopy (PL) are used to characterize the light absorption characteristics of samples. Using tetracycline hydrochloride as a simulated degradation product, the photocatalytic activity of the composite photocatalyst under visible light was studied. The experimental results show that the double-crystal phase glass-ceramics are prepared by the melting phase separation method, the crystal phase is TiO2, and the amorphous phase is SiO2. A heterojunction was successfully constructed between β-FeOOH and TiO2, which effectively improved the migration efficiency of photogenerated carriers and extended the light response range to 640 nm. The photocatalytic efficiency of 0.2β-FeOOH/TiO2/SiO2 composite photocatalyst to tetracycline hydrochloride (TC) is 77 %. After 3 cycles of photocatalytic degradation test, the composite material still maintains good photocatalytic performance, and the crystal structure has not changed. Superoxide free radicals are the main active substance that degrades TC. This provides a reference for the industrial production of glass-phase TiO2-based composite photocatalyst.