Degradation Rate Of MB Research Articles

Template-Free Hydrothermal Synthesis of Octahedron-, Diamond-, and Plate-like ZrO2 Mono-Dispersions.

Anisotropic ZrO particles with octahedron-, diamond- and plate-like morphologies are successfully synthesized by a facile hydrothermal treatment approach using NaBF as mineralizer. The concentration of mineralizers play a crucial role on the formation of shape-controlled ZrO particles thus affect the particle size. With the increasing concentration of mineralizer, the crystalline sizes of the primary single-crystal and the secondary particle size both increase. With the introduction of NaBF, F plays an essential role in tuning the crystallinity and size of primary ZrO nanorods along [001] direction. The synergistic effect of F and B result in different epitaxial growth rate. And the secondary particles mainly crystallize on the small primary nanoparticles through the oriented attachment mechanism. The as-prepared ZrO particles with different sizes and shapes exhibit different photocatalytic efficiency for the degradation of organic dyes. Under UV irradiation, the highest MB degradation rate of 88% was observed within 60 min for ZrO photocatalyst synthesized with 0.01 mol/L NaBF mineralizer.

Preparation and performance evaluation of BiOI photocatalytic film

BiOI photocatalyst powder was prepared using the hydrothermal method. Using BiOI, PAN as the solute and DMF as the solvent, the mixed solution was stirred uniformly, and the photocatalytic film was prepared by an electrospinning machine. The microscopic morphology, pore size, and contact angle were characterised by scanning electron microscopy, N2 adsorption and desorption, and contact angle tests. The photocatalytic performance of the film at different calcination temperatures was explored. The results show that the film has the best photocatalytic performance under the heat treatment conditions of 280℃ and 6 h, and the degradation rate of MB to 10 mg/L is 94.3 %. Meanwhile, different cycles of experiments show that the film photocatalyst has good stability and strong mechanical properties. After four cycles of experiments, the film showed almost no damage and the degradation rate could still reach 93.6 %. The films showed good degradation potential of organic dye wastewater and have good application prospect.

Crystalline TiO2 shell microcapsules modified by Co3O4/GO nanocomposites for thermal energy storage and photocatalysis

Modified microcapsule is devised to achieve the integration of thermal energy storage and light energy conversion of solar energy. This composite structure integrates the nanomaterial composed of graphene oxide (GO) and Co3O4 nanoparticles, on the microencapsulated paraffin coated by crystalline TiO2 shell. Compared with TiO2@paraffin microcapsules, introducing a thermal conductivity improved element of Co3O4/GO substantially increased the thermal conductivity by 57.7% and retained specific heat capacity of 2.154 J·g−1·K−1 and latent heat above 140 J·g−1. Microcapsules exhibited full-spectrum sunlight absorption ability, and the photothermal conversion efficiency was increased by 88.9%. Microcapsules are connected to the oxygen-containing functional groups on the flat of Co3O4/GO via hydrogen bonds and shared electron pairs, constituting a highly efficient Z-scheme heterojunction. By synergistic catalysis of photothermal, synergetic effects of semiconductor, and plasma resonance, the degradation rate of MB increased by 70.75%. This sophisticated multilevel structure of microcapsule possessed outstanding thermal cycling stability, which retains high thermal conductivity and specific heat capacity for microcapsule, while the latent heat loss rate was only 1.26%. This research implies a new insight for the field of energy storage microcapsules modification and multifunctional utilization of solar energy.

An efficient construction method of S-scheme Ag2CrO4/ZnFe2O4 nanofibers heterojunction toward enhanced photocatalytic and antibacterial activity

The combination of multiple optimization methods has become one of the hot strategies for the development of novel photocatalysts. Therefore, in this paper, the S-scheme Ag2CrO4/ZnFe2O4 (ACO/ZFO) nanofibers heterojunction photocatalyst is successfully prepared by co-precipitation method by loading ACO particles on the surface of ZFO nanofibers. It is found that ACO/ZFO composites not only have the advantages of higher specific surface area and more exposed active sites, but also the successful construction of S-scheme heterojunction effectively inhibits the recombination of photoelectron-hole pairs and generates more active groups, showing its superior redox ability. ACO/ZFO composites have excellent photocatalytic performance under the enhancement of multiple properties. The results showed that under the simulated visible light, the 40%ACO/ZFO composite with the best photocatalytic activity has the highest sterilization rate of 98.7%, which is 2.1 times and 3.3 times of ACO and ZFO, respectively, and the degradation rate of MB is 3.1 times and 4.7 times of ACO and ZFO, respectively. The mechanism of S-scheme ACO/ZFO nanofibers heterojunction photocatalyst was investigated by free radical experiment. This work provides new insights into the design and development of S-scheme heterojunctions for environmental remediation and sterilization.

Covellite nanoparticles with high photocatalytic activity bioproduced by using H2S generated from a sulfidogenic bioreactor

The application of sulfate reducing bacteria (SRB) has emerged as an efficient biotechnology to reduce sulfate to sulfide and to mediate the precipitation of transition metals as sulfides. In the present work, hydrogen sulfide biogenerated by the SRB was delivered into a copper aqueous solution vessel to produce copper sulfide nanoparticles. The main physico-chemical properties were studied by TEM, XRD, UV–vis spectroscopy, fluorescence spectroscopy, UPS and XPS. In addition, the photocatalytic activities for organic dyes removal were investigated, showing a high degradation rate of MB and RD in aqueous solution. By changing the copper concentration during the synthesis process, main physico-chemical properties of copper sulfides nanoparticles can be controlled. For the lowest concentration, pure covellite flake-like nanostructures were produced. Higher concentrations produced spherical-like shapes with the presence of SO42− on the surface. Experimental results showed a promising way to obtain valorous copper sulfides nanoparticles by using dissimilatory reduction of sulfate mediated by SRB.

Nanofibers based quaternary CeO2/Co3O4/Ag/Ag3PO4 S-scheme heterojunction photocatalyst with enhanced degradation of organic dyes

Nanofibers-based materials are among the promising photocatalysts for degrading organic pollutants. In this work, CeO2/Co3O4 nanofibers, which absorb a wide spectrum of visible light, were prepared by electrospinning technique. Then, the quaternary CeO2/Co3O4/Ag/Ag3PO4 step-scheme composites were synthesized by precipitation route. Various characterizations like FE-SEM, EDS, DRS, XRD, XPS, PL and FT-IR were conducted to determine the morphology, structure and properties of samples. The photocatalytic efficiency of as-prepared composites were investigated by the degradation of MB under blue LED light irradiation. Quaternary CeO2/Co3O4/Ag/Ag3PO4 composites exhibit higher photocatalytic performance than CeO2 and CeO2/Co3O4. Particularly, this composite yielded 92.5% degradation of MB in 80 min, and the degradation rate of MB by the photocatalyst was almost 0.03 min−1, which was 4.8 times faster than that over CeO2/Co3O4 NFs. The significant increase in the reaction rate of MB photo-degradation can be related to SPR effect, the inhibition of charge–carrier recombination and formation S-scheme system.

Photodegradation Attenuated Oscillation:A Novel Photocatalytic Characteristic for the Polymetallic Oxide Semiconductor Porous Materials with Energy Bandgap Gradient

AbstractSamples of metal oxide SnO2 and its composite SnO2/Bi2O3, ploymetallic oxides SnO2/Bi2O3/CdO, SnO2/Bi2O3/Fe2O3, and SnO2/Bi2O3/CdO/Fe2O3 powder materials were successfully prepared by a simple solid‐state reaction method at room temperature using sodium benzenesulfonate (SBS) surfactant as template. The synthesized powder materials were characterized by X‐ray diffraction (XRD), UV‐vis diffuse reflectance spectrum (UV‐Vis), scanning electron microscopy/energy dispersive X‐ray (SEM/EDX), infrared spectroscopy (IR), X‐ray photoelectron spectroscopy (XPS), N2 adsorption‐desorption and the migration rate testing of charges. Moreover, the adsorption characteristic and photodegradation performance of methyl blue (MB, co=100 mg/L) on the materials were investigated. The results show that the degradation rate (94.2 %) of MB on the SnO2/Bi2O3/CdO/Fe2O3 nanomaterial is the highest than that of the other materials within 10 min under the visible‐light irradiation. After that, the photodegradation rate of MB on the as‐prepared SnO2/Bi2O3/CdO, SnO2/Bi2O3/Fe2O3 and SnO2/Bi2O3/CdO/Fe2O3 semiconductor materials with energy band gap gradient generates the novel phenomena of photo‐ degradation attenuated oscillation but absent for the SnO2/Bi2O3 and SnO2 materials. It may be originated from the presence of the phase‐transitions of α‐Bi2O3 and β‐Bi2O3, the change ratio of Fe3+ and Fe2+ in the photocatalytic process, and the characteristic adsorption of MB molecular groups by the different metal oxides. This provides new ideas for future inspiring continued research on this emerging class of mixed metal oxides semiconductors and thereby enables innovations.

Modified coal tailings with TiO2 nanotubes and their application for methylene blue removal

Coal tailings are complex materials of low value that discharged from a coal-cleaning plant. These types of solid waste own great application prospects, but so far their utilization is still rare. Water pollution is another noteworthy problem in the world today. Organic pollutants such as dyes must be removed from the water. In the face of increasingly serious problems of water pollution and coal tailings reuse, it is an innovative method to treat organic wastewater with materials prepared by coal tailings. In this work, a series of TiO 2 Nanotubes (TNTs) with Modified Coal Tailings (MCTs) prepared by different methods (including NaOH activation, H 2 SO 4 activation and calcination) were successfully synthesized by a hydrothermal method using MCTs and Tetrabutyl titanate as starting materials. The different influencing factors on the photocatalytic performance of TNT-MCTs composites were characterized through XRD, SEM, EDS, TEM, UV–vis DRS, FT-IR and BET surface measurements. The UV–vis DRS spectra revealed that the absorption edge of TNTs is 387 nm, while that of TNT-MCTs photocatalysts redshifts up to 393 nm. The photocatalytic activity of TNT-MCTs was evaluated by the photocatalytic depigmentation of methylene blue solution (MB, 10 mg/L) under UV light irradiation. The specific surface area, surface roughness and activity of MCTs were increased after loading with TNTs. The degradation rate of MB reached 91% in 60 min under UV light illumination.

Influences of Fe[sbnd]Mn ratio on the photocatalytic performance of wolframite (FexMn1-xWO4)

Natural semiconducting minerals are widely distributed in supergene environments and are famous for their solar-driven redox activities, in which wolframite (FexMn1-xWO4) as a fascinating member got less attention. In this work, the semiconducting photocatalytic activities of FexMn1-xWO4 series samples (x = 1, 0.74, 0.48, 0.24, 0) influenced by their crystal chemistry were investigated. The bandgaps of MnWO4, Fe0.24Mn0.76WO4, Fe0.48Mn0.52WO4, Fe0.74Mn0.26WO4 and FeWO4 as measured by UV–vis diffuse reflection (DRS), were 2.7, 2.4, 2.3, 2.2, and 2 eV, respectively, which were linearly decreased (R2 = 0.971) when x increased from 0 to 1. The density functional theory (DFT) calculations further indicated with the increasing content of Fe, the contribution of valence-band maximum (VBM) was stepwise occupied by Fe 3d orbits and the bandgap was thus gradually decreased. The photocatalytic activities of FexMn1-xWO4 samples were examined on the degradation of methylene blue (MB, 5 mg/L). The MB removal rate was the highest in Fe0.74Mn0.26WO4 system, which was 3.2, 1.9, 1.2, and 1.5 times faster than that of MnWO4, Fe0.24Mn0.76WO4, Fe0.48Mn0.52WO4, and FeWO4, respectively. The concentration of produced hydroxyl radical (•OH) by FexMn1-xWO4, detected in electron paramagnetic resonance (EPR) measurement, had a positive correlation with the degradation rate of MB. The degradation rate slowed down when •OH was removed, demonstrating that •OH was the major reactive oxygen species in the photocatalytic oxidative degradation of MB. The best-performing Fe0.74Mn0.26WO4 photocatalytically produced the most •OH, which was closely linked with its most abundant oxygen-vacancy defects, revealed by X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectroscopy. It thus can be concluded that narrow bandgap and appropriate oxygen vacancies can give rise to synergistic effect on the improvement of photocatalytic performance. This study helps get insight into the role of crystal chemistry in semiconducting properties and photocatalytic activities of wolframite, which also puts forward a new strategy to control environmental pollution by using natural minerals.

Adsorption and Photocatalytic Properties of Modified Rectorite-Titanium Dioxide Composites

Using rectorite as raw material, REC is modified by nitric acid, TiO2 is attached to the surface of the acidized modified REC tablet to form modified REC-TiO2 composite materials by the sol-gel method, and its adsorption performance and photocatalytic properties were studied. The results show that the adsorption of REC, modified REC, modified REC-TiO2 composite materialtoporads to methylene blue increased with the increase of equilibrium concentration. The process of adsorption MB of modified REC-TiO2 composite materials is an endothermic process. The adsorption of REC, modified REC, modified REC-TiO2 composite materials to MB increased with the increase of temperature. When the temperature is 25 degree, the maximum adsorption capacity of REC is 93.985 mg/g, the maximum adsorption capacity of modified REC is 107.006 mg/g, and the maximum adsorption capacity of modified REC-TiO2 is 120.773 mg/g. The degradation rate of MB and p-nitrophenol by modified REC-TiO2 composite under illumination are 99% and 98%, respectively. The decontamination rate of MB and 4-NP of modified REC-TiO2 composites under darkness was 50% and 0.8%, respectively. Under light conditions, the degradation rate of MB and 4-NP in modified REC-TiO2 composite materials is improved.

Cu-doped TiO2 brookite photocatalyst with enhanced visible light photocatalytic activity

Abstract Cu-doped TiO2 having a brookite phase and showing enhanced visible light photocatalytic activity was synthesized using a mild solvothermal method. The as-prepared samples were characterized by various techniques, such as X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectroscopy. Photocatalytic activity of Cu-doped brookite TiO2 nanoparticles was evaluated by photodegradation of methylene blue under visible light irradiation. The X-ray diffraction analysis showed that the crystallite size of Cu-doped brookite TiO2 samples decreased with the increase of Cu concentration in the samples. The UV-Vis diffuse reflectance spectroscopy analysis of the Cu-doped TiO2 samples showed a shift to lower energy levels in the band gap compared with that of bare phase brookite TiO2. Cu doped brookite TiO2 can obviously improve its visible light photocatalytic activity because of Cu ions acting as electron acceptors and inhibiting electron-hole recombination. The brookite TiO2 sample with 7.0 wt.% Cu showed the highest photocatalytic activity and the corresponding degradation rate of MB (10 mg/L) reached to 87 % after visible light illumination for 120 min, much higher than that of bare brookite TiO2 prepared under the same conditions (78 %).

Enhanced the photocatalytic activity of B–C–N–TiO2 under visible light:Synergistic effect of element doping and Z-scheme interface heterojunction constructed with Ag nanoparticles

In order to enhance the photocatalytic activity of TiO2 under visible light, Ag nanoparticles were introduced into tridoped B–C–N–TiO2 (TT) catalyst by photoreduction deposition. Ag/B–C–N–TiO2 (ATT) catalysts with the functions of reducing band gap and carrier recombination were prepared. At the same time, the effect of the amount of Ag on the photocatalytic performance of ATT catalyst was investigated. Through XRD, XPS, PL and other characterization methods, the (211)/(101)/Ag interface heterojunction mechanism similar to the traditional Z-scheme heterojunction was proposed. The intervention of Ag nanoparticles changed the P–N interface heterojunction between (211)/(101) to the (211)/(101)/Ag Z-scheme interface heterojunction. The results show that ATT catalyst exhibits the highest photocatalytic activity when the molar amount of Ag is 0.005% with the MB degradation rate of the ATT catalyst (0.01707 min−1), which is 14.59 times of TiO2 (0.00117 min−1) and 2.02 times of TT (0.00847 min−1). In addition, the four cycles efficiencies of ATT for MB degradation were all above 94.00%.This study reveals the possibility of construction of Z-scheme heterojunctions between precious metal nanoparticles and different interfaces of TiO2, and provides a reference for the construction of Z-scheme interface heterojunctions.

Yb-substitution triggered BiVO4-Bi2O3 heterojunction electrode for photoelectrocatalytic degradation of organics

As a photocatalyst with visible light response, BiVO4 has been widely investigated for organic wastewater treatment. However, its catalytic activity is greatly restricted because the photogenerated electrons and holes would recombine easily. Herein, we took a Yb-substitution strategy to construct BiVO4-Bi2O3 heterojunction for improving spatial separation of photogenerated electrons and holes. XRD, XPS, FESEM, and TEM investigations demonstrated that Yb-substitution can change the structure of BiVO4 and trigger the formation of BiVO4-Bi2O3 heterojunction. The photoeletrocatalytic activity of the as-synthesized composites was verified by degradation of MB under simulated sunlight. More importantly, the photoeletrocatalytic activity of 0.04Yb-BiVO4-Bi2O3 composite was significantly improved, resulting from the successful construction of BiVO4-Bi2O3 heterointerfaces. Moreover, the 0.04Yb-BiVO4-Bi2O3 composite displayed the best the catalytic performance, and the degradation rate of MB under simulated sunlight irradiation and an applied bias voltage of 1.0 V can reach 83.2 % within 2 h.

Effect of different forms of nano‐ZnO on the properties of PVDF/ZnO hybrid membranes

AbstractIn this article, polyvinylidene fluoride (PVDF)/ZnO hybrid membranes with different forms of nano‐ZnO as additives were prepared by thermally induced phase separation. The effects of the morphology of ZnO particles on the microstructure and properties of hybrid membranes were systematically investigated. Three different forms of nano‐ZnO were characterized by X‐ray diffraction (XRD) and scanning electron microscope (SEM). Then a series of tests were made through XRD, Fourier transform infrared, differential scanning calorimeter, SEM, energy‐dispersive X‐ray spectroscopy, atomic force microscopy, mechanical strength testing, porosity measurement, water contact angle measurement, pure water flux measurement, rejection measurement, flux recovery rate (FRR) measurement, and photocatalytic degradation testing to characterize the hybrid membrane. The results show that the hybrid membranes which were doped with different forms of ZnO have different structures and properties. Porous ZnO has the best modification effect on PVDF membranes. The PVDF/porous ZnO hybrid membranes' water flux and OVA rejection can reach 1.6 and 1.3 times of pure PVDF membrane, respectively, and its FRR can reach about 95%. The hybrid membrane doped with porous ZnO has excellent self‐cleaning performance, and its degradation rate of MB can reach about 51%.

The performance of daylight photocatalytic activity towards degradation of MB by the flower-like and approximate flower-like complexes of graphene with ZnO and Cerium doped ZnO

Semiconductor photocatalysts have played an important role in degrading water pollution in recent years. In this paper, the effects of graphene on the structure, morphology, optical properties and photocatalytic activity of ZnO and Ce-doped ZnO were studied. The photocatalysts of ZnO, Ce doped ZnO (ZnCeO), ZnO-Graphene (ZG), Ce doped ZnO-Graphene (ZGCeO) were synthesized via one-step hydrothermal method and were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), ultraviolet visible absorption (UV–vis). The results of XRD show the synthesized samples were all ZnO phases without impurity peaks. The prepared ZnO was hexagonal wurtzite crystal structure. A flower-like ZG and an approximate flower-like ZGCeO were characterized via SEM. The UV–vis spectra shows that the absorption edges have red-shifts and the absorption band broaden in all doped or composite samples, meanwhile, the band gap energy decreased from 3.26 eV to 3.06 eV. In addition, compared with pure ZnO, the photocatalytic activity of ZnCeO, ZG and ZGCeO are improved. Among them, ZGCeO shows superior photocatalytic activity: the degradation rate of organic dye MB was 99.17 % in 90 min under simulated solar irradiation.

Natural wolframite as a novel visible-light photocatalyst towards organics degradation and bacterial inactivation

Tungstate oxide is a new kind of anionic semiconductor material, which has been received much attention due to its good photocatalytic performance and long-term stability. To facilitate large-scale application, the natural counterpart of tungstate oxide, wolframite, was firstly used as a visible-light mineral photocatalyst in this study. Its mineralogical and photocatalytic properties were characterized and compared with two synthetic end-member minerals, FeWO4 and MnWO4. The results showed natural wolframite in the form of (Fe,Mn)WO4, had a bandgap of only 1.5 eV, far lower than that of FeWO4 (2.3 eV) and MnWO4 (2.6 eV). Under visible-light, natural wolframite exhibited remarkable photoactivity towards degradation of methylene blue (MB, 5 mg/L) and disinfection of Escherichia coli K-12 (107 cfu mL−1) under neutral pH. The MB degradation rate in the presence of both wolframite and H2O2 was as 3-fold or 14-fold as that in the controls without light or H2O2, respectively. And the disinfection rate using wolframite was at least 5 times higher than that using MnWO4 or FeWO4. Hydroxyl radical (OH•), as detected by electron paramagnetic resonance, was demonstrated as the major reactive oxygen species by using different scavengers in the photocatalytic reactions. The production of OH• was due to both photocatalytic and photo-Fenton effects. Recycling experiments were conducted to demonstrate the long-term stability and photoactivity of wolframite, in which the MB degradation rate almost kept unchanged after three experimental rounds. Our results indicated that natural wolframite could be used as a promising visible-light driven photocatalyst applied for large-scale wastewater treatment.

Persulfate enhanced visible light photocatalytic degradation of organic pollutants by construct magnetic hybrid heterostructure

In this study, three kinds of magnetic visible light photocatalysts (Fe3O4/GCN) were successfully prepared by a two-step method. The maximum magnetic property of the as-prepared composite was Fe3O4-op/GCN-3, with a maximum magnetization of 13.77 emu/g. Fe3O4/GCN exhibits excellent visible-light-driven photocatalytic activity for the degradation of organic pollutants. Among them, with regard to Fe3O4-ht/GCN-2, it was found that the degradation rate of MB is 2.37 times higher than that of GCN under visible light condition. On the one hand, one of the mechanisms for enhancing photocatalytic effect of composite material is the decrease of the band gap width. On the other hand, the generated photoelectrons can be transferred to Fe3O4 nanoparticles, which can effectively reduce the recombination of photogenerated electron-hole pairs. And the Fe3O4/GCN + visible light hybrid activation systems exhibited higher significant efficiency for organic pollutants degradation combined with PS. The maximum removal rate of MB, AB I, BP-5R,TC and BPA can reach 96.69%, 89.34%, 81.62%, 62.57% and 53.21%, respectively. This is mainly due to the hybrid activation system under visible light radiation can significantly accelerate the activation rate of S2O82−. The trapping experiment results investigations suggested that SO4•- and h+ are the main radical species in photocatalytic decomposition process. In addition, •OH species were then generated from the reduction of SO4•- by photo-electron.

Preparation of Phosphorus and Oxygen Co-Doped With Graphite Carbon Nitride and Its Application in Photodegradation of Methylene Blue

In this study, phosphorus and oxygen co-doped graphite carbon nitride has been successfully prepared by simple thermal copolymerization. The as-prepared materials were characterized by SEM, XRD, XPS and UV-vis-DRS. The results showed that phosphorus and oxygen were successfully doped on the structure of graphite carbon nitride. Photocatalytic degradation of MB in solution by the catalyst has been studied, POCN-1 has the best photocatalytic activity among of the as prepared materials, photocatalytic degradation rate of MB is 10.6 times higher than that of g-C3N4. The main reason for its enhanced photocatalytic performance is that the co-doped of phosphorus and oxygen elements would change the electronic structure of g-C3N4, reduce the forbidden band width of the photocatalyst. At the same time, can extend the absorption boundary of visible light.

Z-scheme mpg-C3N4/Ag6Si2O7 heterojunction for highly efficient photocatalytic degradation of organic pollutants under visible light

The mpg-C3N4/Ag6Si2O7 hybrid photocatalyst was successfully prepared via in situ precipitation of Ag6Si2O7 on mpg-C3N4 surface using a facile ultrasonic-assisted wet-chemical method and characterized by FE-SEM, TEM, HRTEM, XRD, FTIR, BET, XPS and UV–vis DRS analysis to study its morphology, composition, surface structure, chemical state and light absorption property. The effects of mass percentages of mpg-C3N4/(mpg-C3N4+Ag6Si2O7) on photocatalytic performence of the hybrid photocatalyst were investigated. The results showed that 4% mpg-C3N4/Ag6Si2O7 hybrid exhibited greatly improved photocatalytic activity for different organic dyes and colorless 2,4-dichlorophenol degradation under visible light and the photocatalytic degradation rate of MB by it attains 2.31 times that by sole Ag6Si2O7 and 51 times that by sole mpg-C3N4, and is also much higher than that by mechanical mixture of Ag6Si2O7 and mpg-C3N4 with the same mass percentage of mpg-C3N4, confirming the existence of the synergistic effect of Ag6Si2O7 and mpg-C3N4 in 4% mpg-C3N4/Ag6Si2O7 hybrid. High stability after three recycling runs under visible light was also observed. On the basis of the scavengers quenching experiments, PL and EIS determination, the XRD pattern and XPS spectrum of Ag3d in used 4% mpg-C3N4/Ag6Si2O7 hybrid after photocatalytic reaction, the highly efficient photocatalytic performance of 4% mpg-C3N4/Ag6Si2O7 can be clearly elucidated using the mechanism of Z-scheme heterojunction generated between mpg-C3N4 and Ag6Si2O7.

Preparation, Characterization and Visible Light Photocatalytic Activities of Samarium-Doped Mixed Crystalline Phase TiO2 Nanoparticles

Mixed crystalline phase TiO2 nanoparticles with different content of Sm ion were prepared by a facile sol-gel method. The samples were characterized by XRD, XPS, UV-Vis-DRS, and PL. The influence of Sm-doping on structure and visible light photocatalytic activity of mixed phase TiO2 was evaluated by photocatalytic degradation of MB under the irradiation of fluorescent lamp. The results indicate that samarium appears two kinds of Sm3+ and Sm2+ valence state on the surface of TiO2. Sm doping can restrain the phase transition from anatase to rutile, and prevent the grain growth. Appropriate amount of Sm doping and the proportions of rutile and anatase mixed phase can effectively inhibit the recombination of photo-generated electron and hole pairs, expand the wavelength range of absorption spectrum. Moreover, the photocatalytic activity of Sm-TiO2 in MB degradation is evidently enhanced. The MB degradation rate of Sm-TiO2 samples with n(Sm): n(Ti)=0.006 is the best under the irradiation of fluorescent light when the sintered temperature T=500°C, it is 97% within 6 h, which is significantly higher than 56.4% of pure TiO2 under the same experimental conditions.