Polyacrylamide Gel Method Research Articles

Biochar coupling induced charge transfer switching of a NiAl2O4/NiCr2O4 photocatalyst to enhance photocatalytic degradation of tetracycline hydrochloride

A series of novel (NiAl2O4 (NAO)/NiCr2O4 (NCO)) (S1)/GL heterojunction photocatalysts, denoting as x%GL/S1 (x = 5, 10, 15 and 20), were prepared by the polyacrylamide gel method combined with low temperature sintering technique. Various characterizations confirm that there is special interfacial contact and charge transfer between NAO, NCO and GL. The 10%GL/S1 heterojunction exhibited the best photocatalytic activity and cyclic stability for the degradation of tetracycline hydrochloride (TC). Compared to NAO, NCO and NAO/NCO, the degradation efficiency of 10%GL/S1 was significantly improved, and the degradation percentage reached 83.2% within 30 min. The activity of 10%GL/S1 was studied in relation to catalyst content, drug concentration, pH value, water quality, and co-existing anion. Trapping experiments and free radical verification experiments confirmed that the holes, hydroxyl radicals and superoxide radicals played crucial roles in the photocatalysis process. Possible pathways for TC degradation were studied by HPLC-MS, and the ecotoxicity of TC and its degradation intermediates was evaluated by T.E.S.T. software. The charge transfer and photocatalytic mechanisms confirm that the introduction of GL enhances the interfacial interaction between the components, promotes the carrier migration efficiency, provides a large number of active sites for 10%GL/S1 heterojunction, and produces active free radicals after redox reaction with photoinduced electrons, effectively improving the degradation efficiency of TC.

Synthesis and color-tunable emission of ZnGaOx with different cation ratios by a polyacrylamide gel method

ZnGaOx nanoparticles with varied ratios of Zn2+ to Ga3+ were synthesized by a polyacrylamide gel route. The phase purity and structure are confirmed by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR) and X-ray photoelectron spectrometer (XPS). High crystal quality and elemental distribution are determined by transmission electron microscopy (TEM) measurements. The band gaps of the samples ranging from 3.22 to 4.47 eV are estimated by ultraviolet–visible (UV–Vis) diffuse refectance spectroscopy (DRS). Under the excitation of 325 nm laser light, ZnGaOx nanoparticles with the Zn2+/Ga3+ molar ratios of 0.8:2 and 0.7:2 show two emission peaks at 415 and 510 nm. A marked emission band at 695 nm is observed from the samples with Zn2+/Ga3+ molar ratios of 0.6:2, 0.5:2 and 0.4:2. The luminescence mechanism is discussed based on the experimental results. The luminescence color of as-synthesized samples gradually shifts from blue-green to green-yellow region with decreasing Zn2+/Ga3+ ratio. Interestingly, the sample with Zn2+/Ga3+ ratio of 0.7:2 has the CIE chromaticity coordinates of (x = 0.26, y = 0.33) close to the coordinates (x = 0.33, y = 0.33) of pure white light. Together, ZnGaOx phosphors with different emission colors without doping with rare earths have considerable potential applications in tunable light emitting diodes (LEDs) and color display.

Novel high entropy alloy/NiAl2O4 photocatalysts for the degradation of tetracycline hydrochloride: Heterojunction construction, performance evaluation and mechanistic insights

Novel NiAl2O4 (NAO)/high entropy alloy (HEA) (Ti), NAO/HEA (Mn) and NAO/HEA (Mo) heterojunction photocatalysts with high photocatalytic activity for the degradation of tetracycline hydrochloride (TC) under simulated sunlight irradiation were synthesized by the polyacrylamide gel method combined with a low temperature sintering technique. The effects of environmental parameters, including drug concentration, catalyst content and pH value, on the photocatalytic activity of NAO/HEA photocatalysts were investigated in detail on the basis of the response surface methodology (RSM) and experimental results. The optimal initial TC concentration, catalyst content, and pH were 100 mg/L, 1 g/L, and 5, respectively. The photocatalytic activity of NAO/HEA photocatalyst (84.6 %) was significantly improved compared to the degradation percentage of HEA (Ti) photocatalyst (36.5 %). The roles of active free radicals including h+, •O2−, •OH and oxygen vacancy in photocatalysis were verified using multiple characterization methods. In-depth analysis was conducted on the degradation pathway of TC, the safety of degradation intermediates, and the photocatalytic mechanism of NAO/HEA (Ti) photocatalyst. The Z - scheme heterojunction can significantly improve the transport efficiency of photogenerated carriers and inhibit the recombination rate of electron hole pairs in the system, which provides a new idea for exploring the application of new HEA - based heterojunction photocatalysts in the field of photocatalysis.

Exploring the structural, optical, and dielectric characteristics of polyacrylamide gel synthesized CeMnO3 nanoparticles with Co & Ni ion doping

Nanostructured perovskite materials doped with transition metal ions have attracted significant attention due to their unique electronic and dielectric properties. In this study, we present the synthesis and thorough characterization of cobalt (Co) and nickel (Ni) ion-doped CeMnO3 (CMO) perovskite nanoparticles using a modified polyacrylamide gel method. Our structural analysis suggests that the perovskite phase stabilizes with an orthorhombic phase (Pbnm space group). Morphological analysis conducted via field emission scanning electron microscopy (FESEM) unveils the formation of clustered nanospherical particles. X-ray photoelectron spectroscopy (XPS) reveals mixed oxidation states of Ce, Mn, and Ni ions. Furthermore, UV–Vis and photoluminescence spectra analyses demonstrate a distinctive reduction in band gap and suppressed charge carrier recombination upon doping. The substitution of Ni and Co ions also enhances the screening effect, reducing Coulombic interaction between photoexcited electrons and holes and subsequently increasing the dielectric constant. Analysis of the Cole-Cole plot demonstrates the augmentation of capacitance with Ni substitution. These findings collectively suggest that the decreased dielectric loss and enhanced dielectric constant support the feasibility of these materials for application in storage devices.

Effect of adding silver on photocatalytic properties of ZnAl2O4 nanopowder synthesized using microemulsion and polyacrylamide gel methods for recycled water

In recent decades, water purification and removal of organic pollutants such as organic dyes have been among the most important issues. Photocatalyst is one of the most effective methods for recycled water to eliminate organic pollutants and break them down into safe compounds. One of the most significant factors for determining the efficiency of photocatalyst nanoparticles is the utilization of new synthesis methods. Microemulsion and polyacrylamide gel methods are the two methods that were used for the synthesis of zinc aluminate nanoparticles for this study. The powders obtained from these two synthesis methods were characterized using the X-ray diffraction (XRD) technique, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and ultraviolet–visible spectroscopy (UV–Vis) which were utilized as photocatalysts in the photocatalytic degradation reaction of methylene blue (MB). The results demonstrated that the nanoparticles synthesized in both methods were of single-phase zinc aluminate with a spinel structure. The crystallite size obtained for zinc aluminate synthesized using the microemulsion method was 21.7 nm, whereas, in the polyacrylamide gel method, it was 26.3 nm. Microscopic images represented smaller and more uniform particle sizes in the nanoparticles obtained by the microemulsion method. The band gap energy of zinc aluminate nanoparticles obtained using microemulsion and polyacrylamide gel methods was 4.15 and 3.82 eV, respectively. Similarly, the results of MB removal showed that zinc aluminate nanoparticles synthesized using the microemulsion method and polyacrylamide gel, respectively, were 100% and 71% after 120 min. In the second phase of this study, silver nanoparticles were added to zinc aluminate nanoparticles during the synthesis process. X-ray diffraction showed that silver nanoparticles are formed metallically next to zinc aluminate. Moreover, the addition of silver decreased the crystallite size and slightly increased the band gap energy of zinc aluminate. The results of MB dye degradation tests in the presence of ZnAl2O4–Ag nanocomposites showed that the kinetics of dye degradation increased when the silver increased up to 5 wt%. Finally, the mechanism studied on dye degradation using scavenger agents showed that the main agents of dye degradation are the superoxide radical and the holes created in the valence band. It was consistently confirmed by examining the valence and conduction band potentials and also by comparing these potentials with those responsible for producing superoxide and hydroxyl radicals.

Nano spinel NiAl2O4: structure, optical and photocatalytic performance evaluation and optimization

Four kinds of spinel NiAl2O4 were synthesized by the polyacrylamide gel method using Al2(SO4)3·18H2O and Al(NO3)3·9H2O as aluminum salts and anhydrous NiSO4 and NiSO4·6H2O as nickel salts. The effects of different aluminum salts and nickel salts on the structure, optical and photocatalytic activity of spinel NiAl2O4 were confirmed by various characterizations. There is no NiO impurity in the spinel NiAl2O4 synthesized with Al2(SO4)3·18H2O as aluminum salt, while NiAl2O4, NiO and C–O functional group coexist in the target product with Al(NO3)3·9H2O as aluminum salt, and C–O functional group and NiO inhibits the photocatalytic activity of the system. Based on photocatalytic experiment, response surface methodology and free radical verification experiment, the influence of experimental parameters including synthesis pathway, initial drug concentration, initial pH and catalyst content on the photocatalytic activity of spinel NiAl2O4 and the main active species involved in the reaction were investigated. The degradation percentage of spinel NiAl2O4 synthesized with Al2(SO4)3·18H2O as aluminum salt and NiSO4·6H2O as nickel salt was 86.3% at the initial concentration of 50 mg l−1, pH = 5.33 and catalyst content of 1 g l−1. The mechanism investigation confirmed that the C–O functional group plays the dual role of impurity level and electron transfer in the degradation of tetracycline hydrochloride by spinel NiAl2O4.

Polyacrylamide gel synthesis of Ni1-xCuxAl2O4 nano-pigments with photocatalytic properties

Ni1-xCuxAl2O4 (x = 0, 0.25, 0.50, 0.75, and 1) nanoparticles were prepared via a polyacrylamide gel method. The compounds were characterized by Fourier Transform infrared spectroscopy, thermal analysis, X-ray diffraction, UV–vis diffuse reflectance, and scanning electron microscopy. The produced powders were studied for dual applications of pigment and photocatalyst. The results showed that a spinal structure with an average particle size of 70 nm was obtained via this polymer-assisted synthesis method. The substitution of copper in the structure of nickel aluminate caused an increase in crystallite size growth, whereas it decreased the band gap energy of the samples. DRS results demonstrated that the band gap energy of Ni1-xCuxAl2O4 with x = 0 reduced from 3.4 eV to 2.51 eV for the sample with x = 0.75. The CIE colorimetric values of the samples showed that the color of the nanoparticles changed from cyan for x = 0 to brown for x = 0.75. The photocatalytic investigations revealed that all the produced powders can effectively remove methylene blue pollution from water.

Facile synthesis of high-entropy (Co0.2Cr0.2Fe0.2Mn0.2Ni0.2)3O4 nanopowders and their electrochemical properties as supercapacitor electrode

High-entropy oxide (HEO) nanopowders are expected to have unique electrochemical energy storage properties due to their unique structural characteristic and tailorable chemical composition. However, HEO nanopowders are difficult to be prepared because of severe grain coarsening and particle agglomeration in high temperature calcination. In this study, a polyacrylamide gel method was presented to prepare high-entropy (Co0.2Cr0.2Fe0.2Mn0.2Ni0.2)3O4 nanopowders. The mole ratio of acrylamide/metal cations (A/M) had a significant influence on the average particle size of HEO nanopowder, which was decreased with the increase of A/M mole ratio. Electrochemical tests demonstrated that as-prepared HEO nanopowders had a specific capacitance of 384 F/g at a current density of 1 A/g, which was remained 57 % as the current density was increased to 20 A/g. Furthermore, a relatively high capacitance retention of 60 % was obtained after 2000 charge-discharge cycles at 5 A/g. In addition, a HEO//activated carbon asymmetric supercapacitor was assembled, which achieved an energy density of 24 Wh/kg at a power density of 746 W/kg. This study presents a simple and cost-effective method to prepare HEO electrode material for supercapacitors.

A and B sites doped CaAl12O19: Phase component, energy band, color and photoluminescence tuning, color performance prediction and application for pigments

The polyacrylamide gel method was used to fabricate the Ca1-xCoxAl12O19, Ca1-xNixAl12O19, CaAl12-xInxO19 and CaAl12-xWxO19 (x = 0–0.5) pigments. The phase compositions, energy bands, color and photoluminescence properties of the pigments can be controlled by adjusting the type and content of doping ions. The color of CaAl12O19 changed from white to blue with the Co2+ ion doping, from white to gray green with the Ni2+ ion doping, and from white to bright white with the In3+ and W6+ ions doping. The genetic algorithm optimized back propagation neural network can predict the color properties of CaAl12O19 based pigments. The application of the pigments shows that they can be used in painting, coating and other fields. The Co2+ and Ni2+ doped CaAl12O19 exhibits high blue emission, while In3+ and W6+ doped CaAl12O19 shows strong green emission and the luminescence is highly dependent on the type and content of dopant ion, phase composition and energy transfer.

BaTiO3/CeO2 heterojunction photocatalysts: design, construction and a novel application for the photocatalytic degradation of oxytetracycline hydrochloride

Abstract A polyacrylamide gel method combined with low temperature calcination technology has been developed to synthesize the BaTiO3/CeO2 heterojunction photocatalysts, which were formed by hybriding the large BaTiO3 particles and fine CeO2 nanoparticles with varied mass percent of CeO2. Various characterization methods have been used to determine the phase structure, functional group information, elemental composition, microstructure, optical and photocatalytic activity of BaTiO3/CeO2 heterojunction photocatalysts. The introduction of CeO2 into the host lattice of BaTiO3 does not change the optical band gap value (Eg = 3.20 eV) of the host lattice. As expected, the BaTiO3/CeO2 heterojunction photocatalysts exhibit highly enhanced and CeO2 composition-dependent photocatalytic activity for the degradation of oxytetracycline hydrochloride under simulated sunlight irradiation. The BaTiO3/5 wt% CeO2, BaTiO3/10 wt% CeO2, and BaTiO3/15 wt% CeO2 showed lower photocatalytic activity, while BaTiO3/20 wt% CeO2 showed highest photocatalytic activity (96.89 %) over the single component BaTiO3 and CeO2 photocatalysts with the initial oxytetracycline hydrochloride concentration, photocatalyst content and irradiation time were 100 mg/L, 1.5 g/L and 120 min, respectively. The enhanced photocatalytic activity of BaTiO3/20 wt% CeO2 heterojunction photocatalysts is ascribed to the cooperation between Ce3+ and Ce4+, improved charge transfer and separation of electron-hole pairs generated on irradiation with simulated sunlight and proper amount of surface defects or oxygen vacancies on the BaTiO3/CeO2 heterojunction photocatalysts.

Characterization and photocatalytic activity of CoCr2O4/g-C3N4 nanocomposite for water treatment.

One of the materials that has recently been used to remove environmental pollution from industrial effluents with photocatalytic technology is cobalt chromate (CoCr2O4) nanoparticles. An effective way to improve the photocatalytic properties of materials is to composite them with other photocatalysts to prevent recombination of electron-holes and accelerate the transfer of oxidation/reduction agents. Graphitic carbon nitride (g-C3N4) is an excellent choice due to its unique properties. In this research, CoCr2O4 and its composite with g-C3N4 (5, 10, and 15%) were synthesized by polyacrylamide gel method and characterized by X-ray diffraction, scanning electron microscopy, FTIR, UV-Vis spectroscopy techniques. The photocatalytic behavior of synthesized nanoparticles was investigated in the degradation process of methylene blue dye. The results showed that the composite samples have higher efficiency in photocatalytic activity than the pure CoCr2O4 sample. Using CoCr2O4-15 wt%g-C3N4 nanocomposite, after 80min, methylene blue was completely degraded. The mechanism of degradation by CoCr2O4-g-C3N4 nanocomposite was the superoxide radical produced by the reaction of electrons with oxygen absorbed on the catalyst surface, as well as optically produced holes directly.

Removal of Congo Red from Wastewater Using ZnO/MgO Nanocomposites as Adsorbents: Equilibrium Isotherm Analyses, Kinetics and Thermodynamic Studies

One step polyacrylamide gel method was used to synthesize the ZnO/MgO adsorbents and the adsorption behavior with Congo red (CR) from wastewater was extensively investigated. Various advanced techniques were applied to confirm the ZnO/MgO adsorbents consist of Zn, C, Mg and O elements and do not contain any other impurity elements. With the increase of MgO content, the morphology of ZnO/MgO adsorbent changes from the agglomeration of large particles to evenly dispersed fine particles and then to icicle structure. Results demonstrated that the adsorption process of ZnO/MgO adsorbents was significantly affected by the change in initial dye solution pH, initial adsorbent dosage, contact time and reaction temperature. The optimum pH, adsorbent dosage, contact time and reaction temperature is 9.81, 2 g /L, 65 min and 293 K, respectively. The maximum adsorption capacity of ZnO/MgO (nZnO:nMgO = 8:2) adsorbents (295.138 mg/g) for the adsorption of CR dye was approximately double that of previous reports (125 mg/g). The adsorption equilibrium data are well fitted by the Freundlich and Langmuir isotherm models. Thermodynamic studies indicate that the adsorption process of ZnO/MgO adsorbents is an exothermic process. Based on the experimental and theoretical analysis, the adsorption mechanism for the ZnO/MgO adsorbents consisted of hydrogen bonding, n-π interaction and electrostatic interaction. The present work pioneers the potential application of ZnO/MgO adsorbents for the adsorption of CR dye and further provides experimental evidence for the synthesis of other adsorbents.

Facile synthesis of high-entropy zirconate nanopowders and their sintering behaviors

The challenge in synthesizing high-entropy ceramic (HEC) nanopowders is to suppress severe grain coarsening and particle agglomeration, which occur at elevated temperatures. This challenge could be addressed by the polyacrylamide gel method. In this work, single-phase high-entropy (La_0.2Nd_0.2Sm_0.2Gd_0.2Yb_0.2)₂Zr₂O₇ and (La_0.2Nd_0.2Y_0.2Eu_0.2Gd_0.2)₂Zr₂O₇ nanopowders without agglomeration were successfully synthesized using the polyacrylamide gel method for the first time. The results showed that phase composition, particle size, and agglomeration degree of the nanopowders were greatly influenced by the molar ratio of acrylamide (AM)/Zr and calcination temperature. These as-synthesized high-entropy zirconate (HEZ) nanopowders could be sintered into fully dense ceramics at 1500 ℃ for 2 h. These HEZ nanopowders showed a phase transformation from a defect-fluorite phase to a pyrochlore phase with the increase of sintering temperature. Additionally, two-step sintering of these nanopowders was conducted, and the HEZ ceramics with fine grains were prepared. The polyacrylamide gel method is simple and easily operated, which is a facile approach of producing the HEC nanopowders with excellent sinterability.

Enhanced photocatalytic degradation of 4-nitrophenol using polyacrylamide assisted Ce-doped YMnO3 nanoparticles

This research article mainly reports on the precise structural, optical, and photocatalytic properties of cerium (Ce)-substituted yttrium manganite (YMnO3) nanoparticles synthesized by the polyacrylamide gel method. The characteristics of YMnO3 were investigated by the substitution of Ce into the Y site at various molar percentages. The Raman and X-ray diffraction (XRD) analyses confirmed the pure phase of hexagonal YMnO3, supported by the Rietveld refinement. The microstructural studies indicate inhomogeneous and irregular particle distribution. The X-ray photoelectron spectroscopy (XPS) results show the presence of two ionic states of Mn and Ce along with Y3+ state and oxygen vacancies. Extensive optical exploration using photoluminescence (PL) spectroscopy and UV–Vis–NIR analysis indicates that the intensity of absorption peak increases in the visible region, while the bandgap decreases from 1.42 to 1.30 eV with the Ce ion doping (5 mol%–15 mol%). Photocatalytic properties of the polycrystalline nanoparticles were investigated by degradation of the pollutant 4-nitrophenol. The process of amplified photocatalysis process was elucidated by the lowered bandgap and rate of charge carrier recombination. It can be conjugated from this study that the synthesized nanoparticles may be employed as highly efficient (92.8%) visible light-triggered photocatalysts in a variety of real-world applications.

Strontium-induced phase, energy band and microstructure regulation in Ba1−xSrxTiO3photocatalysts for boosting visible-light photocatalytic activity

The polyacrylamide gel method has been developed for fabrication of Ba1−xSrxTiO3(BST) photocatalysts. The structure, surface morphology, band gap and photocatalytic activity of BST photocatalysts can be regulated by adjusting thexvalue.

Visible-light-enhanced photocatalytic activity of BaTiO3/γ-Al2O3 composite photocatalysts for photodegradation of tetracycline hydrochloride

A polyacrylamide gel method combined with low temperature sintering technology was developed for fabrication of BaTiO3/γ-Al2O3 composite photocatalysts, which exhibits excellent photocatalytic activity for the degradation of tetracycline hydrochloride (TC-HCl) under simulated sunlight irradiation. The effects of BaTiO3/γ-Al2O3 mass percentages, drug concentrations and pH values on the photocatalytic activity of BaTiO3/γ-Al2O3 composite photocatalysts were investigated. The optimum BaTiO3/γ-Al2O3 mass percentage, drug concentration and pH value are 5 wt%, 50 mg/L, and 6.77, respectively. The maximum photocatalytic degradation rate of BaTiO3/(5 wt%) γ-Al2O3 composite photocatalysts for the degradation of TC-HCl was approximately 16.81 times that of γ-Al2O3. The trapping experiments and reactive oxygen species production experiments proved that reactive hole and hydroxyl radical played major role in drug degradation. The photocatalytic activity enhancement of the BaTiO3/γ-Al2O3 composite photocatalysts came from the defect states in alumina and the interfacial defects between barium titanate and alumina and the high charge transfer and separation efficiency, which resulted from the type II band arrangement structure of BaTiO3/γ-Al2O3. The above results reveal that there is a significant potential application for the BaTiO3/γ-Al2O3 composite as a photocatalyst in the photo-degradation of drugs under simulated sunlight irradiation.

Selective removal of antibiotics over MgAl2O4/C3N4/YMnO3 photocatalysts: Performance prediction and mechanism insight

AbstractA simple polyacrylamide gel method combined with low temperature sintering technology has been used to synthesize the C–O functional groups grafted MgAl2O4/C3N4/YMnO3 (MAO–CN–YMO) heterojunction photocatalysts with enhanced visible‐light‐induced photodegradation toward oxytetracycline hydrochloride (OTC‐HCl). A variety of characterization methods are used to gain insight into the phase purity, crystal structure, microstructure, functional group information, elemental composition, surface defect, light response capability, and photocatalytic activity of the as‐synthesized samples. The influences of the mass ratios of mCN/mYMO, mCN/mMAO, and mMAO/(mCN + mYMO) in CN–YMO, CN–MAO, and MAO–CN–YMO heterojunction photocatalysts on the photocatalytic activity for the degradation of OTC‐HCl was also discussed, and the optimal mass ratio of mMAO/(mCN + mYMO) is identified as 15 wt%. The photocatalytic experiments confirmed that the MAO–CN–YMO heterojunction photocatalysts had high selectivity for the degradation of antibiotics. The prediction of the photocatalytic activity of the MAO–CN–YMO heterojunction photocatalysts for the degradation of OTC‐HCl was made by a variety of intelligent algorithm models. The results of the whale optimization algorithm are highly consistent with the experimental results. Combined with the energy band theory and the characterization results of high‐performance liquid chromatography–tandem mass spectrometry, the free radicals in the reaction solution preferentially attacked the –CH3, –NCH2, and –OH of OTC‐HCl during the degradation of OTC‐HCl by MAO–CN–YMO heterostructure photocatalysts, and then attack –C=O and –C=O–NH2, and finally perform ring‐opening reaction to degrade OTC‐HCl into nontoxic and harmless products of small molecules such as CO2, H2O, and NH4+. This work provides a new idea for the development of novel double p–n junction MAO–CN–YMO heterojunction photocatalysts for antibiotic degradation and the prediction of photocatalytic activity of multiple heterojunction photocatalysts by intelligent algorithms.

Synthesis and Characterization of BaTiO3/TiO2 Heterojunction Photocatalyst for Novel Application in Photocatalytic Degradation of TBBPA under Simulated Sunlight Irradiation

AbstractThe polyacrylamide gel method combined with low temperature sintering technology (PGMCLTST) have been used to synthesize the BaTiO3/TiO2 heterojunction photocatalysts. The BaTiO3/TiO2 heterojunction photocatalyst only contains tetragonal BaTiO3, rutile TiO2 and anatase TiO2, without any other impurities. Based on a variety of characterization, it was confirmed that a special heterojunction was formed between BaTiO3 and TiO2, and there were a large number of interface defects or oxygen defects in the samples. The BaTiO3/10 wt % TiO2 heterojunction photocatalysts have high photocatalytic activity for the degradation of tetrabromobisphenol A (TBBPA) under simulated sunlight irradiation. The interfacial defects enhance the transfer and separation efficiency of charge carriers in BaTiO3/TiO2 heterojunction photocatalysts. This technique provides a new idea for the application of BaTiO3/TiO2 heterojunction photocatalysts and other heterojunction photocatalysts in the degradation of persistent organic pollutants (POPs).

Double heterojunction CQDs/CeO2/BaFe12O19 magnetic separation photocatalysts: Construction, structural characterization, dye and POPs removal, and the interrelationships between magnetism and photocatalysis

This novel double heterojunction carbon quantum dots (CQDs)/CeO2/BaFe12O19 magnetic separation photocatalysts (CCBFOMSPs) were successfully prepared via a polyacrylamide gel method and low temperature sintering technology combined with a hydrothermal method. The CQDs components in CCBFOMSPs were identified by neutron powder diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy. The charge carriers could transfer and separation between the valence state components (CeO2 and BaFe12O19) and CQDs facilely, inhibiting the recombination of electron-hole pairs significantly by Hall effect. The photocatalytic activity of CCBFOMSPs for the degradation of mixed dyes include methyl orange (MO), rhodamine B (RhB) and methylene blue (MB) and tetrabromobisphenol A (TBBPA) were remarkably improved by regulating the electromagnetic interaction between the BaFe12O19 contents and the photo-generated electrons. Capturing experiment showed that the active species of hole (hVB+), hydroxyl radical (•OH) and superoxide radical (•O2−) played dominant roles in mixed dyes degradation. Attractively, the effect shed new light on wide applications of the double heterojunction magnetic separation photocatalysts.

A simple fabrication, microstructure, optical, photoluminescence and supercapacitive performances of MgMoO4/MgWO4 heterojunction micro/nanocomposites

A polyacrylamide gel method combined with low temperature calcination technology are used to synthesize the MgMoO4/MgWO4 micro/nanocomposites. MgMoO4 and MgWO4 were coupled to form a special heterojunction structure with (220) and (111) crystal planes. Microstructural analysis confirmed that the MgMoO4/MgWO4 micro/nanocomposites were composed of large flake particles and small nanoparticles. MgMoO4/MgWO4 heterojunction micro/nanocomposites could not change the optical band gap (Eg) value of MgMoO4 but enhanced the concentration of adsorbed oxygen in the system. Electrochemical performance analysis showed that the specific capacitance of MgMoO4/20 wt %MgWO4 micro/nanocomposites is 222 mA h g−1. The supercapacitor performance of MgMoO4/MgWO4 heterojunction micro/nanocomposites depends strongly on the preparation method, element composition, specific surface area and the transfer and separation efficiency of charge carriers. Photoluminescence analysis shows that the MgMoO4/MgWO4 micro/nanocomposites exhibits a stronger emission peak than MgMoO4 at 524 nm due to the synergistic effect of the adsorbed oxygen concentration and the recombination rate of charge carriers.