Preparation of AgBr/DyVO<Subscript>4</Subscript> composite and its excellent photocatalytic activity in RhB degradation under visible light

A AgBr/DyVO₄ composite photocatalyst was synthesized by a hydrothermal method for the first time. The physical and chemical structure and optical properties of the composite catalysts were investigated by XRD, XPS, SEM, TEM and UV–Vis. It was found that the prepared photocatalyst is a ternary composite of DyVO₄, AgBr and Ag. A photodegradation experiment and a cyclic test verified that the composite catalyst has high activity and stability, indicating that the photocatalyst has a wide application potential. The optimal AgBr/DyVO₄ sample can degrade 85% of RhB (20 ppm) under visible light irradiation for 12 min. The degradation rate reaches 0.290 min^?1, which is 14.5 times higher than that of AgBr. The high activity can be ascribed to the coupling effect between AgBr, DyVO₄ and Ag, which leads to high separation efficiency of electrons and holes.     

Dip-coating deposition of resistive BiVO<Subscript>4</Subscript> thin film and evaluation of their photoelectrochemical parameters under distinct sources illumination

Resistive monoclinic bismuth vanadate (BiVO₄) nanocrystals in the form of thin films were obtained by the solution combustion synthesis coupled with the dip-coating deposition process. The structure, morphology, and optical properties of BiVO₄ nanocrystals were characterized by means of x-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis spectroscopy. The photoelectrochemical properties were obtained by cyclic voltammetry and chronoamperometry techniques in potassium chloride (KCl) electrolyte solution under distinct visible light sources irradiation condition. Under blue InGaN light emitting diode (LED) irradiation, the electrode has a better efficiency, faster response time (260 ms), and faster decay time (65 ms), when compared with the irradiation by dichroic lamp. Besides, the photocurrent density (j _ph) is approximately 39 times higher than j _ph obtained under dichroic lamp. The performance analysis based on the methylene blue degradation reaction has shown that the BiVO₄ material has higher electroactivity under InGaN LED irradiation condition, with estimated k _obs value of 200 × 10^?4 min^?1, which is a little higher than the value obtained with dichroic lamp illumination. In the dark condition, the BiVO₄ presented much lower photocatalytic activity.     

Performance of photocatalytic membrane reactor with dual function of microfiltration and organics removal

A nano-structured TiO₂ membrane having desired pore structure has been prepared by the anodization treatment of micro-porous tubular type pure titanium filter. The anodized nano-structured TiO₂ membrane was found to act as photocatalyst and decompose N-nitrosodimethylamine (NDMA) efficiently under UV irradiation. This UV/anodized TiO₂ membrane process realized the complete removal of NDMA with 20 mg L^?1 concentration, indicating that this process can be a promising technology for the purification of NDMA contaminated water.     

Photocatalytic degradation of trichloroethylene on platinum ion-doped TiO<Subscript>2</Subscript> under visible light irradiation

Porous platinum ion-doped TiO₂ (Pt–TiO₂) was prepared by a sol–gel method and demonstrated to have superior photocatalytic activity for the photodegradation of gaseous trichloroethylene (TCE) under visible light (VL) irradiation from a xenon lamp equipped with 422-nm cut-off filter. Kinetic studies were performed to clarify the effect of the doping amounts, space times, VL intensity, and mole fractions of TCE, O₂, and H₂O on the degradation of TCE. Under ultraviolet (UV) irradiation, the photocatalytic activity of Pt–TiO₂ was the same as that of TiO₂, indicating that the doped Pt ion did not act as a recombination center for the photogenerated holes and electrons. Based on the kinetic data and reaction products, we conclude that the photocatalytic degradation of TCE on Pt–TiO₂ under VL irradiation proceeds similarly to TiO₂ under UV irradiation. We also performed the photocatalytic degradation of TCE at the space time of 7.5 × 10⁷ g s mol^?1 in a tubular reactor packed with the Pt–TiO₂ pellets which are more suitable than the Pt–TiO₂ powder for the practical remediation of the contaminated gas. TCE was completely degraded, i.e. 100% conversion was achieved under VL irradiation but only a small quantity of CO₂ was formed with the stoichiometric ratio of [CO₂]_formed/[TCE]_degraded of ca. 0.33. By switching the gas stream containing TCE to humid air, more CO₂ was formed, indicating that the dichloroacetates accumulated on the Pt–TiO₂ surface are photodegradable to CO₂ under VL irradiation.     

Novel Visible-Light-Driven Photocatalyst Co<Subscript>3</Subscript>O<Subscript>4</Subscript>/FeWO<Subscript>4</Subscript> for Efficient Decomposition of Organic Pollutants

A highly efficient and visible light (λ ≥ 420 nm) responsive composite photocatalyst, Co₃O₄/FeWO₄ was prepared by simple impregnation method. The heterojunction semiconductors Co₃O₄/FeWO₄ demonstrated notably high photocatalytic activity over a wide range of composition than the individual component Co₃O₄ or FeWO₄ for the complete degradation of 1,4-dichlorobenzene (DCB) in aqueous phase under visible light irradiation. The photocatalytic activity of composite was optimized at 1/99 Co₃O₄/FeWO₄ composition. After 2 h of visible light irradiation 51% decomposition of 1,4-dichlorobenzene (DCB) was observed utilizing 1/99 Co₃O₄/FeWO₄ photocatalyst while the end members demonstrated a negligible degradation under the same experimental condition. The valence band (VB) and conduction band (CB) of Co₃O₄ is located above the VB and CB of FeWO₄, respectively. Both the semiconductors Co₃O₄ and FeWO₄ exhibit strong absorption over the wide range of visible light. The obviously enhanced photocatalytic performance of Co₃O₄/FeWO₄ composite has been discussed on the hole (h⁺) as well as electron (e^?) transfer mechanism between the VB and CB of individual semiconductors.     

Dimethyl phthalate (DMP) degradation in aqueous solution by gamma-irradiation/H<Subscript>2</Subscript>O<Subscript>2</Subscript>

This work includes the applications of radiation processing to decompose dimethyl phthalate (DMP) with gamma and gamma/H₂O₂ processes. Changes in amounts of DMP, dissolved oxygen, total acidity and formaldehyde with irradiation dose were followed. The qualitative analysis of the DMP and the intermediates were determined by using a gas chromatography combined to mass spectrometry and ion chromatography. The results indicated that degradation rate of DMP was affected by H₂O₂ concentration, irradiation dose and removal efficiency of 25 mg L^?1 DMP can reach 100% for 1.42 kGy irradiation dose in the concentration of 4.8 mM H₂O₂, respectively.     

Synthesis,structural characterization and DNA-binding studies of a new cobalt (II) complex: (HAcr)<Subscript>4</Subscript>[Co(Sal)<Subscript>3</Subscript>]

A new cobalt (II) coordination compound was synthesized using proton transfer mechanism. The reaction between CoCl₂·2H₂O, Salicylic acid (H₂Sal) and acridine (Acr) gave a new coordination compound formulated as (HAcr)₄[Co(Sal)₃], which was characterized by elemental analysis, NMR, IR and UV/Vis spectroscopies. The interaction of this complex with DNA has been investigated in vitro using UV absorption, fluorescence spectroscopy, viscosity measurements and gel electrophoresis methods. The intrinsic binding constant has been estimated to be 5.8 × 10⁵ M^?1 using UV absorption. The interaction of DNA–Co (II) complex caused quenching in fluorescence. The binding constant, the number of binding site and Stern–Volmer quenching constant have been calculated to be 7.7 × 10⁴ M^?1, 1.143 and 1.5 × 10⁴ Lmol^?1, respectively. The increase in the viscosity of DNA with increasing the concentration of the Co (II) complex and the observations of other experiments suggest that the cobalt (II) complex binds to DNA by partial intercalation binding mode. Furthermore, the interaction of DNA–Co (II) complex was confirmed using gel electrophoresis studies. Moreover, molecular docking technique predicted partial intercalation binding mode for the complex.     

Photocatalytic property of surface-modified TiO<Subscript>2</Subscript> nanobelts under visible light irradiation

A novel plasmonic photocatalyst, i.e., acid-etched TiO₂ nanobelts attached with Ag/AgI nanoparticles (NPs) was prepared by deposition–precipitation-photoreduction method. Such surface-modified nanobelts had larger area than the normal one. Ag NPs were formed from AgI by photo-reduction under Xenon lamp irradiation. X-ray diffraction, scanning electron microscopy analysis, UV–Vis diffuse reflectance spectra and fluorescence spectra were used to characterize the structure and optical properties of the sample. The obtained sample exhibited strong photodegradation of methyl orange (MO) under visible light irradiation, which were attributed to both the surface plasmon resonance of Ag NPs and the visible light actived AgI. The photodegradation was accomplished by the transfer of photoexcited electrons from the Ag NPs to the acid-etched TiO₂ nanobelts. After four cycles of photodegradation the photocatalyst was still stable. This novel photocatalyst had a high potential application in wastewater-treatment and biomedical engineering.     

Carbon paste electrode modified with Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles and BMI.PF<Subscript>6</Subscript> ionic liquid for determination of estrone by square-wave voltammetry

A carbon paste electrode (CPE) modified with Fe₃O₄ nanoparticles (Fe₃O₄ NP) and the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (IL BMI.PF₆) was employed for the electroanalytical determination of estrone (E1) by square-wave voltammetry (SWV). At the modified electrode, cyclic voltammograms of E1 in B–R buffer (pH 12.0) showed an adsorption-controlled irreversible oxidation peak at around +0.365 V. The anodic current increased by a factor of five times and the peak potential shifted 65 mV to less positive values compared with the unmodified CPE. Under optimized conditions, the calibration curve obtained showed two linear ranges: from 4.0 to 9.0 μmol L^?1 and from 9.0 to 100.0 μmol L^?1. The limits of detection (LOD) and quantification (LOQ) attained were 0.47 and 4.0 μmol L^?1, respectively. The proposed modified electrode was applied to the determination of E1 in pork meat samples. Data provided by the proposed modified electrode were compared with data obtained by UV–vis spectroscopy. The outstanding performance of the electrochemical device indicates that Fe₃O₄ NP and the IL BMI.PF₆ are promising materials for the preparation of chemically modified electrodes for the determination of E1.     

Synthesis of Na<Subscript>2</Subscript>Ti<Subscript>3</Subscript>O<Subscript>7</Subscript> nanoparticles by sonochemical method for solid state electrolyte applications

Na₂Ti₃O₇ ceramic materials have been widely used in sodium-ion battery applications with relative good results; however, there are still several studies that might be carried out in the improvement of the Na₂Ti₃O₇ properties and the overall batteries’ performance. In this direction, we used sonochemical method following a thermal treatment in order to synthetized pure phase Na₂Ti₃O₇ nanopowders. X-ray diffraction characterization revealed that Na₂Ti₃O₇ is the primary phase in nanopowders and ceramic sample; although, a high level of amorphization was observed in the sonicated nanopowder without heat treatment process. Nanopowder-prepared ceramic sample showed a crystallite size of 50 nm after sintering at 900 °C for 1 h. The specific surface area, pore volume, and pore size were obtained from the B.E.T. measurements, being 51 m² g^?1, 0.07 cm³ g^?1, and 55 Å, respectively. The capacitance values of the nanopowder-prepared ceramic sample were in the order of microfarad. The total energy of the system was used to determine relaxation time of the sample (τ ₀ = 31 ms).     

Folded nanosheet-like Co<Subscript>0.85</Subscript>Se array for overall water splitting

Active, stable, and earth-abundant bifunctional electrocatalyst for overall water splitting is pivotal to actualize large-scale water splitting via electrolysis. In this work, the hierarchical folded nanosheet-like Co_0.85Se array on Ni foam is constructed by liquid-phase chemical conversion with cobalt precursor nanorod array. It can serve as an efficient bifunctional electrocatalyst for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline electrolyte, with a current density of 10 mA cm^?2 at overpotential of 232 mV for OER and 129 mV for HER and Tafel slope of 78.9 mV dec^?1 for OER and 95.0 mV dec^?1 for HER, respectively. The two-electrode alkaline water electrolyzer utilizing this folded nanosheet-like Co_0.85Se array as both anode and cathode toward overall water splitting offered a current of 10 mA cm^?2 at a cell voltage of 1.60 V. This work explores an efficient and low-cost electrocatalyst for overall water splitting application in alkaline electrolytes.     

Photo-fenton refreshable Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>@HCS adsorbent for the elimination of tetracycline hydrochloride

A yolk–shell-structured sphere composed of a superparamagnetic Fe₃O₄ core and a carbon shell (Fe₃O₄@HCS) was etched from Fe₃O₄@SiO₂@carbon by NaOH, which was synthesized through the layer-by-layer coating of Fe₃O₄. This yolk–shell composite has a shell thickness of ca. 27 nm and a high specific surface area of 213.2 m² g^?1. Its performance for the magnetic removal of tetracycline hydrochloride from water was systematically examined. A high equilibrium adsorption capacity of ca. 49.0 mg g^?1 was determined. Moreover, the adsorbent can be regenerated within 10 min through a photo-Fenton reaction. A stable adsorption capacity of 44.3 mg g^?1 with a fluctuation <10% is preserved after 5 consecutive adsorption–degradation cycles, demonstrating its promising application potential in the decontamination of sewage water polluted by antibiotics.     

Enhancement of visible-light photocatalytic activity of Cu-doped TiO<Subscript>2</Subscript> nanoparticles

Bare TiO₂ and Cu-doped TiO₂ nanoparticles with different nominal doping amounts of Cu ranging from of 0.5 to 5.0 mol% were synthesized using the modified sol–gel method. The samples were physically characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller-specific surface area, UV–Vis diffuse reflectance spectroscopy, zeta potential, X-ray photoelectron spectroscopy, inductively coupled plasma, and photoluminescence techniques. The Cu-doped TiO₂ exhibited good photocatalytic activity in mineralization of oxalic acid and formic acid under visible light irradiation. Photomineralization of oxalic and formic acids under visible light irradiation revealed greatly enhanced photoactivity exhibited by the 2.0 mol% Cu-doped TiO₂ photocatalyst compared to bare TiO₂ . The enhanced photocatalytic performance arises from copper ion doping in the TiO₂ structure, leading to an extended photoresponsive range, enhanced photogenerated charge separation, and transportation efficiency.     

Carbon ceramic electrodes modified with mixed oxides SiO<Subscript>2</Subscript>/SnO<Subscript>2</Subscript> for determination of levofloxacin

The preparation of a carbon ceramic electrode modified with SnO₂ (CCE/SnO₂) using tin dibutyl diacetate as precursor was optimized by a 2³ factorial design. The factors analyzed were catalyst (HCl), graphite/organic precursor ratio, and inorganic precursor (dibutyltin diacetate). The statistical treatment of the data showed that only the second-order interaction effect, catalyst × inorganic precursor, was significant at 95% confidence level, for the electrochemical response of the system. The obtained material was characterized by scanning electron microscopy (MEV), X-ray diffraction (XRD), RAMAN spectroscopy, XPS spectra, and voltammetric techniques. From the XPS spectra, it was confirmed the formation of the Si–O–Sn bond by the shift in the binding energy values referred to Sn 3d3/2 due to the interaction of Sn with SiOH species. The incorporation of SnO₂ provided an increment of the electrode response for levofloxacin, with Ipa = 147.0 μA for the ECC and Ipa = 228.8 μA for ECC/SnO₂, indicating that SnO₂ when incorporated into the silica network enhances the electron transfer process. Under the optimized working conditions, the peak current increased linearly with the levofloxacin concentration in the range from 6.21×10^?5 to 6.97×10^?4 mol L^?1 with quantification and detection limits of 3.80×10^?5 mol L^?1 (14.07 mg L^?1) and 1.13×10^?5 mol L^?1 (4.18 mg L^?1), respectively.     

Layered LiNi<Subscript>0.80</Subscript>Co<Subscript>0.15</Subscript>Al<Subscript>0.05</Subscript>O<Subscript>2</Subscript> as cathode material for hybrid Li<Superscript>+</Superscript>/Na<Superscript>+</Superscript> batteries

LiNi_0.80Co_0.15Al_0.05O₂ (NCA) is explored to be applied in a hybrid Li⁺/Na⁺ battery for the first time. The cell is constructed with NCA as the positive electrode, sodium metal as the negative electrode, and 1 M NaClO₄ solution as the electrolyte. It is found that during electrochemical cycling both Na⁺ and Li⁺ ions are reversibly intercalated into/de-intercalated from NCA crystal lattice. The detailed electrochemical process is systematically investigated by inductively coupled plasma-optical emission spectrometry, ex situ X-ray diffraction, scanning electron microscopy, cyclic voltammetry, galvanostatic cycling, and electrochemical impedance spectroscopy. The NCA cathode can deliver initially a high capacity up to 174 mAh g^?1 and 95% coulombic efficiency under 0.1 C (1 C?=?120 mA g^?1) current rate between 1.5–4.1 V. It also shows excellent rate capability that reaches 92 mAh g^?1 at 10 C. Furthermore, this hybrid battery displays superior long-term cycle life with a capacity retention of 81% after 300 cycles in the voltage range from 2.0 to 4.0 V, offering a promising application in energy storage.     

Green fabrication of sandwich-like and dodecahedral C@Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>@C as high-performance anode for lithium-ion batteries

Sandwich-structured C@Fe₃O₄@C hybrids with Fe₃O₄ nanoparticles sandwiched between two conductive carbon layers have attracted more and more attention owing to enhanced synergistic effects for lithium-ion storage. In this work, an environment-friendly procedure is developed for the fabrication of sandwich-like C@Fe₃O₄@C dodecahedrons. Zeolitic imidazolate framework (ZIF-8)-derived carbon dodecahedrons (ZIF-C) are used as the carbon matrix, on which iron precursors are homogeneously grown with the assistance of a polyelectrolyte layer. The subsequent polydopamine (PDA) coating and calcination give rise to the formation of sandwiched ZIF-C@Fe₃O₄@C. When being evaluated as the anode material for lithium-ion batteries, the obtained hybrid manifests a high reversible capacity (1194 mAh g^?1 at 0.05 A g^?1), good high-rate behavior (796 mAh g^?1 at 10 A g^?1), and negligible capacity loss after 120 cycles.     

Physical and photoelectrochemical characterizations of SrWO<Subscript>4</Subscript> prepared by thermal decomposition. Application to the photo electro-oxidation of ibuprofen

We have reported the semi conducting and photoelectrochemical properties of SrWO₄ prepared by chemical route. The phase purity is confirmed by X-ray diffraction and the oxide is characterized by scanning electron microscopy, diffuse reflectance, and electrochemical impedance spectroscopy. SrWO₄ crystallizes in the scheelite structure with an average crystallite size of 378 ± 6 nm. The Raman spectrum gives an intense peak at 920 cm^?1 assigned to A _g mode while the infrared analysis confirms the hexagonal coordination of tungsten. The UV-visible spectroscopy shows an indirect optical transition at 2.60 eV. SrWO₄ exhibits n-type conduction by oxygen deficiency, confirmed by the chrono-amperometry and the intensity potential J(E) curve shows a small hysteresis. The Mott-Schottky plot gives electrons density of 5.72 × 10¹⁸ cm^?3 and a flat band potential of 0.27 V_SCE, indicating that the conduction band derives mainly from W⁶⁺: 6s orbital. The electrochemical impedance spectroscopy (EIS), measured in the range (1–10⁵ Hz), shows the predominance of the bulk contribution with a dark impedance of 38 kΩ cm². As application, the ibuprofen is degraded by electrocatalysis on SrWO₄ with a conversion rate of 42%. An improvement up to 77% has been obtained by electrophotocatalysis under UV light; the conversion follows a first order kinetic with a rate constant of 2.32 × 10^?4 min^?1.     

Photocatalytic effect of nano-TiO<Subscript>2</Subscript> loaded cement on dye decolorization and <Emphasis Type="Italic">Escherichia coli</Emphasis> inactivation under UV irradiation

In the present study, titanium dioxide (TiO₂) nano-particles were synthesized by sol–gel technique and then used to provide nano-TiO₂ loaded cement samples at 1, 5, and 10 wt% for investigation of Malachite green pigment decomposition and Escherichia coli inactivation under UV irradiation. Surveys conducted on the synthesized TiO₂ nano-particles showed a 100 % anatase phase with a mean particle size of 66.5 nm, surface area of 64.352 m² g^?1, and a porosity volume of 0.1278 cm³ g^?1. Cement samples containing this catalyst exhibited stronger photocatalytic properties as compared to the same amount of pure catalyst. Considering both photocatalytic performance and cost of catalyst, 5 wt% titanium dioxide was suggested to be added to cement. By addition of 1 wt% polycarboxylic copolymer as super-plasticizer to the cement paste, the photocatalytic sample activities were reinforced so that a similar performance could be obtained at 1 wt% catalyst as compared to 5 wt% catalyst without super-plasticizer.     

Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/rice husk-based maco-/mesoporous carbon bone nanocomposite as superior high-rate anode for lithium ion battery

Rice husks (RHs), a kind of biowastes, are firstly hydrothermally pretreated by HCl aqueous solution to achieve promising macropores, facilitating subsequently impregnating ferric nitrate and urea aqueous solution, the precursor of Fe₃O₄ nanoparticles. A Fe₃O₄/rice husk-based maco-/mesoporous carbon bone nanocomposite is finally prepared by the high-temperature hydrothermal treatment of the precursor-impregnated pretreated RHs at 600 °C followed by NaOH aqueous solution treatment for dissolving silica and producing mesopores. The macro-/mesopores are able to provide rapid lithium ion-transferring channels and accommodate the volumetric changes of Fe₃O₄ nanoparticles during cycling as well. Besides, the macro-/mesoporous carbon bone can offer rapid electron-transferring channels through directly fluxing electrons between Fe₃O₄ nanoparticles and carbon bone. As a result, this nanocomposite delivers a high initial reversible capacity of 918 mAh g^?1 at 0.2 A g^?1 and a reversible capacity of 681 mAh g^?1 remained after 200 cycles at 1.0 A g^?1. The reversible capacities at high current densities of 5.0 and 10.0 A g^?1 still remain at high values of 463 and 221 mAh g^?1, respectively.     

Advanced Bi<Subscript>2</Subscript>O<Subscript>2.7</Subscript>/Bi<Subscript>2</Subscript>Ti<Subscript>2</Subscript>O<Subscript>7</Subscript> composite film with enhanced visible-light-driven activity for the degradation of organic dyes

Bi₂O_2.7/Bi₂Ti₂O₇ composite photocatalyst films are synthesized by sol–gel dip-coating. The ratio of adding Bi and Ti precursors can be controlled during the preparation process. The phase structure is confirmed by X-ray diffraction. The UV–visible diffuse reflectance spectrum shows that the composite catalysts present light absorption in the visible region. The obtained Bi₂O_2.7/Bi₂Ti₂O₇ composite films possess superior photocatalytic degradation of rhodamine B, owing to the visible light response of Bi₂O_2.7 and the separation of photogenerated electrons and holes between the two components. As a result, the Bi₂O_2.7/Bi₂Ti₂O₇ (Bi/Ti = 1:1) displays the highest photocatalytic activity under visible light or UV light irradiation for the degradation of different organic dyes, including methyl blue, methyl orange and acid orange 7.