UV Vis Diffuse Reflectance Spectroscopy Research Articles

Structural study and photocatalytic activity of BiMeVOx materials[formula omitted

We focused on the synthesis of copper and tantalum doped bismuth vanadate and on its photocatalytic activity. The solid-state reaction is used to synthesize Bi4V2 - xCux2Tax2O11 -3x4 where Cu2+ and Ta5+ replace the vanadium (V5+) in the in perovskite-like layers. The phase transformation from α to γ is determined by X-ray diffraction and Fourier transform infrared spectroscopy. This transformation is due to the incorporation of Cu2+ and Ta5+ in the Bi4V2O11 lattice. Scanning electron microscopy was used to investigate the morphology, and elemental compositions of the synthesized photocatalysts. The bandgap energies of BiCuTaVOx are between 2.00 and 2.10 eV, they have been determined by using UV–visible diffuse reflectance spectroscopy. How the rate of substitution between Cu2+ and Ta5+ affects photocatalytic activity was investigated. The impact of the substitutions simple and double by copper and tantalum, was then examined for Bi4V1.7Cu0.3O10.55, Bi4V1.7Ta0.3O11, and Bi4V1.7(Cu-Ta)0.3O10.775. Copper and tantalum play a synergic effect on photodegradation of Sulfamethoxazole. The effect of physical factors including the catalyst amount and pH on the photocatalytic degradation under UV–visible was studied. However, Bi4V1.7Cu0.15Ta0.15O10.775 also exhibits a photocatalytic activity under visible light irradiation using 0.8 g/l of photocatalyst at pH10. The degradation reaches 65 % in the optimal conditions under visible light irradiation during 5 h.

High performance NaNbO3/CdS/Bi2S3 ternary heterostructured photoelectrocatalysts for efficient OER activity

CdS and Bi2S3 decorated NaNbO3 samples were prepared by hydrothermal and linker assisted combinatory approach using oleic acid and starch as surface capping agents. Successful deposition of small sized and high surface area CdS and Bi2S3 over the smooth surface of large sized NaNbO3 was carried out. To prepare heterostructures of NaNbO3 different weight ratios of CdS and Bi2S3 were employed. The as-prepared heterostructures were subsequently characterized by X-ray diffraction (XRD), UV–visible diffused reflectance spectroscopy (DRS), Field Emission Scanning Electron Microscopy (FESEM), Brauner-Emmette-Teller (BET) surface area studies, and X-ray Photoelectron spectroscopy (XPS) studies. As-developed heterostructures were investigated as photoelectrocatalysts (PEC) for oxygen evolution reaction (OER) from water splitting reaction. From PEC OER investigations, it was observed that heterostructured sample (HS-2) with 10 wt % CdS and 5 wt% Bi2S3 show efficient and enhanced PEC OER activity as compared to the pristine parent compounds. The maximum current density of 11.9 mA/cm2 with low onset potential of 0.89 V and low tafel slope of 107 mV/day was observed in HS-2 sample under white light illumination. The efficient and enhanced activity was attributed to red shift in the absorption of NaNbO3 sample and efficient charge separation taking place due to deposition of CdS and Bi2S3 over the surface of NaNbO3.

Enhanced visible light photocatalytic degradation of dyes by the oxygen-rich vacancy-assisted S-scheme heterojunction Al2O3/BiOBr: Catalytic mechanism and performance evaluation

A heterojunction Al2O3/BiOBr composite photocatalyst, characterized by an S-scheme structure and enriched with oxygen vacancies, was synthesized through a solvothermal reaction coupled with an in situ growth approach. Oxygen vacancies on the catalyst surface, enhanced by the robust coupling between Al2O3 and BiOBr, were corroborated by X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). Techniques such as UV–vis diffuse reflectance spectroscopy (DRS), UV photoelectron spectroscopy (UPS), Mott–Schottky characterization, and experimental radical trapping experiments collectively validated the pathways for migrating photogenerated carriers. The interplay between the surface oxygen vacancies and the S-scheme Al2O3/BiOBr heterojunction, which possesses potent redox capabilities, significantly improved the photocatalytic degradation. This enhancement was particularly evident in the outstanding visible photocatalytic degradation performance against rhodamine B (RhB), methyl orange (MO), and basic fuchsin (BF). The synthesized composite photocatalysts demonstrated 92% retention of degradation efficiency after five recycling cycles, indicating their considerable stability.

Synthesis and Exploration of Barium Stannate-Zirconate BaSn1-xZrxO3 (0 ≤ X ≤ 1) Solid Solutions as Photocatalysts.

Employing ionic liquid-assisted microwave synthesis and moderate heat treatment allows for the preparation of otherwise difficult-to-obtain perovskite-type BaSn1-xZrxO3 solid solutions (0 ≤ x ≤ 1). The impact of substituting Sn for the crystal structure, crystallinity, morphology, and photocatalytic performance was investigated. The obtained materials are characterized by X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller (BET) surface area analysis, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, and Raman and IR spectroscopy. SEM images show that the morphology of the samples varies from rods for x = 0, 0.2 to spherical for x = 0.5, 0.8, 1. Upon Zr for Sn substitution, the band gap changes from 3.1 to 5.0 eV as the valence and conduction bands move to lower and higher energies. The photocatalytic activities of the BaSn1-xZrxO3 samples in the hydroxylation of terephthalic acid (TA) follow the order BaSn0.5Zr0.5O3> BaSn0.8Zr0.2O3> BaSnO3> BaSn0.2Zr0.8O3> BaZrO3. The superior photocatalytic activity of BaSn0.5Zr0.5O3 can be attributed to the synergistically favorable combination of a suitable band structure, band gap size, and increased surface area-to-volume ratio, resulting in a diminished crystalline particle size unattainable from samples prepared via traditional synthetic routes or without ionic liquid.

Preparation and Properties of Cotton Fabric Photocatalyzed by Ag-Doped Madder-Sensitized TiO2

In this study silver nanoparticles (NP) were grown in-situ on the surface of madder-sensitized TiO2 by an in-situ reduction method using silver nitrate as a silver source and a honeysuckle extract as a reducing agent. Silver doped madder-sensitized TiO2 nanoparticles were then prepared, supported on the surface of cotton fabrics to prepare photocatalytic cotton fabrics with high-efficiency self-cleaning properties and excellent antibacterial properties. transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analyses showed that elemental Ag NPs were deposited on the surface of the madder-sensitized TiO2, and that Ag-doped madder-sensitized TiO2 NPs were successfully loaded on the cotton fabric surface. The results of UV-Visible diffuse reflectance spectroscopy (UV-Vis-DRS) and Photoluminescence Spectroscopy (PL) showed that Ag-doping could further reduce the band gap of madder-sensitized TiO2 than pure TiO2. The absorption of light in the photocatalytic system was increased, and the recombination of electron-hole pairs was effectively inhibited. Compared with madder-sensitized TiO2 photocatalyzed cotton fabric, the degradation rate of nano-Ag-doped madder-sensitized TiO2 photocatalytic cotton fabric for methylene blue (MB) was increased by 10.66% within 2 h, and the degradation process was in line with the first-order reaction kinetic model. After 5 times of washing, the photocatalytic cotton fabric still had excellent photocatalytic performance. Its antibacterial rates against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) reached 100 and 99.99%, respectively. In addition, it had good wrinkle resistance and UV protection properties, but the cross-linking modification reduced the breaking strength by about 14%.

Microwave-Assisted Synthesis of Flower-like MnMoO4 Nanostructures and Their Photocatalytic Performance.

This article describes an affordable method for the synthesis of MnMoO4 nanoflowers through the microwave synthesis approach. By manipulating the reaction parameters like solvent, pH, microwave power, and irradiation duration along this pathway, various nanostructures can be acquired. The synthesized nanoflowers were analyzed by using a powder X-ray diffractometer (XRD), field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), and UV-vis diffuse reflectance spectroscopy (UV-DRS) to determine their crystalline nature, morphological and functional group, and optical properties, respectively. X-ray photoelectron spectroscopy (XPS) was performed for the examination of elemental composition and chemical states by qualitative and quantitative analysis. The results of the investigations demonstrated that the MnMoO4 nanostructures with good crystallinity and distinct shape were formed successfully. The synthesized MnMoO4 nanoflowers were tested for their efficiency as a photocatalyst in the degradation studies of methylene blue (MB) as model organic contaminants in an aqueous medium under visible light, which showed their photocatalytic activity with a degradation of 85%. Through the band position calculations using the electronegative value of MnMoO4, the photocatalytic mechanism of the nanostructures was proposed. The results indicated that the effective charge separation, and transfer mechanisms, in addition to the flower-like shape, were responsible for the photocatalytic performance. The stability of the recovered photocatalyst was examined through its recyclability in the degradation of MB. Leveraging MnMoO4's photocatalytic properties, future studies may focus on scaling up these processes for practical and large-scale environmental remediation.

Carbon based cobalt titanate perovskite nanocomposite: Synthesis, characterization, and excellent visible light driven photocatalytic performance

Titanium-based perovskite oxides are the promising photocatalysts for an efficient degradation of organic pollutants. However, charge carriers recombination and wide band gap energy are still the main challenges in their visible-light-driven photocatalytic applications of Titanate perovskites, ATiO3. The immobilization of Titanium-based perovskites on a carbonaceous substrate such as nitrogen-rich carbon nitride, can be considered as an excellent option for enhancing photocatalytic performance. Here, the CoTiO3/C3N5 nanocomposite was synthesized by simple reflux method and used for photocatalytic degradation of three organic pollutants including methylene blue (MB), tetracycline hydrochloride (TC), and bisphenol A (BPA). The results indicated that the photocatalytic activity of the CoTiO3 perovskite was considerably improved by introducing C3N5 nanosheets and fabricating CoTP/C3N5 nanocomposite. The crystalline structure of CoTiO3/C3N5 (CoTP/C3N5) nanocomposites was confirmed successfully by XRD analysis. The specific surface area of the synthesized CoTP/C3N5 nanocomposite was 8.15 m2/g calculated by N2 adsorption–desorption technology. In the 60th minute of the photocatalytic process, the degradation efficiency of MB, TC, and BPA by CoTP/C3N5 were obtained as 98.70, 60.33, and 92.90 %, respectively, which were higher than pristine CoTiO3 nanorods and C3N5 nanosheets. Electrochemical impedance analysis shows that the CoTP/C3N5 nanocomposite has good electrochemical performance. The improvement photocatalytic activity CoTP/C3N5 can be attributed to the suppressing the recombination of photogenerated electrons and holes and good electrochemical performance with high electron transfer capability. The results achieved from UV–Visible Diffused Reflectance Spectroscopy (DRS), mott-schottky measurements and the photocatalytic degradation experiments in the presence of scavengers confirmed the significantly accelerating the Z-scheme charge transfer mechanism where photoexcited carriers can migrate between CoTiO3 perovskite and C3N5 nanosheets.

Photoelectrochemical sensor based on Sn3O4/CdS heterojunction for detecting glucose in the body and Cu(Ⅱ) ion

In this work, photoactive composites of Sn3O4/CdS at different ratios were synthesized by a solvothermal method. First, Sn3O4 was synthesized. To further improve its photoelectric performance, Sn3O4/CdS-X(X = n(Sn3O4)/n(CdS)) with different molar ratios were synthesized by solvothermal method. The composition, surface structure, valence state and optical properties of Sn3O4/CdS-X were studied by a series of characterization methods. The test results show that Sn3O4/CdS-X have better photoelectric performance than Sn3O4 and CdS. UV–visible diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence (PL) demonstrate Sn3O4/CdS-0.55 exhibits the broadest visible light absorption range (360 ∼ 540 nm) and the strongest ability of photogenerated carrier separation. Based on the above performance advantages, Sn3O4/CdS-0.55 was opted to construct the PEC sensor for glucose and Cu(Ⅱ) ion. The linear range for detecting glucose is 0.5 µM-40 mM, and the LOD is 0.067 µM (S/N = 3). For Cu(Ⅱ) ion, these values are 1–290 µM and 0.066 µM, respectively. Moreover, the sensor shows superior selectivity, stability, and reproducibility, which can be used to detect actual samples.

Nickel-containing catalysts for ethylene conversion to motor fuel components and light alkenes

Polyfunctional Ni-containing catalysts supported on the B2O3-Al2O3 and MoO3-Al2O3 were prepared by a sequential impregnation. They were evaluated in ethylene conversion to C5+ alkenes or propylene. The catalysts were characterized by X-ray diffraction, Fourier transformed infrared spectroscopy, Fourier transformed infrared spectroscopy of adsorbed CO, UV-VIS diffuse reflectance spectroscopy, temperature programmed reduction and temperature-programmed desorption of NH3. NiO/B2O3-Al2O3 samples containing Ni2+ cations chemically bonded to the acid support are the most effective catalysts for ethylene oligomerization. The NiO/MoO3-Al2O3 catalyst activity in the ethylene conversion to propylene is related with the presence of ethylene dimerization active sites, i.e. Ni2+ cations bonded to the support acidic sites, and active sites of metathesis in the form of monomolybdate species.

Construction of novel Ru-embedded bulk g-C3N4 photocatalysts toward efficient and sustainable photocatalytic hydrogen production

Novel Ru-embedded bulk graphitic carbon nitride (g-C3N4) photocatalysts containing different wt% of Ru (0.5–2 % wt) were synthesized by a simple mixing method of ruthenium complex with g-C3N4. The photocatalytic activity of the synthesized photocatalysts was assessed for hydrogen production in an aqueous solution containing methanol with and without Pt. The optimal hydrogen production rate of the most active photocatalyst (0.8 % Ru/CN) was 246 μmol/h without Pt and 1021 μmol/h with Pt, which was more than two times higher than pure g-C3N4. Various physiochemical techniques such as X-ray diffraction (XRD), N2 adsorption-desorption isotherms, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV–vis DRS), photoluminescence spectroscopy (PL) and transition photocurrent response (PC) were applied to investigate the origin of activity of the Rux/CN photocatalysts. Results indicated that the loading of g-C3N4 with Ru nanoparticles enlarged its surface area and enhanced visible light absorption. Importantly, Ru nanoparticles promoted the charge carrier separation and transfer efficiency of g-C3N4 revealed by the PL and PC measurements, enhancing the photocatalytic activity of the embedded photocatalyst. Furthermore, XPS proved the existence of Ru (II) of RuO2 and metallic Ru0. The Ru-embedded g-C3N4 showed high photocatalytic activity, which makes them attractive materials for further applications in photocatalysis.

Inclusion complexes of cucurbit[n]urils (n = 7, 8) with η5‐cyclopentadienyl methyl tricarbonyl molybdenum(II) and their use in epoxidation catalysis

There are very few known examples of supramolecular compounds comprising molybdenum species hosted inside the portals/cavities of cucurbit[n]urils (CBn). In this work, CB7 and CB8 macrocycles have been studied as hosts for the carbonyl complex [CpMo(CO)3Me] (1) (Cp = η5‐C5H5). Compounds were isolated in the solid state and characterized as genuine 1:1 inclusion complexes (1@CBn) by elemental and thermogravimetric analyses, powder X‐ray diffraction, scanning electron microscopy, 13C{1H} cross‐polarization magic‐angle spinning NMR, FT‐IR, Raman, and diffuse reflectance UV–Vis spectroscopies. The host–guest structures can act as supramolecular precatalysts for olefin epoxidation. Based on the model reaction of cis‐cyclooctene with hydroperoxide oxidants (tert‐butylhydroperoxide or hydrogen peroxide), the structural features of 1@CBn as well as the operating conditions influence the catalytic process. The metal species in 1@CBn undergo oxidative decarbonylation in situ, giving oxidized metal species that are catalytically active for olefin epoxidation. The type of oxidant and solvent influences the catalytic activity and stability. 1@CB8 was more stable than 1@CB7 with regard to catalyst recycling and reuse. Based on the substrate scope investigation, for relatively large olefins, such as the fatty acid methyl ester methyl oleate, the size of the macrocyclic host may be a determining factor for catalytic activity.

Enhanced photocatalytic activity of FeSO4 in a ZnO photocatalyst with H2O2 for dye degradation

In this study, the photocatalytic degradation efficiency of ZnO synthesized by a hydrothermal method and iron-supported ZnO catalysts by an impregnation method, dried (D) and calcined (C), was evaluated, through the degradation of methylene blue (MB) and methyl orange (MO) molecules under UV irradiation. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption, and UVvisible diffuse reflectance spectroscopy (DRS). XRD showed that FeSO4 is supported on ZnO, and the XPS study revealed higher concentrations of hydroxyl groups and Fe3+ for the dried catalyst. The bandgap energies were 3.24, 3.23, and 3.19 eV for ZnO, Fe/ZnO D and Fe/ZnO C, respectively. The results revealed that Fe/ZnO D with H2O2 exhibited a higher photocatalytic degradation efficiency than ZnO, achieving 97% and 99% degradation for MB and MO at 10 min, which implies that the integrated iron in ZnO serves as an electron-hole separator. In addition, the catalyst has a larger BET specific area, the presence of hydroxyl groups and sulfate ions on the surface of the catalyst with holes forms hydroxyl radicals (•OH), and the presence of Fe3+ on the surface catalyst with H2O2 produces more •OH radicals. •OH radicals are the major oxidation species in this process, which promotes the degradation of dyes. The photocatalytic dye degradation efficiency was also evaluated for various catalyst doses, dye concentrations and solution pH values. Moreover, the stability of the catalyst over repeated cycles of dye treatment was demonstrated.

Reversibly Cross-Linked Isoporous Membranes Fabricated by the Recyclable Block Copolymer with Pendent Dithiolane Groups.

The reversible formation and cleavage of disulfide bonds under physical/chemical stimuli make it a valuable motif in constructing dynamically cross-linked materials. In the present work, the block copolymer bearing pendent dithiolanes was synthesized and fabricated into isoporous membranes by the combination of self-assembly and nonsolvent-induced phase separation strategy. The cross-linking within the membrane was realized by the thiol-initiated ring-opening cascades of cyclic disulfides. Successful formation of disulfide bond networks within the isoporous membranes was proved by the Raman spectra, UV-vis diffuse reflectance spectroscopy, differential scanning calorimetry, and rheological analysis. The cross-linking in membranes was further demonstrated by the notably improved toughness and obviously enhanced swelling resistance to acid/alkaline solution as well as organic solvents. Importantly, the cross-linked isoporous membranes were fully dissolvable in solution containing dithiothreitol, which enabled the complete cleavage of disulfide bonds and successful recovery of the block copolymer that was able to be repeatedly fabricated into isoporous membranes with pore sizes identical to membranes prepared from the freshly synthesized copolymer. Our results indicate that dynamically cross-linked isoporous membranes with improved durability and good recyclability can be custom-made by simply incorporating active dithiolane moieties into self-assembling block copolymers.

Synthesis of Au‐decorated WO3 nanoplates for simultaneous oxidation of RhB and reduction of Cr(VI) under visible light irradiation

AbstractTungsten oxide (WO3) nanoplates were synthesized by a simple chemical precipitation technique. These nanoplates were decorated by Au nanoparticles via photoreduction route. The obtained samples were characterized by field emission scanning electron microscopy, X‐ray diffractometry and UV–vis diffuse reflectance spectroscopy to investigate their morphological, structural and optical properties. The SEM images show the plate morphology with the size in the range of 50–150 nm, their thickness ≈10 nm; spherical‐like Au nanoparticles ≈20 nm were attached to the surface of the WO3 plates. These materials were applied for the simultaneous photocatalytic degradation of Rhodamine B (RhB) and Cr(VI) under visible light. Due to the efficient separation of photoinduced charge carriers and the enhanced visible light absorption ability, the photocatalytic performance of Au‐decorated WO3 nanoplates was higher. The main active species responsible for the photodegradation reactions were identified by different scavengers and a photocatalytic mechanism was proposed. This work represents that WO3 nanoplates are a promising candidate for the degradation of organic and inorganic pollutants from the industrial wastewater under sun light exposure.

Facile one step green synthesis of CdO-CdS hybrid nanocomposite: Its electrochemical and photoluminescence applications

This study reports the fabrication of a CdO-CdS hybrid nanocomposite (CDCS NC) and its application towards electrochemical sensing of dopamine (DA). The synthesis was conducted at various temperatures using Butea monosperma leaf powder as a green fuel and it was noticed in the XRD pattern that 400 °C was ideal for the formation of the CdO-CdS hybrid NC. Also, the samples were characterized by implementing Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDX), UV-Vis Diffused Reflectance Spectroscopy (UV-DRS) and Photoluminescence (PL) techniques. The electrochemical activity was investigated using Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV) techniques. A working electrode was fabricated by modifying a Glassy Carbon Electrode (GCE) using the CdO-CdS NC and it showed remarkable electrochemical activity towards dopamine (DA). Further, the electrochemical properties were investigated by varying the scan rate, pH and concentration. The fabricated electrode shows a low limit of detection of 23 µM. Hence by its unique composition and inherent properties, the NC stands as a potent tool for advancing the boundaries of electrochemical sensing, heralding a new era of innovation in sensor development.

Green-synthesized flattened rice-shaped CuO and metal doped CuO nanoparticles using Bauhinia racemosa Lam. leaves extract and their photocatalytic and biological applications

In the present investigation, a sustainable approach to the biogenic fabrication of CuO nanoparticles (NPs) and transition metals (Co, Mn, and Zn) doped CuO NPs (TMDC NPs) was proposed by employing the Bauhinia racemosa (BR) Lam. leaves extract as a stabilizing and capping agent. The fabrication of CuONPs was immediately verified by a change in the color of the Cu solution from blue to dark grey. Characterizations of the bare CuO and TMDC NPs were done to attribute the physical and chemical characteristics of the NPs employing Fourier Transform Infrared (FT-IR), X-ray Diffraction (XRD), UV–Vis Diffuse Reflectance Spectroscopy (UV–Vis DRS), Photoluminescence (PL), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDX), Transmission Electron Microscopy (TEM), and Brunauer − Emmet − Teller (BET) studies. The acquired Co-CuO NPs demonstrated a substantial crystallinity, smaller crystallite size of ∼10.87 nm, lower bandgap, and reduced recombination rate and were implemented as an effective photocatalyst for the degradation of the amoxicillin (AMX) and tetracycline (TC) antibiotics, as examined by UV − vis spectrophotometric study and confirmed by a hypochromic shift. Based on UV − vis analysis, Co-CuO NPs demonstrated a potent and rapid photocatalytic degradation performance of ∼99 and ∼93 % for the AMX and TC antibiotics within 150 and 210 min respectively. Co-CuO NPs also demonstrated strong antimicrobial performance against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Aspergillusflavus, Aspergillusniger, and Bacillus subtilis. Further investigation of in-vitro cytotoxic potential against the A549 cell line, utilizing MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay and the free radical scavenging performance of the Co-CuO NPs was estimated by DPPH (2,2-diphenyl-1-picrylhydrazyl) assay utilizing L-ascorbic acid as reference were also performed.

Facile one-step preparation of Co2CrO4 spinel from heterometallic compounds – Structural, magnetic, electrical and photocatalytic studies

Two isostructural heterometallic complex salts with mononuclear units, [NH(CH3)2(C2H5)][Cr(terpy)2][CoCl4]2 (1) and [NH(CH3)(C2H5)2][Cr(terpy)2][CoCl4]2 (2), were synthesized using a building block approach and characterized by single-crystal and powder X-ray diffraction (XRD), impedance spectroscopy and magnetization measurements. They exhibit particular humidity-sensing properties and very high proton conductivity at room temperature. The magnetization of complexes shows the high spin state of 3/2 for tetrahedrally coordinated CoII ions, which on cooling remain in the paramagnetic state within the CrIII network, which is antiferromagnetically correlated. The prepared compounds were thoroughly explored as single-source precursors for the formation of the spinel oxide Co2CrO4 by their thermal decomposition. By optimizing the annealing temperature, heating/cooling rates and holding times, the phase composition of thermal processing of 1 or 2 was evaluated: phase pure spinel Co2CrO4 was obtained by thermal treatment already at 450 °C. The structure, morphology, and optical properties of spinel oxides prepared at different temperatures were characterized using powder XRD, field emission scanning electron microscopy (SEM) and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), while electrical and magnetic by impedance spectroscopy and magnetization measurements. The determined band gap energy and nanosized crystallites prompted us to investigate the photocatalytic activity of spinel oxide produced at 450 °C in the degradation of dyes Rhodamine B (RhB) and Methylene blue (MB) under Vis irradiation without and with assistance of hydrogen peroxide (H2O2). The results show that the Co2CrO4/H2O2 system exhibits a significantly higher photoactivity response; the degradation efficiency of MB and RhB was found to be 86.1% and 80.3%, respectively. The electrical conductivity spectra and the activation energy for the DC conductivity demonstrate the electronically semiconducting behaviour of the Co2CrO4 oxide. The Co2CrO4 spinel has a ferrimagnetic ground state, with mixed CoII and CoIII ions on the tetrahedral and octahedral sites: CoII having a high spin state on both sites and CoIII having a high spin state on the tetrahedral site and a low spin state on the octahedral site. Different thermal treatments affect the magnetization according to the different sizes of the obtained crystallites.

Pb3[O10Pb20](SiO4)4X10 (X = Cl, Br): The First Pb-Containing Halogen Silicates with Mirror-Symmetric Pseudo-Aurivillius Bilayers.

Two new congruently melting Pb-containing halogen silicates, Pb3[O10Pb20](SiO4)4X10 (X = Cl, Br), have been synthesized using a high-temperature solution method. Their crystal structures were determined by single-crystal X-ray diffraction, and both compounds crystallize in the orthorhombic space group Cmca. In both structures, the mirror-symmetric bilayer composed of Pb-O polyhedra is observed for the first time in Pb-containing silicates and belongs to α-PbO derivatives and is related to the Aurivillius phase. Thermal behavior analysis, UV-vis diffuse-reflectance spectroscopy, and IR spectroscopy were also performed. The Pb3[O10Pb20](SiO4)4Cl10 matrix was doped with Eu3+ ions as a dopant, and its potential application in fluorescence was confirmed from the resulting orange-red emission.

The conductivity of Nb2O5 enhanced by the triple effect of fluorine doping, oxygen vacancy, and carbon modification for improving the lithium storage performance.

In view of the inherent pseudocapacitance, rich redox pairs (Nb5+/Nb4+ and Nb4+/Nb3+), and high lithiation potential (1.0-3.0V vs Li/Li+), Nb2O5 is considered a promising anode material. However, the inherent low electronic conductivity of Nb2O5 limits its lithium storage performance, and the rate performance after carbon modification is still unsatisfactory because the intrinsic conductivity of Nb2O5 has not been substantially improved. In this experiment, taking the improvement of the intrinsic electrical conductivity of Nb2O5 as the guiding ideology, we prepared F-doped Nb2O5@fluorocarbon composites (F-Nb2O5@FC) with a large number of oxygen vacancies by one-step annealing. As the anode electrode of lithium-ion batteries, the reversible specific capacity of F-Nb2O5@FC reaches 150 mA g-1 at 5Ag-1 after 1100 cycles, and the rate performance is particularly outstanding, with a capacity up to 130 mA g-1 at 16Ag-1, which is far superior to other Nb2O5@carbon-based anode electrodes. Compared with other single conductivity sources of Nb2O5@carbon-based composites, the electrical conductivity of F-Nb2O5@FC composites is greatly improved in many aspects, including the introduction of free electrons by F- doping, the generation of oxygen vacancies, and the provision of a three-dimensional conductive network by FC. Through analytical chemistry (work function, UV-Vis diffuse reflectance spectroscopy, and EIS) and theoretical calculations, it is proved that F-Nb2O5@FC has high electrical conductivity and realizes rapid electron transfer.

Preparation, characterization and photocatalysis performances of superparamagnetic MgFe2O4@CeO2 nanocomposites: Synthesized via an easy and green sol–gel method

The characterization of MgFe2O4@CeO2 superparamagnetic nanocomposites was thoroughly investigated using powder X-ray diffraction (XRD), a vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), dispersive X-ray analysis (EDX), elemental mapping (MAP), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) and UV–Vis diffuse reflectance spectroscopy (DRS) analyses. The photocatalytic activity of the synthesized samples was evaluated as a novel magnetic nanocatalyst for degrading Congo red (CR) dye in an aqueous solution under visible light at room conditions. The results demonstrate that the efficiency of photocatalytic degradation is higher than that of absorbance and photolysis. The degradation efficiency of photodegradation is 93% within 49% of total organic carbon removal performance. The prepared MgFe2O4@CeO2 magnetic nanocomposites (MNCs) can be easily recovered and recycled for five repeated cycles, demonstrating potential extensive efficiency in magnetic nanocomposites in wastewater and water treatment. The nanoscale morphology of MgFe2O4@CeO2 MNCs was characterized as spherical, with a size range of 35–40 nm, utilizing SEM and TEM techniques. The saturation magnetization (Ms) of the resulting nanocomposites was analyzed by VSM, revealing a value of 3.58 emu/g. Furthermore, the surface area was determined to be 27.194 m2/g using BET analysis, and the band gap was identified as 2.85 eV through DRS analysis.