Ultraviolet Diffuse Reflectance Spectra Research Articles

Development of Fe/HNT and Fe/HNT-Al2O3 composite catalysts and application in successive treatment processes for pharmaceutical industry wastewater

The pharmaceutical industry wastewater (PIW) was treated by successive use of electro Fenton (EF) and photocatalytic oxidation (PcO) processes. Nano-particular powdered Fe/HNT (Iron/Halloysite nanotube) heterogeneous semiconductor catalyst was initially produced with Fe(OH)3 sludge modification precipitated after EF process. Thus, photocatalyst material was produced from the waste sludge and used in the PcO process. Photocatalyst Fe/HNT powder was immobilized on a three-dimensional (3D) reticulated Al2O3 ceramic support to enable rapid recovery of the catalyst from the PcO reactor system. Particle morphology and chemical configuration of the heterogeneous catalysts were analyzed with SEM (Scanning Electron Microscopy)-EDS (Energy-Dispersive X-ray spectrometry), UV-DRS (Ultraviolet Diffuse Reflectance Spectra) and XRD (X-ray diffraction). The Fe/HNT layer was calcined at three different temperatures (350, 450 and 600 °C). The optimum temperature was determined as 350 °C for better photocatalytic performance and practical reasons such as energy consumption. The successive use of EF + PcO processes for degradation of three different PIW samples was investigated by using two catalyst forms (nanoparticle and reticulated) and light sources (visible and sun light). The max TOC removal efficiency by EF + sun light-PcO (with Fe/HNT) successive treatment process was obtained as 78.4 %. Besides, the energy consumption value was calculated for optimum process state and calculated as 48.8 kWh/kg TOC at the EF + sun light-PcO (with Fe/HNT) successive treatment process.

Surface and quantum chemical parameters of nickel oxide nanostructures suited for ultraviolet-assisted cationic dye degradation

Nickel oxide (NiO) nanostructures were synthesized through chemical precipitation and subsequently analyzed using a scanning electron microscopy (SEM) and X-ray diffraction (XRD). Rietveld refinement of XRD data revealed a cubic structure with lattice parameters of a = b = c = 4.173 Å. Fourier transform infrared spectroscopy and energy dispersive X-ray were employed to analyze the functional group and elemental composition of NiO NPs. The ultraviolet diffuse reflectance spectra indicated an optical band gap of 3.08 eV for synthesized NiO nanoparticles. Surface characteristics were evaluated using the Gwyddion open-source application, and parameters including Ra (mean roughness), Rq (mean square roughness), Rsk (surface skewness), and Rku (kurtosis coefficient) were calculated. The chemical properties of NiO were investigated through density functional theory calculations, and the results aligned well with experimental data. Furthermore, a comparative analysis of the photodegradation of methylene blue (MB) and rhodamine B (RhB) in the presence of UV light was examined, and it followed pseudo-first-order rate kinetics with degradation efficiencies of 82.62% (MB) and 71.31% (RhB), respectively. The electric energy per order for the photodegradation process was calculated to be 9.4 × 102 kWh/m3/order (MB) and 11.7 × 102 kWh/m3/order (RhB). Notably, the low electric energy consumption per order indicated a cost advantage for the reactor setup.

SYNTHESIS, STRUCTURE AND ELECTROCHEMICAL PROPERTIES OF COPPER(II) COMPLEX WITH 3-PHENYLPROPYLMALONIC ACID

A 0D Cu-based complex {[(Complex 1, Complex 1 = Cu(L)2(EDA)2]n, L = 3-phenylpropylmalonic acid, EDA = ethylenediamine) was synthesized by solvent-thermal synthesis using 3-phenylpropylmalonic acid as the ligands. It is characterized and analyzed by PXRD, infrared spectrum, ultraviolet diffuse reflection spectrum and other means. Complex 1 is crystallized in triclinic crystal system with space group P-1, and each Cu2+ was coordinated with two ligands and a water molecule, respectively. Cyclic voltammogram curve of Complex 1 modified electrode (1+CPE) was tested in the PBS buffer solution (pH = 6.5), which found a pair of belong to Cu(Ⅱ)/Cu(Ⅰ) reversible redox peaks, proved that the Complex 1 can be used in the electrochemical applications.

Electrical conductivity and electrochemical studies of Cr-doped MoO3 nanoflakes for energy storage applications.

The growing demand for electricity has increased the interest of the researchers towards exploration of energy storing devices (ESDs). With the motif for developing electrochemical energy storage devices, this research work is focussed on the study of MoO3 nanoparticles and its doping with chromium as an efficient electrode material for energy storage applications. The nanoparticles were synthesized by hydrothermal method and were examined by powder X-ray diffraction, which determined the thermodynamically stable orthorhombic phase of MoO3, and their morphologies were examined using scanning electron microscopy displaying flake-like structures. The typical vibrational bands of Mo-O were identified from Infra-red and Raman spectral analysis. The ultra violet diffuse reflectance spectra revealed the decrease in optical band gap after doping with chromium. The temperature dependent AC and DC conductivities were enhanced on doping. Electrochemical behaviour of the nanoparticles was probed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) measurements and galvanostatic charge-discharge (GCD) analysis for which specific capacitance (C sp) value of 334 Fg-1 was achieved for Cr-doped MoO3 nanoparticles. The electrochemical performance of the sample was found to be increased after doping with Cr.

Use chloride to assist in constructing of penta- and nano-nucleus mixed-valent Cu(I/II) clusters and their photo-thermal properties

To prepare new series of mixed-valence polynuclear Cu(I/II) clusters, chloride ions are introduced to construct two mixed-valence polynuclear Cu(I/II) clusters for evaluating their photothermal conversion performance. X-ray single-crystal structural analysis reveals their molecular formula are {CuII[CuI(Cy3P)]4(BTA)4Cl2}·5DMF (I·5DMF, Cy3P = triscyclohexylphosphine, BTA = benzotriazole, DMF = N,N-Dimethylformamide) and {(CuII)3[CuI(PPh2Py)]6(BTA)8Cl4}·6DMF (II·6DMF, Ph2PyP = diphenyl-2-pyridylphosphine), respectively. X-ray Photoelectron Spectroscopy (XPS) and Electrospray Ionization Mass Spectrometry (ESI-MS) confirm their chemical composition and charge state. The reported two mixed-valence CuI/CuII clusters have different nucleus (penta-nucleus for I and nano-nucleus for II) and different proportion of valence state (1/4 for I vs 1/2 for II). The thermogravimetric analysis (TGA) reveals the thermal stability of both clusters is less than our previously reported penta-nucleus mixed-valence CuI/CuII clusters. Contrastively studies of their optical absorption properties by the solid-state ultraviolet diffuse reflection spectra indicate high-nucleus mixed-valence CuI/CuII cluster with higher proportion of CuII is superior to those penta-nucleus mixed-valent Cu(I/II) clusters. With the introduction of chloride ions to the structures of mixed-valence CuI/CuII clusters have not remarkably changed their photothermal conversion performance. This study provides a practicable way to construct new mixed-valence CuI/CuII clusters with different photothermal conversion performance.

Effect of Ni2+ substitution on magnetic, optical and electrical properties of SrFe2O4

Citrate gel combustion method is used for the synthesis of Ni2+ substituted strontium ferrite Sr1-xNixFe2O4 (x = 0.0, 0.2, 0.4, 0.6, 0.8). The characterization of synthesized material is done by different techniques. Fourier transform Infra-red (FT-IR) spectra revealed the inverse spinel structure and showed slight shift in spectrum. X-ray diffraction (XRD) patterns demonstrated the orthorhombic phase of spinel formation with trace of secondary phase impurity of SrCO3. Scanning electron microscopy (SEM) images showed agglomeration of particles. The effect of Ni2+ substitution in SrFe2O4 on structural, magnetic, optical and direct current (DC) electrical resistivity properties are investigated. Room temperature vibrating sample magnetometer (VSM) studies indicated increase in trend of saturation magnetization (Ms) and remanence magnetization (Mr) with increase in content of Ni2+ ion. The squareness ratio (SQR) Mr/Ms for SrFe2O4 is found to be 0.5752, while for remaining samples it is found to be less than 0.5 which demonstrated multi domain to single domain transition. Variation of band gap energy with Ni2+ substitution is reported with the help of ultra-violet diffuse reflectance spectra (UV-DRS). Temperature dependent DC electrical resistivity by two probe method measurement obeyed Arrhenius equation and revealed the typical semiconducting behavior of the samples. The change in slope of line observed in resistivity due to ferrimagnetic to paramagnetic transition in all samples attributed strong exchange interaction between the outer and inner electrons. Activation energy (Ea) for ferri and paramagnetic region is calculated. For ferrimagnetic region the Ea is found to increase with increasing Ni2+ content while, in paramagnetic region for Ni2+ substituted samples the Ea is found to be greater than 0.2 eV which inferred the hopping motion of small polarons are responsible for conductivity. The complex impedance spectra revealed the information about conduction mechanism.

Visible light-enable oxidation and antibacterial of zinc oxide hybrid chitosan photocatalyst towards aromatic compounds treatment

A solar-driven, ZnO-supported chitosan (ZnO/CS) photocatalyst has been formulated, with the aim of enhanced photocatalytic activities with a simple acidic mixing process and the gel solidification method. ZnO/CS, with a narrow band gap (2.89 eV) and macro-porous structure was confirmed under Ultra Violet Diffuse Reflection Spectra (UV DRS) and Transmission Electron Microscopy (TEM), respectively. The Field Emission Scanning Electron Microscopy (FESEM) revealed that average bead size of 100–250 µm of the photocatalyst with ZnO stayed in the hexagonal phase, dispersed, and embedded into CS. The adsorption and photocatalyst activity of the hybrid catalyst was investigated regarding the composition of the catalyst, catalyst dosage, pH of the solution, and concentration of the solution. The catalyst with a composition of 2:1 (ZnO/CS) demonstrates the optimum decolarization properties. Catalytic performances were recorded at up to 89% photodecolarization at pH 12 with 10 ppm of methylene blue under visible irradiation. This has brought a new approach for a highly efficient, stable, sustainable, and low-cost dye water treatment technology.

Influence of Wallach’s Rule on Chiral AIE Systems and Its Application in Cryptographic Information Storage

Influence of Wallach’s Rule on Chiral AIE Systems and Its Application in Cryptographic Information Storage

Photocatalytic Properties of Zinc Selenide and Cobalt Selenide Nanocomposite

In recent years, the environmental pollution caused by organic dyes has become more and more serious, so the removal of organic dyes has been paid more and more attention. In this work, ZnSe/CoSe was synthesized by hydrothermal method, and the activity of the composite photocatalytic materials was detected by visible light catalytic degradation of methylene blue. The nanocomposites were characterized by Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Energy Dispersive Spectrometer (EDS), X-ray Powder Diffraction (XRD), Ultraviolet Diffuse Reflection Spectrum (UV-Vis), Brunner−Emmet−Teller Measurements (BET), and X-ray Photoelectron Spectroscopy (XPS). The catalytic effect was the most obvious when the composite ratio was 1:7.5, with the removal rate reaching to 99.4 % of 20 mg/L MB within 120 min of visible light irradiation. Therefore, ZnSe/CoSe has a broader application prospect due to its high efficiency and low price.

Construction of Bi2O3/Bi28O32(SO4)10 three-dimensional microsphere heterojunction and the photoelectrocatalysis performance

Through electrodeposition and annealing, a Bi2O3/Bi28O32(SO4)10/FTO photoelectrode with three-dimensional spherical morphology was prepared. X-ray diffraction characterization (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Transmission electron microscope (TEM), ultraviolet diffuse reflection spectrum (DRS), electrochemicalimpedance (EIS), photoluminescence (PL), transient state photocurrent, Mott-Schottky and other methods were carried out to characterize the elemental composition, crystal morphology and optical properties, as well as the photocatalytic performance, respectively. The results showed that the film contains Bi, O and S elements. Bi2O3/Bi28O32(SO4)10/FTO electrode was 10.5 times the photocurrent density of the Bi28O32(SO4)10/FTO electrode and 2.15 times the photocatalytic degradation efficiency. Capture experiments showed that hydroxyl radicals (OH) and holes (h+) are the main reactants in the degradation process. The Bi2O3/Bi28O32(SO4)10/FTO composite electrode has good stability. After four degradation cycles, the removal rate of methylene blue was basically unchanged. The increase in photocatalytic activity is attributed to the increase in the visible light absorption range and the formation of heterojunction structures. Finally, the charge transfer mechanism of Bi2O3/Bi28O32(SO4)10/FTO was proposed.

Rapid synthesis and characterization of advanced ceramic-polymeric nanocomposites for efficient photocatalytic decontamination of hazardous organic pollutant under visible light and inhibition of microbial biofilm

Ceramic-polymeric 3C–silicon carbide-graphitic carbon nitride (3C–SiC@g-C3N4) nanocomposites were synthesized by decorating cubic phased, ceramic 3C-Silicon carbide (3C–SiC) on the framework of the nanosheets of metal free polymeric graphitic carbon nitride (g-C3N4) by single step pulsed laser ablation in liquid (PLAL) method. Morphological, structural, elemental and optical characterizations of the synthesized 3C–SiC@g-C3N4 nanocomposites were carried out. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM) studies confirm the perfect anchoring of 3C–SiC on g-C3N4 nanosheets in 3C–SiC@g-C3N4 nanocomposites synthesized by PLAL method. Ultra-violet diffuse reflectance spectra (UV-DRS) of 3C–SiC@g-C3N4 indicated the enhancement of visible light absorption and also the narrowing down of band gap energy in 3C–SiC@g-C3N4 nanocomposites, as a result of the anchoring of 3C–SiC on g-C3N4. Also we noticed the decrease of photoluminescence (PL) emission intensities in the PL spectra of 3C–SiC@g-C3N4 with respect to pure g-C3N4, which indicates the reduced photo-induced charge recombination by the presence of 3C–SiC content on g-C3N4 nanosheets. In the application side, PLAL synthesized 3C–SiC@g-C3N4 nanocomposites exhibited enhanced visible light driven photocatalytic degradation of methylene blue dye in water, improved antibacterial activity against Pseudomonas aeruginosa (gram-negative) and Staphylococcus aureus (gram-positive) bacteria, and also served as better inhibiting agent for biofilm formation, compared to pure g-C3N4 nanosheets. It is quite obvious from our studies that this ceramic-polymeric nanocomposite, 3C–SiC@g-C3N4 has the potential application for antibacterial and anti-biofilm activities in addition to its remarkable photocatalytic performance.

Synthesis of cadmium sulfide-tungsten trioxide nanocomposites for photo-catalytic degradation of organic pollutants and growth retardation of waterborne bacteria and biofilms

Nanocomposites of cadmium sulfide-tungsten trioxide (CdS@WO3), with different CdS content (2.5 %, 5 % and 10 %) in WO3 were synthesized by laser defect engineering in liquid (LDL). In the characterization studies, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscope (TEM) and high-resolution transmission electron microscope (HR-TEM) studies showed the perfect anchoring of CdS nanoparticles on the surface of bigger WO3 nanoparticles in CdS@WO3 nanocomposites. In the optical characterization, ultra-violet diffuse reflectance spectra (UV-DRS) indicated the narrowing down of band gap energy in CdS@WO3, and consequent enhancement of visible light absorption compared to pure WO3. Also photoluminescence (PL) implied the reduced charge recombination in CdS@WO3, compared to that of pure WO3, which can be attributed to the typical Z-scheme charge transfer between the composite partners. The LDL synthesized CdS@WO3 nanocomposites were used as (i) a photocatalyst for the degradation of Rhodamine B dye in water, (ii) anti-microbial agent against multi drug-resistant Pseudomonas aeruginosa (MDR-PA) and Methicillin-resistant Staphylococcus aureus (MRSA) bacteria, (iii) biofilm growth retardation agent against biofilm-producing strains of MRSA and MDR-PA. In all the three applications CdS@WO3 nanocomposite in general revealed a better performance than pure WO3, particularly 5 % CdS content in the composite (5 %-CdS@WO3), was the optimum for photocatalytic degradation and 10 % CdS content in CdS@WO3 showed the best performance in antibacterial and biofilm growth retardation applications for both bacterial strains.

Synthesis and characterization of cellulose/TiO2 nanocomposite: Evaluation of in vitro antibacterial and in silico molecular docking studies

Cellulose/TiO2 nanocomposite was synthesized using coagulation in sodium hydroxide-thiourea-urea aqueous solution medium by precipitation method. This method was accomplished green and cost-effective for the fabrication of composite nanomaterials. Structure, morphology and optical properties of the nanocomposite were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, and ultraviolet diffuse reflectance spectra respectively. XRD results showed the anatase structure of TiO2 while FESEM micrograph showed evidence of particle size ranging from 20 to 40 nm for cellulose/TiO2 nanocomposite. The Fourier transfer infrared spectroscopy investigation reveals that the TiO2 is bound to hydroxyl groups to the cellulose by hydrogen bonding. The optical energy bandgap is found to be 2.71 eV for nanocomposite from the UV-DRS. The mechanical strength of the composites gently escalated with the addition of TiO2 nanoparticles into cellulose polymer matrix. Cellulose/TiO2 nanocomposite was screened for their in vitro antibacterial activity against Staphylococcus aureus and Escherichia coli bacteria have been investigated. Additionally, the results obtained from in silico molecular docking studies confirm the interaction of nanocomposite with proteins, were in good agreement with the experimental data. This finding provides a novel and simple method for the synthesis of cellulose/TiO2 nanocomposite as functional biomaterials.

Neutral and alkaline chemical environment dependent synthesis of Mn3O4 for oxygen evolution reaction (OER)

Co-precipitation assisted hydrothermal synthesis was employed to prepare Mn3O4 electrocatalysts for efficient electrochemical water oxidation. Tetragonal structure of high crystalline and pure phase Mn3O4 nanostructures was confirmed by X-ray diffraction (XRD) spectra. Physical characteristics such as vibration, optical and morphology of the electro catalysts were examined and confirmed by Raman spectra, Fourier Transform Infrared Spectra (FTIR), photoluminescence spectra (PL) and ultra-violet diffuse reflection spectra (UV-DRS) respectively. Mn3O4 electro catalysts were deposited on GCE electrode for investigating the electrochemical behavior. The electrochemical water splitting application was demonstrated by the prepared Mn3O4 electro catalysts in conventional three electrode cell with Hg/HgO as a reference electrode and Pt mesh as a counter electrode. Higher current density of 1.31 mA/g with lowest Tafel slope value of 63 mV/dec was achieved for the prepared electro catalyst synthesized in base pH condition. Good stability of 55% over 12 h long time was achieved for the electro catalysts in alkaline medium under continuous electrochemical reaction with good retention in performance. Hence, the controlled alkaline environmentally synthesized Mn3O4 electro catalysts prepared in this work achieved the good standard of highly efficient electrode material for electrochemical water splitting applications.

Synthesis of high specific surface area titania monolith by addition of poly (ethylene oxide)

The macro-mesoporously bimodal titania monolith with high surface area was synthesised via a template-free sol–gel route using titanium isopropoxide as titania source and poly(ethylene oxide) as an improver of the pore structure and specific surface area. The effects of poly(ethylene oxide) on the shape and specific surface area of the titania monolith were determined. The titania monolith was characterised by scanning electron microscope, Brunauer–Emmett–Teller method and ultraviolet diffuse reflectance spectra measurements. The obtained titania monolith shows excellent surface properties with macropore of 2 µm, mean pore size of 15·2 nm, Brunauer–Emmett–Teller surface area of 110·3 m2 g−1, cumulative pore volume of 0·32 mL g−1 and a narrow pore size distribution after 350°C calcination.

Temperature-Programmed Reduction Studies of V-Ag Catalysts

In H2/N2atmosphere, the reduction behavior of V-Ag catalysts with V/Ag atomic ratios 1/0, 9/1, 3/1, 2.16/1, 1.5/1, 1/1, and 0/1 were studied by temperature-programmed reduction (TPR), X-ray diffraction (XRD), and ultraviolet diffuse reflectance spectra (UVDRS). The results showed that the reduction processes of Ag2V4O11, Ag2V4O10.84, and Ag1.2V3O8are all the same while the reduction temperature was raised; they were first reduced to Ag and V6O13, then to VO2, and thence to V2O3subsequently. To vanadium oxides in V-Ag catalysts, the reactions with hydrogen were accelerated and the peak temperatures (TM) of TPR were decreased explicitly due to the addition of silver element.

Ultra-violet diffuse reflectance spectra of the hydrated oxides of protactinium(V) and of niobium(V) and some related compounds

Protactinium(V) and niobium(V) hydrated oxides present single absorption bands at 260 and 268 nm, respectively. The anhydrous oxides show additional lower energy bands whose relative intensities depend on their crystalline structures. The 260 and 268 nm bands are attributed to the MOM bonds in a disordered environment. Protactinium peroxide and protactinium oxalate, hydrolytic compounds where the “hydrated oxide structure” is likely to be preserved, have spectra resembling that of the hydrated oxide. On the contrary, the true complex potassium oxotrioxalatoniobate(V) has an absorption spectrum bearing little resemblance to that of the hydrated niobium oxide. The assignment of the 260 nm band to the PaOPa bonds may thus account for the absorption in the 240–300 nm region which is generally associated with the hydrolysis of Pa(V) in several aqueous media.