Ultraviolet-visible Diffuse Reflectance Spectroscopy Research Articles

Catharanthus roseus-mediated CuAl2O4 nanocomposites for evaluation of killing kinetics

The present article portrayed on the killing kinetic of human pathogenic bacteria using bioinspired mesoporous CuAl2O4 nanocomposites (NCs). The NCs was fabricated using leaf extract of medicinal plant Catharanthus roseus (CR) as a green reducer and stabilizer. As bio-fabricated material was calcined at 800 °C and characterized by several analytical techniques like X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV-DRS), Energy Dispersive X-Ray Spectroscopy (EDS), X-Ray Photoelectron Spectroscopy (XPS), Raman, Brunauer-Emmett-Teller (BET), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM) to authenticate its structure, phase, chemical bonding, chemical state, size and morphology behaviors. XRD and TEM revealed a reduced crystallite and nanoscale sizes of biosynthesized NCs. Moreover, XRD study exposed a cubic-structure of material, while transmission electron microscopy rendered an average particles size in range 10–15 nm. However, BET profile advocates a mesoporous nature of the particles. An effective biological molecular docking modulation assessed by substituting natural inhibitor by bioinspired NCs, while the protein PDB ID 4Z8D FabH as a receptor site for the present investigation. After assessment of molecular docking examination, the antibacterial activity of bioinspired NCs were performed against Staphylococcus aureus, Bacillus subtillis, Klebsiella pneumoniae and Escherichia coli using agar-well method. The broth culture method was employed on different pathogenic strains by kinetic growth assays and colony forming unit.

Antibacterial and antiviral PA6-AgNPs microfibers for application as a filter element in facial respirators

Polymeric microfibers are very interesting materials that can be associated with other nanomaterials aiming to obtain specific properties and be used in a wide range of applications. In this study, we prepared different formulations of polyamide 6 (PA6) containing silver nanoparticles (AgNPs) and produced microfibers by solution blow spinning technique for its use as a filter element in a face respirator. The obtained samples were then characterized by field emission gun-scanning electron microscopy (FEG-SEM), energy dispersion spectroscopy (EDS), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), water contact angle (WCA), thermogravimetric analysis (TGA), and respirability and antibacterial, antiviral and cytotoxicity assays. In general, the microfibers were well dispersed and the AgNPs were evenly distributed throughout the samples, reflecting a hydrophilic character and good thermal stability, with a maximum weight loss of 2.9 % attributed to the evaporation of water molecules. The sample produced with a concentration of 10 mmol/L of silver nitrate presented acceptable levels of resistance to respiration. Concerning the microbiological analyses, the results showed that samples evidenced antibacterial effect against Escherichia coli and Staphylococcus aureus, forming inhibition halos of up to 4 mm in disk diffusion assays and inhibiting bacterial growth in liquid medium assays, as well as antiviral effect against betacoronavirus MHV-3, promoting a reduction of up to 99.9 % of viral particles. Moreover, the samples presented cytotoxicity on the first and second days, whereas on the seventh day some of the extracts did not show cytotoxic activity, indicating that the cells adapted to the culture medium. Considering the data set and the simple process of obtaining the microfibers, it was possible to conclude that this material can be applied as a filter element in a face respirator as well as in a variety of products with antibacterial and antiviral purposes.

Exploring the gas sensing potential of BiOBr0.9I0.1: A highly responsive sensor for ammonia detection at room temperature

Bismuth halide oxides (BiOX, where X = Cl, Br, I) are renowned in photocatalysis for their distinct layered structure, modifiable band gap, and affordability. However, their application in gas sensing has garnered comparatively less research attention. Notably, solid solutions of BiOX demonstrate superior attributes over pure BiOX compounds. BiOBrxI1-x solid solution was successfully synthesized using in situ precipitation method and used as a gas-sensitive material for ammonia (NH3) gas sensor. The structural and compositional integrity of the synthesized samples was meticulously confirmed by X-ray diffraction (XRD), which revealed the coexistence of different BiOBr and BiOI phases. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) provided insights into the morphology, revealing a flower-like nanostructure, which favors the surface reaction rate. The electronic and optical properties of the material were further elucidated by photoluminescence (PL) spectroscopy and ultraviolet–visible diffuse reflectance spectroscopy (UV-DRS), which revealed that the band gap is tailored to facilitate the sensitivity and selectivity of ammonia detection. Key properties including surface area and porosity were quantitatively evaluated by Bruner-Emmett-Taylor (BET) analysis and found BiOBr0.9I0.1 sensor to have a specific surface area of 13.08 m2/g. Specifically, the BiOBr0.9I0.1 sensor's response ratio (Ra/Rg) to 100 ppm of ammonia reaches 8, approximately fourfold higher than that of the pure BiOBr sensor. The flower-like morphology of BiOBr0.9I0.1 enhances surface activity and charge transfer efficiency, thereby facilitating greater gas adsorption and elevating sensor performance. The rapid response and recovery times (12/24 s at 30 ppm), low detection threshold (LOD, 0.75 ppm), along with its selectivity and reproducibility at room temperature, position the BiOBr0.9I0.1 material as a promising candidate for ammonia gas detection.

Preparation, characterization and photocatalytic studies of defect pyrochlore, KMn0·33Te1·67O6 and its composite with g-C3N4

Skeletal materials belonging to the defect pyrochlore family have been the subject of considerable interest due to their remarkable properties. In this work, a highly efficient, stable and visible light active composite photocatalytic system consisting of defect pyrochlore of composition KMn0·33Te1·67O6 (KMnTeO) and g-C3N4 (g-CN) has been successfully prepared by simple physical mixing of pre-prepared KMnTeO and g-CN components synthesized in solid state and thermal treatment of low-cost melamine, respectively. Structural, morphological and optical properties of as-prepared catalysts were deduced from powder X-ray Diffraction (XRD), Fourier Transform Infrared (FT-IR), Raman, Field Emission Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (FESEM-EDX), Transmission Electron Microscopy-High Resolution Transmission Electron Microscopy (TEM-HRTEM), Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV–Vis DRS), X-ray Photoelectron Spectroscopy (XPS) and Photoluminescence (PL) measurements. The lattice parameter “a” of parent KMnTeO was obtained from Rietveld refinement of its powder XRD pattern. The FT-IR and Raman spectra of KMnTeO gave characteristic bands belonging to the defect pyrochlore structure. The photocatalytic activities of KMnTeO and composite KMnTeO-g-CN were evaluated by the degradation of methylene blue (MB). Scavenger experiments were carried out to identify the reactive species responsible for the degradation of MB. Furthermore, the reusability and stability of the photocatalysts were explored. The probable photocatalytic mechanism for MB degradation over the composite KMnTeO-g-CN was surmised according to the scavenger experiments. The work provides a new approach for the development of novel defect pyrochlore based composite photocatalysts to treat industrial wastewater containing organic pollutants.

Visible-light-driven photocatalytic degradation of doxycycline using TiO2/g-C3N4/BIOCHAR catalyst

Abstract TiO2/g-C3N4/biochar (TCNBC) catalysts were prepared by the hydrolysis method for the photocatalytic degradation of doxycycline antibiotic (DC), with biochar obtained from the pyrolysis of Phragmites australis. The catalysts were examined using scanning electron microscope (SEM), transmission microscopy (TEM), energy dispersive X-ray spectrometer (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), photoluminescence spectroscopy (PL), and ultraviolet-visible diffuse reflectance spectroscopy (UV–Vis DRS) and nitrogen adsorption/desorption. The photocatalytic activity results showed that the TCNBC catalyst exhibited higher catalytic activity than pure TiO2 or g-C3N4. Its peak catalytic activity, achieving a decomposition efficiency of 91.93% and a mineralization efficiency of 81.50%, can be attributed to the synergistic effect of biochar, TiO2, and g-C3N4. Even after four cycles of use, the catalyst still maintained relatively high activity for the degradation of DC. The photocatalytic degradation efficiency of TCNBC decreased from 91.93% to 86.30% after four recycling events.

Facile fabrication of bifunctional ternary nanocomposite (FCPTNC) as an efficient catalyst for 4-nitrophenol reduction and crystal violet photodegradation

The synthesis of a ternary nanocomposite Fe3O4/CuO-Ppy (FCPTNC) was effectively achieved via hydrothermal and in-situ chemical oxidative polymerisation techniques. FCPTNC was used as a catalyst for reducing the toxic compound 4-nitrophenol to the non-toxic compound 4-aminophenol. Additionally, it was utilised for the visible-light-induced degradation of the crystal violet (CV) dye. FCPTNC underwent characterisation using various techniques, namely X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), ultraviolet–visible diffuse reflectance spectroscopy (UV-DRS), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR). The successful preparation of the nanocomposite was validated through analysis of its structural properties. Moreover, examining its optical properties indicated that the nanocomposite can effectively operate through visible light irradiation. The catalyst demonstrated exceptional catalytic efficacy in eliminating the targeted organic pollutants, namely 4-nitrophenol (4-NP) and crystal violet (CV). The catalyst exhibited a degradation efficiency of 97 % for CV dye within60 min. It achievedthecomplete conversion of 4-nitrophenol into its corresponding amino derivative within15 min. The calculated first-order rate constants for the reduction of 4-NP and photodegradation of CV dye were found to be in the range of 0.53–11.6 × 10−2 min−1 and 3.2–5.6 × 10−2 min−1, respectively. The magnetic catalyst exhibited efficient separation from the reaction media and was successfully recycled for up to fiveconsecutive cycles with negligible loss of catalytic activity. The work demonstrates that the FCPTNC nanocomposite has favourable characteristics, such as facilesynthesis, efficient catalytic activity, and reusability. These findings suggest that the nanocomposite possesses desirable efficiency and durability, rendering it a promising catalyst for environmental applications.

Synergistic photocatalytic removal of moxifloxacin from aqueous solutions using ZnO-Fe3O4-chitosan composites

The escalating contamination of water bodies with antibiotic residues is an urgent environmental and public health issue. This study aimed to fabricate an innovative photocatalytic composite (CMZ) by combining chitosan, magnetic iron oxide (Fe3O4), and zinc oxide (ZnO) for efficiently removing antibiotic moxifloxacin (MFX) water. Comprehensive characterization of the fabricated CMZ was performed using various techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), photoluminescence spectroscopy (PL) and nitrogen adsorption/desorption isotherm analysis. The synergistic incorporation of ZnO, Fe3O4, and chitosan in the CMZ composite altered the structural properties of ZnO and chitosan The band gap energy of CMZ was 2.58 eV, significantly boosting its photocatalytic effectiveness under visible light exposure. The CMZ composites exhibited a high efficiency in catalyzing MFX degradation in aqueous environments. The optimal conditions for MFX degradation were established, including a neutral pH level of 7, a 90 min exposure to irradiation, and employing 0.1 g of the CMZ catalyst. The degradation process obeyed closely to the first-order kinetic model. The CMZ material showed consistently high performance in degrading MFX across four consecutive reuse cycles, emphasizing its practical applicability for mitigating antibiotic pollution.

Photocatalytic ozonation-based degradation of phenol by ZnO–TiO2 nanocomposites in spinning disk reactor

Spinning disk reactor (SDR) has emerged as a novel process intensification photocatalytic reactor, and it has higher mass transfer efficiency and photon utilization for the degradation of toxic organic pollutants by advanced oxidation processes (AOPs). In this study, ZnO–TiO2 nanocomposites were prepared by sol-gel method, and coated on the disk of SDR by impregnation-pull-drying-calcination method. The performance of catalyst was characterized by X-ray diffraction, scanning electron microscope, X-ray photoelectron spectroscopy, photoluminescence and ultraviolet–visible diffuse reflectance spectroscopy. Photocatalytic ozonation in SDR was used to remove phenol, and various factors on degradation effect were studied in detail. The results showed that the rate of degradation and mineralization reached 100% and 83.4% under UV light irradiation after 50 min, compared with photocatalysis and ozonation, the removal rate increased by 69.3% and 34.7%, and mineralization rate increased by 56.7% and 62.9%, which indicated that the coupling of photocatalysis and ozonation had a synergistic effect. The radical capture experiments demonstrated that the active species such as photogenerated holes (h+), hydroxyl radicals (·OH), superoxide radical (·O2−) were responsible for phenol degradation, and ·OH played a leading role in the degradation process, while h+ and ·O2− played a non-leading role.

Azo chromophore functionalized polyesters; Synthesis, characterizations and applications for efficient electrocatalyst for oxygen evolution reaction and heavy metal ion detection

The current study focuses on the synthesis, characterization and investigation of the potential applications of azo chromophore functionalized polyesters and their composites with graphene derivatives. Employing the two-step diazotization coupling reaction, diazo diol monomers are synthesized. Subsequently, the azo polyesters are prepared via low-temperature solution polycondensation of the diazo diols with diacid chloride followed by the incorporation of graphene derivatives to obtain composite materials. Characterization techniques including Fourier transform Infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Ultraviolet-Visible Diffuse reflectance spectroscopy (UV-Vis DRS) and Scanning electron microscopy (SEM) are employed to evaluate the chain structure, degree of crystallinity, optical properties and morphology. Further, their electrocatalytic activity towards the oxygen evolution reaction (OER) and detection ability toward heavy metal ion was evaluated. The results demonstrate enhanced catalytic and detection capabilities attributed to synergistic interactions between polymer and graphene components. This study provides significant insights into the development of efficient polymer-graphene hybrid materials, with potential applications in green chemistry and environmental monitoring.

Photocatalytic degradation of methylene blue under visible light by cobalt ferrite nanoparticles/graphene quantum dots.

A simple approach was developed to synthesize cobalt ferrite nanoparticles/graphene quantum dots (CF/GQDs). The material was prepared from a homogeneous mixture of iron nitrate, cobalt nitrate, and starch at 140, 180 and 200 °C in a 24 h thermal hydrolysis process. The obtained materials were characterised by using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy, Fourier-transform infrared spectroscopy, photoluminescence spectroscopy, vibrating-sample magnetometry, and nitrogen adsorption/desorption isotherms. Cobalt ferrite crystals of around 8-10 nm and graphene quantum dots formed directly at 200 °C. Stacking GQDs sheets onto the CF nanoparticles resulted in CF/GQDs nanoparticles. The nanocomposite exhibits satisfactory fluorescent and superparamagnetic properties, which are vital for catalytic applications. The CF/GQDs catalyse significantly the degradation of methylene blue (MB) under visible light. The catalyst can be recycled with an external magnetic field and displays suitable stability. Also, it was reused in three successive experiments with a loss of efficiency of about 5%. The CF/GQDs are considered as an efficient photocatalyst for MB degradation and other dyes.

Optical CuAl2O4 used as photocatalyst for IC dye degradation

ABSTRACT The nanocrystalline copper aluminate (CuAl2O4) has been successfully synthesized by a simple, economical, and environmentally friendly solid-state mechanochemical (MCH) method. The prepared sample was characterized by a variety of suitable methods employed, including scanning electron microscopy (SEM), ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS), Fourier transform infrared spectroscopy (FT-IR), and X-ray powder diffraction (XRD). The material's average particle size was 55 nm and stoichiometric. CuAl2O4 has been found to exhibit potent photocatalytic activity toward indigo carmine (IC) when subjected to UV light. Under UV radiation, 10 mg CuAl2O4 leads to 99 ± 1% degradation of an 8 ppm IC dye solution among 2 ppm, 4 ppm, 6 ppm, 8 ppm, and 10 ppm in 25 min. In addition, a prospective liquid chromatography-mass spectrometry (LC-MS) technique is identified in the current work, which provides potential routes for the photocatalytic breakdown of IC. Even after five consecutive cycles, the photocatalyst showed remarkable reusability and stability.

Spatial Distribution of Brønsted Acid Sites Determines the Mobility of Reactive Cu Ions in the Cu-SSZ-13 Catalyst during the Selective Catalytic Reduction of NOx with NH3.

The formation of dimer-Cu species, which serve as the active sites of the low-temperature selective catalytic reduction of NOx with NH3 (NH3-SCR), relies on the mobility of CuI species in the channels of the Cu-SSZ-13 catalysts. Herein, the key role of framework Brønsted acid sites in the mobility of reactive Cu ions was elucidated via a combination of density functional theory calculations, in situ impedance spectroscopy, and in situ diffuse reflectance ultraviolet-visible spectroscopy. When the number of framework Al sites decreases, the Brønsted acid sites decrease, leading to a systematic increase in the diffusion barrier for [Cu(NH3)2]+ and less formation of highly reactive dimer-Cu species, which inhibits the low-temperature NH3-SCR reactivity and vice versa. When the spatial distribution of Al sites is uneven, the [Cu(NH3)2]+ complexes tend to migrate from an Al-poor cage to an Al-rich cage (e.g., cage with paired Al sites), which effectively accelerates the formation of dimer-Cu species and hence promotes the SCR reaction. These findings unveil the mechanism by which framework Brønsted acid sites influence the intercage diffusion and reactivity of [Cu(NH3)2]+ complexes in Cu-SSZ-13 catalysts and provide new insights for the development of zeolite-based catalysts with excellent SCR activity by regulating the microscopic spatial distribution of framework Brønsted acid sites.

Optical and dielectric properties of divalent copper based double perovskite compound, Gd2CuTiO6

In this work, we have investigated high temperature dielectric properties and room temperature optical properties on rare earth ion based orthorhombic Gd2CuTiO6 (GCTO). Optical properties like reflectance and band gap were determined from ultra-violet visible (UV–Vis) diffuse reflectance spectroscopy technique and photoluminescence (PL) spectrum. The compound exhibited substantial optical absorption and emission in the visible region. Our findings reveal the presence of an intermediate band, as evidenced by the difference between the band gap values obtained from the Tauc plot using the diffuse reflectance spectrum (3.07 eV) and the PL spectrum (2.4 eV). Furthermore, thermogravimetric analysis demonstrated high thermal stability with <0.4% change in mass over a wide temperature range of 30 °C–1200 °C in air environment. Moreover, lead-halide free compound, GCTO is highly thermally stable oxide double perovskite with wide band gap and absorption in the UV–Vis range are highly suitable for optical applications In addition, dielectric properties of the compound have been examined using impedance spectroscopy as a function of frequency ranging from 500 Hz to 1 MHz and temperature between 300 K and 550 K. Compounds with relaxor behaviour at high temperatures and high thermal stability are desired for several applications. Because of the cation disorders present in this compound, GCTO displays dielectric relaxor behaviour indicative of a distribution of relaxation times. Furthermore, the frequency-dependent modulus illustrated a thermally activated conduction mechanism. Cole–Cole plots of electrical modulus suggest prominent grain contribution above 350 K.

Carbon-doped Bi2MoO6 nanosheet self-assembled microspheres for photocatalytic degradation of organic dyes

Abstract In this paper, carbon-doped Bi2MoO6 (C-Bi2MoO6) nanosheet self-assembled microspheres were prepared by using the solvothermal-calcination route to improve the photocatalytic activity of Bi2MoO6. The characterization results of x-ray diffractometry, Fourier transform infrared spectrometry, Raman scattering, scanning electron microscopy, transmission electron microscopy, BET specific surface area test, and x-ray photoelectron spectrometry indicated that C replaced the O2− anion in the Bi2MoO6 lattice, thinning the nanosheets, decreasing the size of the microspheres, and increasing the specific surface area of the Bi2MoO6. Ultraviolet–visible diffuse reflectance spectroscopy, photoluminescence, electrochemical impedance spectroscopy, transient photocurrent, and linear sweep voltammetry (LSV) spectroscopy demonstrated that the carbon doping reduced the band gap energy, raised the conduction band, and enhanced the photogenerated electron–hole pairs separation efficiency of Bi2MoO6. Benefiting from these favorable changes, the C-Bi2MoO6 microspheres prepared at a molar ratio of C to Bi of 4 (4C-Bi2MoO6) exhibited the highest photocatalytic activity, and the photocatalytic degradation rate constant of rhodamine B by 4C-Bi2MoO6 microspheres was almost 2.26 times that by pristine Bi2MoO6 under simulated solar light. 4C-Bi2MoO6 microspheres (0.2 g/L) presented excellent photocatalytic performance toward RhB (20 mg/L) at pH value 1 and could remove 98.31% of the RhB within 120 min. In addition, 4C-Bi2MoO6 microspheres also possessed a high photocatalytic activity toward methylene blue and tetracycline. 4C-Bi2MoO6 microspheres assembled from thin nanosheets can be used as effective photocatalysts to degrade toxic organic molecules from wastewater.

Nano-ZnO prepared by using chaya and mango leaves extract for photocatalyst of methylene blue

This research aimed to synthesize nano-ZnO from chaya (Cnidoscolus aconitifolius) and mango leaves extract (Mangifera indica) as environmentally friendly photocatalysts. Nano-ZnO was synthesized using green synthesis, with leaves extracts as reducing agents and nanoparticle size stabilizers. The samples were prepared using two methods, namely nano-ZnO-1 and nano-ZnO-2. The results of Fourier transform infrared spectroscopy (FTIR) analysis showed the contribution of metabolite compounds in nano-ZnO synthesis. X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed the crystal size in nano range, with spherical nanorod morphology observed. Ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS) determined the band gap energy of 2.97 eV and 3.17 eV. Furthermore, photocatalytic activity test showed that photocatalyst performance after 90 min was 68.86% (nano-ZnO-1) and 96.46% (nano-ZnO-2).

Photocatalytic Degradation of Tetracycline Hydrochloride Based on the Structure-Property Exploration of BiOCl.

The correlation between structure and properties in the photodegradation reaction of bismuth oxychloride (BiOCl) was explored in this work. Three BiOCl samples with different sizes, morphological structures, and defects were prepared through a hydrothermal method with experimental manipulation. Their structural properties were comprehensively characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, electron spin resonance, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, and photoluminescence. Taking the photodegradation of tetracycline hydrochloride (TC-HCl) as the probe reaction, we found that high activity could be achieved by decreasing their crystal size and thickness, introducing proper defects in the structure, and assembling the nanosheets to get microball structure. Combined with radical-scavenge experiments and electron spin resonance (ESR) spin-trap spectra, we conclude that ̇O2- was the dominant reactive oxygen species for the degradation reaction. The degradation detailed pathway of TC-HCl was further analyzed using liquid chromatography-mass spectrometry. This work explores the structure-property correlation of BiOCl and provides strategies for the rational design of active photocatalysts for water remediation.

Single-step propane transformation on vanadium-supported catalyst revealed by operando DRS UV–vis study

The present study investigated the influence of silica support texture on the catalytic performance of VOx/silica catalysts in the selective oxidation of propane. Two- and three-dimensional mesoporous materials, SBA-15 and MCF, were synthesized using hydrothermal methods to create different pore structures. Vanadium (approximately 5 wt%) was incorporated into the silica matrices (MCF, SBA-15) and SiO2 (used as a reference system) through impregnation. The surface composition, valence state, and reducibility of the VOx species accommodated in VOx/silica catalysts were characterized using X-ray diffraction (XRD), diffuse reflectance ultraviolet–visible spectroscopy (UV–vis DRS), temperature-programmed reduction with hydrogen (H2-TPR), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) techniques. The catalytic properties of the catalysts were evaluated in the propane selective oxidation conducted at 470 °C, utilizing a mixture of oxidants (N2O and O2). Propane oxidation resulted in propane conversion of 34 %, propene selectivity of 49 %, and propene oxide selectivity of 20 %, corresponding to space–time yield of propene reaching 37 gC3H6 kgcat−1·h−1and propene oxide equal to 20 gPO kgcat−1h−1. The textural properties of the support materials noticeably influenced the stability of the catalysts. The vanadium catalysts supported on three-dimensional mesocellular silica foams (MCF) demonstrated superior activity, achieving turnover frequency (TOF) values of 9.0 × 10−4 s−1 for propene and 6.67 × 10−4 s−1 for propene oxide (PO). The unique three-dimensional ultra-large pores of the MCF material facilitated the generation of significant amounts of propene oxide, along with propene, while minimizing the formation of CO, CO2, and other oxygen-bearing by-products. Operando UV–vis studies supported by two-dimensional correlation analysis (2D COS) were employed to explain the diversity in the catalytic performance of VOx/silica catalysts. It has been found that the oligomeric vanadium species are the active sites in propane oxidative dehydrogenation, whereas the monomeric forms participate in propene oxide formation. Moreover, the reduction of V5+ to V4+ and even V3+ was identified as a crucial step in the reaction.A reaction scheme has been proposed based on catalytic experiments and spectroscopic insights.

Photocatalytic degradation of xanthates under visible light using heterogeneous CuO/TiO2/montmorillonite composites

Due to the significant demand for xanthate treatment in mineral effluents, photocatalytic techniques have emerged as one of the most promising solutions. In this study, a high-performance TiO2/CuO/montmorillonite photocatalyst was prepared. In this configuration, TiO2 was the classic photocatalytic material and CuO and montmorillonite were utilized to broaden the adsorption range of solar light and acted as carriers to support the photocatalyst. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy were employed for the comprehensive characterization of the microstructure of the ternary photocatalyst. The results revealed that fine-sized TiO2 and CuO nanoparticles were uniformly and tightly loaded on the montmorillonite layers. The photocatalytic properties of the photocatalyst were evaluated using sodium butyl xanthate as the target contaminant. For pristine TiO2, ultraviolet (UV) light was required to effectively degrade sodium butyl xanthate. Meanwhile, the degradation reaction could be processed efficiently under visible light using the TiO2/CuO/montmorillonite composite as the photocatalyst. Moreover, UV–visible diffuse reflectance spectroscopy, photoluminescence spectroscopy, and radical quench experiments were performed to elucidate the degradation process, and a possible degradation model and mechanism were proposed.

Characterization of zinc oxide and graphitic carbon nitride nanocomposites for use as a potential photoelectrode

In this research, two nanocomposites of zinc oxide and graphitic carbon nitride were obtained in a 1:0.15 ratio for potential use as photoelectrocatalysts. Calcination and the simple reflux method were used to obtain routes for synthesizing zinc oxide and graphitic carbon nitride nanocomposites. Subsequently, Fourier transform infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, and Raman spectroscopy analyses were performed, from which it was determined that there is a strong interaction between zinc oxide and graphitic carbon nitride in both nanocomposites. Nevertheless, the nanocomposite that exhibited the most significant band gap reduction was obtained by calcination, reaching 2.93 eV.

Evaluation of sol-gel and solvothermal method on titanium dioxide and reduced graphene oxide nanocomposite

The present study compares two synthesis routes to obtain titanium dioxide and reduced graphene oxide nanocomposites that could be used as photoelectrodes in a water-splitting photoelectrocatalytic system. The nanocomposites were obtained using in-situ sol-gel and solvothermal methods as fabrication routes. Subsequently, the materials obtained were characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, and ultraviolet-visible diffuse reflectance spectroscopy techniques. The results indicated a strong interaction between reduced graphene oxide and titanium dioxide nanomaterials using both synthesis processes; however, the in-situ sol-gel method exhibited more significant conservation of the aromatic rings of the graphene structure and a lower bandgap (2.45 eV), which are suitable characteristics for its potential use in photoelectrocatalytic processes.