Diffuse Reflectance Spectroscopy Research Articles

Ti3AlC2 MAX/MXene for Hydrogen Generation via Photocatalytic Hydride Hydrolysis

Reducing dehydrogenation temperature while preserving high hydrogen generation capacity obstructs the hydrolysis of sodium borohydrides (NaBH4). The two-dimensional (2D) MAX phase of titanium aluminum carbide (Ti3AlC2) and MXene (Ti3C2Tx) multilayers was investigated for hydrogen generation via NaBH4 hydrolysis with and without light. The material was characterized using X-ray diffraction (XRD), Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), scanning electron microscopy (SEM), and diffuse reflectance spectroscopy (DRS). The activity of Ti3AlC2 was significantly enhanced by the integration of UV light radiation during hydrolysis. Ti3AlC2/Ti3C2Tx improved the dehydrogenation rates of NaBH4 at ambient conditions and maintained high hydrogen generation rates (HGRs) over time compared to a conventional method. It exhibited a HGR of 200–300 mL·min−1·g−1. Photo-assisted hydrolysis over the catalyst can be maintained for several times at ambient temperature. The catalyst demonstrated effective performance even after five cycles of usage.

Discriminating the adulteration of varieties and misrepresentation of vintages of Pu’er tea based on Fourier transform near infrared diffuse reflectance spectroscopy

In the Pu’er tea market, the ubiquity of blending different varieties and the fraudulent representation of vintage years present a persistent challenge. Traditional sensory evaluation and experience are often inadequate for discerning the true variety and vintage of tea, highlighting the need for more sophisticated analytical methods to ensure authenticity and quality. Fourier transform near infrared diffuse reflectance spectroscopy combined with radial basis function neural network (RBFNN) was applied for determination of the varieties and vintages of Pu’er tea. For vintage identification, the accuracy, precision, recall, and F1-score of the RBFNN model for the prediction set were 99.2%, 98.2%, 98.0%, and 98.0%, respectively. For identification of varieties adulteration, the corresponding parameters were 98.9%, 97.2%, 96.7%, and 96.6%, respectively. These results illustrated the feasibility to identify the adulteration of varieties and misrepresentation of vintages of Pu’er tea with near infrared spectra and RBFNN model, proving an efficient alternative for Pu’er tea quality inspection, and offering a robust method for combating the pervasive issues within the market.

Microstructural, magnetic, dielectric, and optical studies of La‐doped Sr2Fe0.5Hf1.5O6 double perovskite oxides

AbstractHerein, we report on the structural, magnetic, dielectric, and optical properties of La‐doped Sr2‐xLaxFe0.5Hf1.5O6 (SLFHO, 0.0 ≤ x ≤ 2.0) double perovskite oxides synthesized by solid‐state reaction method. X‐ray powder diffraction data and their Rietveld refinement reveal that the SLFHO powders crystallize in an orthorhombic structure with the Pnma space group. The SLFHO powders exhibit spherical morphology with an average particle size of 160 nm, as shown from SEM images. Their molar ratios of the Sr:La:Fe:Hf elements were determined as 1.77:0.50:0.50:1.95 by energy dispersive X‐ray spectroscopy data, approaching their nominal stoichiometry. X‐ray photoelectron spectra verified that Sr2+, La3+, Fe3+, and Hf4+ (Hfx+) ions existed in the SLFHO powders, and oxygen existed in species lattice oxygen and adsorbed oxygen, respectively. The SLFHO powders exhibit ferromagnetic behavior at 2 and 300 K, respectively, and at 2 K the saturated magnetization was 5.66 emu/g (or 0.60 μB/f.u.). Magnetic transition temperature, TC was determined to be 867 K. Dielectric measurements demonstrated a strong frequency‐dependent dielectric behavior observed in the SLFHO ceramics and a relaxor‐like dielectric behavior appearing in the temperature range of 200–600 K. Such relaxor‐like dielectric behavior is ascribed to the dielectric response of the singly‐ionized oxygen vacancies ( an activation energy of 0.54 eV. Room temperature optical properties of the SLFHO powders examined by using UV–vis diffuse reflectance spectroscopy exhibit high optical absorption in this wavelength region, and a wide indirect optical bandgap (Eg = 3.39 eV) was estimated using the Tauc's relation from the diffuse reflectance spectra. The SLFHO double perovskite oxides display high‐temperature ferrimagnetism, relaxor‐like dielectric behavior, and wide optical bandgap, making them potential to be employed in the fields of high‐temperature spintronics and magnetic semiconductor devices.

Identifying the color and absorption band properties of Fe oxides in Danxia red beds by the visible diffuse reflectance spectrum

This study investigates the Danxia Basin, the place where Danxia landforms were first named, by employing diffuse reflectance spectroscopy to analyze samples from various hue sequences of red beds. The colors of the Danxia red beds were precisely and quantitatively analyzed using the CIE color space and the Munsell color system. The raw spectra of the samples were then transformed using the second derivative of the Kubelka–Munk function and continuum removal techniques to perform spectral analysis, aiming to elucidate the absorption characteristics of Fe oxides and their influence on the coloration of the Danxia red beds. The results show that the Munsell hues of the Danxia red beds span from 6.5R to 9YR, while powdered samples exhibit a slight yellow shift, ranging from 2.5YR to 0.1Y, with increased chroma and significantly higher lightness. Fe oxides display three main absorption bands in the visible spectrum: (4E; 4A1) ← 6A1, 4T2 ← 6A1, and 2(4T1) ← 2(6A1) (EPT). Among these, the EPT band plays a pivotal role in determining the color. Since the Fe oxides in the Danxia red beds are predominantly composed of hematite with minor goethite, the EPT (Hem) absorption band is the most prominent, occurring between 526 and 544 nm. While the CIE color space offers superior precision for color measurement and analysis, the Munsell system provides ease of description. Therefore, a combination of both systems is recommended for practical applications.

Refining thyroid function evaluation: a comparative study of preprocessing methods in diffuse reflectance spectroscopy

Thyroid dysfunction, comprising conditions such as hyperthyroidism and hypothyroidism, represents a substantial global health challenge, necessitating timely and precise diagnosis for effective therapeutic intervention and patient welfare. Conventional diagnostic modalities often involve invasive procedures, that could cause discomfort and inconvenience for individuals. The non-invasive techniques like diffuse reflectance spectroscopy (DRS) can offer a promising alternative. This study underscores the critical role of preprocessing methods in enhancing the accuracy of thyroid hormone functionality through a non-invasive approach. In the proposed study the spectral data acquired from the DRS setup are subjected to different preprocessing techniques to improve the efficacy of the prediction model. Thirty individuals with thyroid dysfunction were included in the study, and preprocessing methods such as baseline correction, multiplicative scatter correction (MSC), and standard normal variate (SNV), were systematically evaluated. The study highlights that SNV preprocessing outperformed other methods with a root mean square error (RMSE) of 0.005 and an R² of 0.99. In contrast, MSC resulted in an RMSE of 0.87 and an R² of 0.86, while baseline correction showed a RMSE of 0.84 and an unusual R² of 1.09, indicating potential issues. SNV proved to be the most effective technique.

Insights into the expeditious photocatalytic performance of greenly fabricated CeVO4 nanoparticles using Polyalthia longifolia leaf extract

The application of nanomaterials to address environmental challenges has evolved substantially to eliminate pollutants from wastewater as part of environmental cleanup, a growing important research arena. Using green photocatalysts is a noteworthy and economical method that significantly advances environmentally sustainable remediation. This work disclosed the bio-inspired production of cerium vanadate nanoparticles (CeVO4 NPs) were prepared through a green chemistry protocol employing Polyalthia longifolia leaf extract. Key traits of CeVO4 nanoparticles were determined by applying a variety of characterization tools, including X-ray diffraction (XRD), Raman, Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible diffuse reflectance spectroscopy (UVDRS), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), and high-resolution transmission electron microscopy (HRTEM). CeVO4 nanoparticles displayed a pseudo-spherical topology with a particle size of 17.77 nm, and the band gap was determined as 2.76 eV. The photocatalytic ability of the as-produced CeVO4 NPs was scrutinized for the decomposition of Congo red (CR) dye. Under optimal conditions, the fabricated CeVO4 nanoparticles demonstrated excellent Congo red dye degradation performance. The effect of hydrogen peroxide (H2O2) dosage, nanoparticle dosage, dye concentration, contact time, scavenging test, and reusability of prepared photocatalyst had an excellent impact on dye decomposition ability. The findings revealed that in just 8 min, 97.79 % of the CR dye had been degraded completely. The pseudo-first-order (PFO) kinetics model aligns with the CR dye decomposition kinetics. In conclusion, this study describes the fabrication of a CeVO4 photocatalyst that exhibits impressive performance, particularly in natural sunlight, suggesting that it could be used in wastewater treatment.

Bismuth Vanadate Microspheres: Utilizing Temperature-driven Phase Transition for Improved Sunlight-Driven Photocatalysis and Antibacterial Efficacy

In this work, bismuth vanadate (BiVO4) microspheres are synthesized using a simple, cost effective, co-precipitation technique. This study investigates how the annealing temperature influences the photocatalytic and antimicrobial properties of nanoparticles made of BiVO4. Examining the phase structure, chemical compounds state, composition of chemicals, shape, as well as optical characteristics of the prepared materials, by using X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), Raman analysis, UV-Vis diffuse reflectance spectroscopy (DRS), Photoluminescence (PL) spectroscopy studies. Based on XRD analysis data, BiVO4 exhibits a phase change of the tetragonal structure to monoclinic at 500 °C (BiVO4@500 °C). It is interesting to note that under sunlight irradiation, BiVO4 nanoparticles annealed at 500 °C show excellent photocatalytic behavior in opposition to the dye methylene blue (k = 0.0151 min-1). According to investigations on the development of antibacterial activity through the utilization of BiVO4@500 °C sample by well diffusion method appears to be an effective growth inhibitor of both gram-positive and gram-negative bacteria, such as Bacillus subtilis (B. subtilis), Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Proteus vulgaris (P. vulgaris)), respectively.

Characterisation and visible light induced antibacterial activity of Cu-doped zinc oxide nanoparticles

ABSTRACT Zinc oxide particles doped with copper were produced using a cost-effective sol-gel approach at a temperature of 80°C. The process involved combining Zn(NO3)2, Cu(NO3)2, and citrate precursors. A variety of analytical techniques, including scanning electron microscopy, Energy-dispersive X-ray spectroscopy (EDX), diffuse reflectance spectroscopy (UV-Vis DRS), and energy dispersive X-ray diffraction spectroscopy (XRD), were employed to study the physical and chemical characteristics of the nanoparticles. The addition of copper resulted in a significant decrease in the size of wurtzite ZnO nanoparticles, reducing from 180 nm for undoped ZnO to 133 and 40 nm for 10% Cu-doped and 25% Cu-doped ZnO, respectively. The absorption spectra displayed a gradual shift towards the visible range as the concentration of copper in the ZnO particles increased. The calculated band gaps for the various samples were determined to be 3.1 eV for undoped ZnO, 2.3 eV and for 10% Cu-doped ZnO, and 1.8 eV for 25% Cu-doped ZnO. The antibacterial efficacy of Cu-doped ZnO was observed to be significantly greater than that of the undoped sample. Additionally, it demonstrated antibacterial activity under visible light conditions, which suggests the successful synthesis of zinc oxide particles that are induced by visible light.

Enhanced photocatalytic degradation of Rhodamine B using polyaniline-coated XTiO3(X = Co, Ni) nanocomposites

In this study, novel polyaniline-coated perovskite nanocomposites (PANI@CoTiO3 and PANI@NiTiO3) were synthesized using an in situ oxidative polymerization method and evaluated for the photocatalytic degradation of Rhodamine B (RhB) a persistent organic pollutant. The nanocomposites displayed significantly enhanced photocatalytic efficiency compared to pure perovskites. The 1%wt PANI@NiTiO3 achieved an impressive 94% degradation of RhB under visible light after 180 min, while 1wt.% PANI@CoTiO3 reached 87% degradation under UV light in the same duration. X-ray diffraction (XRD) confirmed that the crystalline structures of CoTiO3 and NiTiO3 remained intact post-polymerization. At the same time, Fourier transform infrared spectroscopy (FTIR) verified the successful deposition of PANI through characteristic functional group vibrations. Diffuse reflectance spectroscopy (DRS) revealed reduced band gaps of 2.63 eV for 1wt.% PANI@NiTiO3 and 2.46 eV for 1wt.% PANI@CoTiO3, enhancing light absorption across UV and visible ranges. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analysis demonstrated the uniform distribution of PANI, ensuring consistent surface activity and efficient charge transfer. The photocatalytic test confirmed a pseudo-first-order degradation mechanism. The study elucidates the degradation mechanism through intermediate identification via HPLC-MS analysis, highlighting N-de-ethylation, aromatic ring cleavage and eventual mineralization into CO2 and H2O as critical pathways. Furthermore, the 1wt.%PANI@NiTiO3 nanocomposite demonstrated excellent stability and recyclability, maintaining its degradation efficiency over four consecutive cycles with minimal change. These findings highlight the potential of PANI@XTiO3 nanocomposites for sustainable and efficient wastewater treatment, addressing diverse environmental challenges by tailoring photocatalysts to specific light sources.

Effect of Fe doping on structural, optical and magnetic properties of CdS quantum dots

Abstract Pure CdS nanoparticles and Fe-doped CdS quantum dots (Cd₁₋ₓFeₓS, where x = 0.0, 0.03, 0.06, 0.09, and 0.12) were successfully synthesized using the co-precipitation method. X-ray diffraction (XRD) analysis confirmed the cubic phase structure of CdS without additional peaks, indicating the effective incorporation of Fe ions into the CdS lattice. The crystallite size exhibited a gradual increase with increasing Fe content. High-resolution transmission electron microscopy (HR-TEM) revealed a well-defined spherical morphology for pure CdS, while Fe doping induced notable agglomeration in the quantum dots. X-ray photoelectron spectroscopy (XPS) confirmed the formation of the CdFeS composition and provided insights into the valence states of Cd, Fe, and S. UV-Vis diffuse reflectance spectroscopy (DRS) demonstrated a decrease in the optical band gap from 2.29 eV to 2.18 eV with Fe doping, indicating a modification of the electronic structure. Magnetization studies revealed a transition from diamagnetic behavior in pure CdS to ferromagnetic behavior in Fe-doped samples. Additionally, Fe doping significantly influenced the magnetic parameters, including saturation magnetization, remanence, and coercivity. These results highlight the structural, optical, and magnetic properties of CdS can be tuned through Fe doping, making these materials promising candidates for optoelectronic and spintronic applications.
Keywords: CdS quantum dots, XRD, XPS, optical energy gap, ferromagnetism.

Empowering wastewater treatment with step scheme heterojunction ternary nanocomposites for photocatalytic degradation of nitrophenol

The ongoing challenge of water pollution necessitates innovative approaches to remove organic contaminants from wastewater. In this work, new two-dimensional S-scheme heterojunction photocatalysts Bi2O3/CdS and MoS2/Bi2O3/CdS that are intended for the effective photocatalytic destruction of 4-nitrophenol, a dangerous organic pollutant, are synthesized and characterized. Utilizing a solvothermal method, successfully generated these ternary nanocomposites, which were characterized through various techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), high resolution transmission electronmicroscopy (HRTEM), Brunauer-Emmett-Telle (BET) and diffuse reflectance spectroscopy (DRS). Our results demonstrated that the Bi2O3/CdS heterojunction achieved an 86% degradation rate of 4-nitrophenol, while the MoS2/Bi2O3/CdS composite exhibited exceptional photocatalytic performance, achieving nearly complete degradation (99%) within 120 min under visible light irradiation. Most importantly the improved photocatalytic activity of MoS2/Bi2O3/CdS heterojunction originated from the release of internal electric field in S-scheme heterojunction. This enhanced activity is attributable to the synergistic effects of the heterojunctions that facilitate more effective charge separation and generation with more OP and RP confirmed the composite synthesis using S-scheme. The S-scheme is further confirmed by XPS, DRS, XPS-VB and photocurrent response. These findings highlight the promising application of these advanced photocatalysts in real-world wastewater treatment processes, offering a sustainable solution to combat water pollution.

Hierarchically Porous Titanosilicate Hollow Spheres Containing TS-1 Zeolite Precursors for Oxidative Desulfurization

The environmental and health impacts of sulfur compounds in fuel oil have prompted considerable research interest in oxidative desulfurization (ODS) technology. Tetrahedrally coordinated titanium has been demonstrated to exhibit excellent activity in the context of oxidative desulfurization processes. However, further improving the catalytic property of the tetrahedrally coordinated titanium remains a challenging endeavor. In the context of ODS processes conducted at near room temperatures, the improvement of conversion remains a subject of considerable challenge. In this study, hierarchically porous titanosilicate hollow spheres were synthesized by using TS-1 zeolite precursors as Ti and Si sources to obtain the catalyst with only tetrahedrally coordinated titanium. The synthesized materials were characterized through transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), ultraviolet–visible diffuse reflectance spectroscopy (UV-Vis), and nitrogen adsorption analysis. These techniques confirmed the formation of hollow spherical hierarchically porous structures with Ti species uniformly incorporated in tetrahedral coordination and the presence of five-member rings of TS-1 zeolite. As a result, the hierarchically porous titanosilicate hollow spheres demonstrated excellent catalytic performance in ODS, achieving complete dibenzothiophene (DBT) removal within 15 min and a high turnover frequency (TOF) of up to 123 h−¹ at 30 °C.

Optical Based Methods for Water Monitoring in Biological Tissue.

Skin homeostasis is strongly dependent on its hydration levels, making skin water content measurement vital across various fields, including medicine, cosmetology, and sports science. Noninvasive diagnostic techniques are particularly relevant for clinical applications due to their minimal risk of side effects. A range of optical methods have been developed for this purpose, each with unique physical principles, advantages, and limitations. This review provides an in-depth examination of optical techniques such as diffuse reflectance spectroscopy, optoacoustic spectroscopy, optoacoustic tomography, hyperspectral imaging, and Raman spectroscopy. We explore their efficacy in noninvasive monitoring of skin hydration and edema, which is characterized by an increase in interstitial fluid. By comparing the parameters, sensitivity, and clinical applications of these techniques, this review offers a comprehensive understanding of their potential to enhance diagnostic precision and improve patient care.

Selective hydrogenation of anisole over Pt/SBA-15 catalysts: Effect of Pt loading on catalytic efficiency

Abstract Pt catalysts (0.1–2 wt.% of platinum) supported on SBA-15 were used for the selective hydrogenation of the aromatic ring of anisole with the formation of cyclohexyl methyl ether product. The catalysts were characterized by N2 physisorption, UV–vis diffuse reflectance spectroscopy, powder X-ray diffraction, and scanning and transmission electron microscopies. The reaction progress and the impact of Pt loading in the catalysts were analyzed by gas chromatography. All the catalysts demonstrated high catalytic activity for the hydrogenation of anisole to cyclohexyl methyl ether (CME), reaching 90–98% anisole conversion at 6-h reaction time with near 90% selectivity to CME (280 °C, 6.9 MPa total pressure). An increase in the Pt content led to a slight decrease in the selectivity to CME due to its transformation to cyclohexane. 1%Pt/SBA-15 catalyst was tested in three repeated catalytic cycles showing high stability and preservation of Pt nanoparticle dispersion. Graphical abstract

Sex and age-related day-to-day variability in the skin microcirculation during post-occlusive reactive hyperemia.

Little is known about the day-to-day variability of different skin microcirculation parameters, and how this variability is influenced by age and sex. The aim was to examine the day-to-day variability of microcirculatory parameters in relation to age and sex. The cutaneous microcirculation was measured using a fiber optic probe integrating laser Doppler flowmetry (LDF) and diffuse reflectance spectroscopy (DRS) to measure oxygen saturation, red blood cell (RBC) tissue fraction, speed-resolved and conventional perfusion. Measurements at two separate days were compared during baseline, a 5-min occlusion and during the following post-occlusive reactive hyperemia (PORH) period on the volar forearm and dorsal foot in totally 48 men and women aged 20-30 and 50-60 years, respectively. Variability was expressed as the coefficient of variation CV and repeatability as the intraclass correlation coefficient ICC. Peak oxygen saturation during PORH had the lowest day-to-day variability for the forearm (CV = 2.1 %) and the foot (CV = 3.8 %) as well as an excellent repeatability (ICC = 0.80 and ICC = 0.82, respectively). Older women had a higher day-to-day variability in baseline conventional perfusion compared to younger women on the forearm (p = 0.007). On the foot, older women had a lower day-to-day variability than younger women for baseline oxygen saturation (p = 0.006) and peak RBC tissue concentration (p = 0.008). Older men had a lower day-to-day variability than younger men for baseline oxygen saturation (p = 0.012) but a higher variability for baseline and peak RBC tissue concentration (p = 0.008 and p = 0.002) on the foot. Peak oxygen saturation had the lowest day-to-day variability of the measured parameters. A lower value of peak oxygen saturation has previously been associated with increasing systematic coronary risk implying that this is a suitable parameter for measuring microcirculatory dysfunction. Sex and age only affected the day-to-day variability of very few parameters.

Evaluation of Mechanochemically Prepared CePO4∙H2O Nanoparticles as UV Filter for Photoprotective Formulations.

Rhabdophane, CePO4∙H2O, nanoparticles were prepared by mechanochemical synthesis with different durations and thoroughly characterized by various characterization techniques. X-ray diffraction analysis showed that the optimal synthesis duration was 15 min, since, in this case, pure rhabdophane is obtained, without traces of contamination by the vessel material. The size of the obtained nanoparticles, as determined from high-resolution transmission electron microscopy images, was around 5 nm. According to UV-Vis diffuse reflectance spectroscopy results, rhabdophane nanoparticles show transparency to visible light and high absorption in the UV region, with a direct bandgap of 3.1 eV. The photocatalytic activity in the Castor oil degradation process and the cytotoxicity for human skin cells were determined and compared to commercial TiO2 nanoparticles, with rhabdophane nanoparticles exhibiting superior properties. Small particle size, purity, absorption in the UV range, transparency to visible light, low photocatalytic activity, and low cytotoxicity indicated the possibility of prepared rhabdophane application as an inorganic UV filter in photoprotective formulations.

Reversible phase transition and tunable band gap in zinc telluride induced by acoustic shock exposure.

In this study, Zinc Telluride (ZnTe) was subjected to acoustic shock waves with a Mach number of 1.5, transient pressure of 0.59 MPa, and a temperature of 520 K to analyze its stability against shock wave impact. ZnTe was exposed to different shock pulses, such as 100, 200, 300, and 400. The stability was assessed through multiple characterization techniques such as Powder X-ray diffraction (PXRD), Raman spectroscopy, Ultraviolet diffuse reflectance spectroscopy (UV-DRS) analysis, Photoluminescence (PL) spectroscopy, and Scanning Electron Microscopy (SEM). The X-ray diffraction pattern revealed a phase transition at 300 shock pulses from cubic (F4̄3m) to cubic (Fm3̄m). Interestingly, at 400 shock pulses, the original cubic (F4̄3m) phase was restored. The Raman spectrum showed the disappearance, intensity variation, and shift of Raman peaks, particularly at 300 shock pulses, which reverted to the original state at 400 pulses, indicating a reversible phase transition. The absorption spectrum exhibited a lower angle shift and a change in band gap from 2.85 eV to 2.63 eV at 300 shock pulses. However, the band gap was reduced to 2.8 eV at 400 shock pulses. The photoluminescence spectrum showed high intensity specifically at 300 shock-loaded conditions. Morphological analysis revealed a change from irregular shapes to plate-like structures at 300 shock pulses. The results confirm that shock waves significantly impact ZnTe, inducing a reversible phase transition.

Electrochemical and physical properties of magnesioferrite nanomaterial and photocatalytic degradation of methylene blue

This research successfully synthesized semiconductive magnesioferrite (MgFe2O4) nanomaterials using a green chemistry method that utilizes the natural extract of Moringa olefeira serving as both a reducing and oxidizing agent. The optical characteristics and crystalline structure of the MgFe2O4 nanomaterials were analysed using photoluminescence, diffuse reflectance spectroscopy, and X-ray diffraction. Additionally, Fourier transform infrared spectroscopy provided valuable insights into the chemical bonding and composition. High-resolution transmission electron microscopy was employed to obtain extensive information on crystalline size and distribution. Furthermore, the electrochemical properties were assessed through cyclic voltammetry and electrochemical impedance spectroscopy, revealing an excellent voltametric response and pseudo-capacitive behaviour associated with faradaic reactions, as well as outstanding conductivity linked to the unique charge transport mechanisms present in the MgFe2O4 structure. The effectiveness of the MgFe2O4 nanomaterials in the photodegradation of methylene blue from aqueous solutions was evaluated under visible light irradiation. Photocatalytic experiments measured the influence of various parameters, including catalyst loading, dye concentration, and pH. The MgFe2O4 nanomaterials exhibited impressive photocatalytic degradation efficiency, achieving an 81% degradation rate at pH 5.0 within 120 min. Kinetic studies indicated that the degradation process adhered to a pseudo-first-order model, with a rate constant of 0.01533 min−1, signifying a rapid reaction under optimal conditions. This study provides a thorough understanding of the electrochemical properties and enhanced photocatalytic capabilities of MgFe2O4 nanomaterials, thereby advancing green nanotechnology for environmental remediation.

Sol-Gel Synthesis of TiO2 from TiOSO4 (Part 2): Kinetics and Photocatalytic Efficiency of Methylene Blue Degradation Under UV Irradiation

The sol-gel process was used to create titanium dioxide (TiO2) nanoparticles, a nanocrystalline semiconductor. How several synthesis factors, such as titanium precursor concentration, annealing temperature, and peptization temperature, affected the structural and morphological properties of TiO2 nanoparticles were thoroughly explored. X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), measurements of the specific surface area and pore size using the BET method, and UV-visible diffuse reflectance spectroscopy were all used in this investigation. The specific surface area determined by BET analysis decreased with increasing calcination temperature. The XRD analysis showed that a composite sample consisting mainly of anatase with minor brookite phases was obtained when the titanium precursor concentration ranged between 0.2 and 0.4 M, whereas a concentration of 0.5 M resulted in the formation of pure anatase. The photocatalytic activity of the synthesized TiO2 powders under different operational parameters was evaluated for the common commercial textile dye, i.e., methylene blue (MB). It was experimented that the model pollutant decoloration follows the Langmuir–Hinshelwood (L-H) model. In view of this detailed research work, it was observed that the TiO2 produced with a titanium precursor concentration of 0.3 M, a pH value of 5 during the peptization step, and an annealing temperature of 600 °C were found to be the best conditions for this catalytic degradation process. When used in conjunction with a TiO2 concentration of 0.04 g/L and a reactor suspension pH value of 6.0, the TiO2 catalyst produced a stunning 98% degradation of methylene blue under these circumstances.

Visible-Light-Driven Degradation of Chloramphenicol Using CeO2 Nanoparticles Prepared by a Supercritical CO2 Route: A Proof of Concept.

Recently, the extensive use of antibiotics has unavoidably resulted in the discharge of significant quantities of these drugs into the environment, causing contamination and fostering antibiotic resistance. Among various approaches employed to tackle this problem, heterogeneous photocatalysis has emerged as a technique for antibiotic degradation. This study explores the potential of CeO2 as a photocatalyst for the degradation of chloramphenicol. Supercritical antisolvent (SAS) processing was successfully employed to synthesize photocatalyst precursor nanoparticles. After thermal annealing, the CeO2 samples were characterized through UV-Vis diffuse reflectance spectroscopy to evaluate the band gap energy values. Raman and FT-IR spectroscopy confirmed the presence of oxygen vacancies in the CeO2 lattice. During photocatalytic experiments, the CeO2 derived from the SAS-processed precursor exhibited superior photocatalytic performance compared to the catalyst synthesized from the non-micronized precursor. Various annealing temperatures were employed to tune the oxygen vacancy of CeO2. Furthermore, the impact of catalyst dosage and chloramphenicol concentration was investigated. Under optimal reaction conditions (25 mg L-1 chloramphenicol and 2.25 g L-1 catalyst dosage), a degradation efficiency of 64% was achieved. Finally, to elucidate the degradation mechanism, different scavengers (EDTA, benzoquinone, and isopropyl alcohol) were utilized, revealing that the superoxide radical is the primary species responsible for chloramphenicol degradation.