UV Vis Diffuse Reflectance Research Articles

Understanding of the effect of concentration of green polysaccharide-based TiO2 for photoelectrochemical, photocatalytic, and antibacterial properties

Composites formed by TiO2/babassu mesocarp were synthesized by the sol-gel method with a percentage variation of 3 % and 5 % (w/v) called 3BBT and 5BBT, respectively. The materials were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), UV–Vis Diffuse Reflectance Spectroscopy, and surface area was calculated by the Brunauer–Emmett–Teller method (BET). Electrochemical studies were carried out, and photocurrent data was obtained as a function of the variation in gallic acid concentration and applied potential. The photocatalytic efficiency of the material was investigated by the degradation of the Methylene Blue (MB) dye under light. The antimicrobial activity of the materials was tested on Gram-positive and Gram-negative strains. XRD showed that the composites obtained are in the anatase crystallographic phase, and the increase in the percentage of babassu mesocarp influenced the reduction of peak intensity and crystallite size. The microscopy showed a more porous aspect of the 3BBT material and a denser aspect of the 5BBT material. It was confirmed by textural characterizations, which showed reduced pore volume and specific surface area of 5BBT compared to 3BBT. Increasing the percentage of polysaccharides caused a reduction in the band gap energy of TiO2 (Eg = 2.90 eV and Eg = 2.47 eV for 3BBT and 5BBT, respectively). The electrochemical study showed that the composites could detect gallic acid, providing increased sensitivity according to the increased applied photocurrent. They also showed good precision for the photoelectrochemical measurements, as verified in the repeatability test (2.66 % and 3.68 % RPD for 3BBT and 5BBT, respectively). The 3BBT showed greater photocatalytic capacity, discoloring 63.4 % of the MB dye in 120 min under light and electrons are the main species involved in photocatalytic activity demonstrated by 3BBT. Antibacterial tests indicated that the 5BBT material exhibits a greater capacity to inhibit E. coli and S. aureus bacteria.

Preparation of pigmentary grade bismuth vanadate Bi4V2O11 via coprecipitation method

ABSTRACT In this study, Bi4V2O11 pigments were synthesized using a coprecipitation method, and the pH value and calcination temperature were optimized from the viewpoint of red colorant. The obtained samples were characterized by XRF, XRD, Rietveld refinement, TEM, UV–vis diffuse reflectance spectrometry, SEM, XPS and color measurements. It was found that Bi4V2O11 samples with single-phase monoclinic structure could be prepared, when the calcination temperatures were 973 and 1073 K. The obtained single-phase Bi4V2O11 samples exhibited reddish hue. For the sample, which was prepared at pH = 7.0 and calcined at 973 K, its color coordinates were L* = 46.41, a* = +27.41, b* = +26.09.

Extended Interfacial Charge Transference in CoFe2O4/WO3 Nanocomposites for the Photocatalytic Degradation of Tetracycline Antibiotics.

The large-scale utilization of antibiotics has opened a separate chapter of pollution with the generation of reactive drug-resistant bacteria. To deal with this, in this work, different mass ratios of CoFe2O4/WO3 nanocomposites were prepared following an in situ growth method using the precursors of WO3 and CoFe2O4. The structure, morphology, and optical properties of the nanocomposite photocatalysts were scrutinized by X-ray diffraction (XRD), UV-visible diffuse reflectance spectra (UV-Vis DRS), photoluminescence spectrum (PL), etc. The experimental data signified that the loading of CoFe2O4 obviously changed the optical properties of WO3. The photocatalytic performance of CoFe2O4/WO3 composites was investigated by considering tetracycline as a potential pollutant. The outcome of the analyzed data exposed that the CoFe2O4/WO3 composite with a mass ratio of 5% had the best degradation performance for tetracycline eradication under the solar light, and a degradation efficiency of 77% was achieved in 20 min. The monitored degradation efficiency of the optimized photocatalyst was 45% higher compared with the degradation efficiency of 32% for pure WO3. Capturing experiments and tests revealed that hydroxyl radical (·OH) and hole (h+) were the primary eradicators of the target pollutant. This study demonstrates that a proper mass of CoFe2O4 can significantly push WO3 for enhanced eradication of waterborne pollutants.

Synthesis of corn straw based carbon doped Nb2O5 as photocatalysts for Rhodamine B degradation under visible light illumination

Developing efficient visible light photocatalytic materials has always been a challenge for researchers. We have successfully prepared a series of corn straw based carbon doped Nb2O5 with excellent photocatalytic performance under visible light. A series of characterizations were carried out on the synthesized materials, including power X-Ray diffraction (XRD), scan electron microscopy (SEM), nitrogen adsorption, UV–vis diffuse reflectance spectra, X-ray photoelectron spectroscopy (XPS). The photocatalytic performance of the synthesized samples was investigated under visible light irradiation using Rhodamine B as the degradation target. Under visible light irradiation for 30 min, C/Nb2O5 can decompose Rhodamine B by 97.1 %, and the photocatalytic performance remains unchanged after 5 cycles. In the article, the contributions of three active substances involved in the photodegradation of Rhodamine B were studied through scavenger study, and the mechanism of C/Nb2O5 photodegradation of Rhodamine B was analyzed. This research is of great significance for the application of biomass materials and the improvement of environmental quality, and also provides new ideas for designing and synthesizing new composite functional materials.

Enhanced hypersensitive (5D0→7F2) transition characteristics of Eu3+ doped β-Ga2O3 microrods

Exploring and realizing the luminescence characteristics of rare earth metal (RE) ions doped gallium oxide (Ga2O3) is crucial for developing optoelectronic device applications. The current research used the solid-state reaction approach to synthesize Ga2O3 microrods doped with various europium (Eu3+) concentrations (0.1, 0.2, 0.3, 0.5, 0.75, and 1 mol). X-ray diffraction (XRD) and Raman spectral analyses confirm the monoclinic structure of β-Ga2O3. The intensity of the Raman phonon modes decreased and a peak shift was observed for Eu:β-Ga2O3. The electron microscopy (SEM, TEM) images depicted a nearly uniform distribution of microrods for undoped and Eu:β-Ga2O3 samples. The interplanar distance (d = 0.290 nm, 0.561 nm, and 0.433 nm), from HR-TEM images, corresponding to (0 0 4), (1 0 0), and (1 0 2) crystallographic orientations confirm the monoclinic structure of β-Ga2O3. The elemental mapping images showed a nearly homogeneous Ga, O, and Eu distribution. The UV–visible diffuse reflectance spectroscopy (UV-DRS) showed a notable reduction in the bandgap as the Eu3+ concentration increased. The emission spectra of Eu: β-Ga2O3 microrods showed a narrow red emission at 612 nm (5D0 → 7F2), which relates to the 5D0 → 7Fj (j = 0, 1, 2, 3) energy level arising from an intra-4f transition of Eu3+ ions upon 394 and 465 nm excitation. The red emission was found to increase with Eu content up to 0.5 mol.%. A quenching of emission due to the multipole–multipole interactions was obtained beyond 0.5 mol.% of Eu. The absolute quantum yield (η) calculated for Eu: β-Ga2O3 (0.5 mol.%) was 3.82 %. The luminescence decay curve using the bi-exponential fit and the average lifetime (τ) of the Eu: β-Ga2O3 (0.5 mol.%) was found to be ∼0.172 ms. CIE chromaticity and correlated color temperature analyses of Eu:β-Ga2O3 microrods yielded a red emission with a superior color purity (93 %). The obtained results suggest that Eu:β-Ga2O3 (0.5 wt.%) microrods could be one of the potential candidates for red light sources.

Bioinspired synthesis of calcium magnesium aluminate nanoparticles using aloe vera extract: A promising material for electrochemical sensors, antibacterial and environmental remediation applications

Aloe vera (Aloe barbadensis miller) leaf extract was used in green fuel-assisted microwave synthesis to prepare Calcium Magnesium Aluminate (CMA). The synthesized CMA was characterized by X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), Scanning electron microscope (SEM), Energy dispersion spectrometer (EDAX), and Transmission Electron Microscopy (TEM) analyses. X-ray diffraction confirmed the formation of Ca2Mg2Al28O46. The UV–Vis diffuse reflectance (DRS) technique was employed to investigate its absorbance spectrum, and the band gap of CMA was found to be 4.9 eV. The CMA nanoparticles were used to design a sensing electrode for creatinine, enabling the determination of its concentration in human samples and heavy metals. Acid Orange-88 dye was degraded using CMA nanoparticles as a photocatalyst under UV irradiation. After dye degradation, treated water was used to grow Vigna radiata plants to test their suitability for seedling growth. This report demonstrates that CMA photocatalysts are alternatives to semiconductor photocatalysts for the degradation of Acid Orange-88 dye under UV illumination. Escherichia coli (E. coli), Staphylococcus species, and Pseudomonas species were used as model organisms to assess the antibacterial activity of CMA NPs through a green route.

Enhancement Study of the Photoactivity of TiO2 Photocatalysts during the Increase of the WO3 Ratio in the Presence of Ag Metal

Nanocomposites (NCs) consisting of 4%Ag/x%WO3/TiO2, with varied concentrations (x = 1, 3, 5, 7 wt.%) of WO3, were successfully synthesized using the sol-gel process to examine their photocatalytic performance. The synthesized 4%Ag/x%WO3/TiO2 nanopowder was characterized using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectra (UV–vis DRS), photoluminescence (PL), and Brunauer–Emmett–Teller (BET) surface area analysis to elucidate its physicochemical properties. The photocatalytic evaluation revealed that the Ag/1%WO3/TiO2 nanocomposite exhibits 98% photoreduction efficiency for Cr(VI) after 2 h under visible light due to the impact of the plasmonic effect of Ag atoms. In addition, the Ag/4%WO3/TiO2 shows about 95% photooxidation efficiency for methylene blue (MB) dye after 4 h.

Boosting photocatalytic efficiency and nonlinear optical response of graphitic carbon nitride by infusing carbon nanotubes

Nanostructured materials are widely studied for their light-driven physical and chemical processes, which are key to their potential in photophysical applications. We introduce a one-pot solid-state pyrolysis technique for the synthesis of graphitic carbon nitride/carbon nanotube (g-C3N4/CNT) composites. The formation of the composite was characterized through X-ray diffraction, scanning and transmission electron microscopy, and X-ray photoelectron spectroscopy. Notably, UV-vis diffuse reflectance spectroscopy indicated a reduction in the bandgap of pure g-C3N4 from 2.6 eV to 2.35 eV with the incorporation of 0.5 wt% CNT. The nonlinear optical transmission of the samples was analyzed at 532 nm using the open-aperture Z-scan technique employing 5 ns laser pulses, revealing a twelve-fold increase in the two-photon absorption coefficient (b) for g-C3N4/CNT0.5 compared to pristine g-C3N4. Remarkably, g-C3N4/CNT0.5 showed enhanced photocatalytic efficiency in degrading bisphenol A (BPA), with the kinetic constant (k) being ten times higher than that of pure g-C3N4. The improved photocatalytic performance of g-C3N4/CNT0.5 is attributed to the presence of CNTs, which act as effective electron acceptors and transfer channels, significantly enhancing the separation of photogenerated charge carriers in g-C3N4, as evidenced by the decreased intensity in the photoluminescence spectrum.

Shear strength and optical bandgap in As2Se3 glasses permanently compacted under GPa pressures

The application of GPa pressures on glassy As2Se3, at temperatures just below and above its glass transition, leads to permanently compacted glasses that exhibit increased densification. Also, melt-quenching of the same glass under a pressure of 7 GPa gives rise to the formation of its crystalline β-phase. The structure of these As2Se3 compacted solids have been explored by X-ray diffraction. Measurements of 10 MHz ultrasound velocities reveal that the density increase is associated with a substantial hardening of the elastic continuum as well as a growing shear strength of glassy solids: the shear modulus G increases by more than 35 % and the Poisson's ratio ν decreases by more than 13 %. The optical properties have been investigated by UV–VIS diffuse reflectance spectroscopy, which shows a well defined linear reduction of the optical bandgap Eg with increased density. All of these observations have been explained by considering a disordered layered structure of glassy As2Se3, where densification produced by compaction under GPa pressures gives rise to a progressive strengthening of the interlayer interactions.

Exploring the defect formation and ionic migration in A2Zr2O7 (A = La, Ce, Nd, and Gd) Pyrochlore solid-state electrolytes

This study investigated the potential of A2Zr2O7 pyrochlore phase oxides (A = La, Ce, Nd, and Gd) as solid oxide fuel cell (SOFC) electrolyte materials. A2Zr2O7 ceramics were synthesized using the sol-gel process, and their disordered pyrochlore structure was confirmed by X-ray Diffraction and Rietveld refinement. Field Emission Scanning Electron Microscopy (FE-SEM) was used to examine the morphology of the materials, while X-Ray Photoelectron Spectroscopy (XPS) confirmed a high oxygen ion concentration. UV–Vis Diffuse Reflectance Spectroscopy (DRS) and density of states calculations consistently showed similar bandgap patterns in all zirconate pyrochlore. Density Functional Theory (DFT) simulations provided insights into the electronic structure and migration pathways. A two-probe conductivity study confirmed the relation between the ionic conductivity and ordering degree of pyrochlore. At 750 °C, LZO, CZO, and GZO exhibited ionic conductivity values of 5.44 × 10−3 S/cm, 3.00 × 10−3 S/cm, and 2.01 × 10−3 S/cm respectively, while NZO demonstrated a conductivity of 1.27 × 10−2 S/cm at 700 °C, which is higher than that of the other samples. This study favours the use of the sol-gel route for processing zirconate pyrochlore materials, highlighting its ability to achieve high densities at lower temperatures and exhibit enhanced ionic conductivity. A2Zr2O7 has emerged as a promising oxide-ion conducting solid electrolyte for intermediate temperature SOFC applications within the 600–750 °C temperature range.

Z-scheme heterojunction of TiO2/NH2-MIL-125(Ti) growing on carbon fibers cloth: Photocatalytic degradation of tetracycline and toxicity analysis

Photocatalysis stands out as a promising and eco-friendly method for antibiotics removal, yet traditional photocatalysts, mainly in powder form, are often prone to detachment and loss, making them difficult to recycle and reuse. In this work, we address this challenge by using carbon fiber (CF) cloth with a large area as a carrier for catalysts. To improve the photocatalytic efficiency, we synthesized TiO2 nanorods on the surfaces of CF cloth and incorporate NH2-MIL-125 (Ti) on them, thus the Z-scheme heterojunctions CF/TiO2/NH2-MIL-125(Ti) was obtained. In order to fully understand the structural properties and performance advantages of CF/TiO2/NH₂-MIL-125 (Ti) composites, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray photoelectron spectroscopy (XPS), UV–visible diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), Brunauer-Emmett-Teller (BET), Mott-Schottky (M-S) and valence band X-ray photoelectron spectroscopy (VB-XPS). Due to the special electronic transmission path of the Z-scheme heterojunctions, the CF/TiO2/NH2-MIL-125(Ti) composite achieve 95.30 % degradation of tetracycline (TC) within 210 min. The composite also shows exceptional reusability, with a degradation rate of 93.55 % maintained even after four cycles. Finally, we proposed a pathway and catalytic process for the decomposition of TC by CF/TiO2/NH2-MIL-125(Ti) and performed toxicity assessments of TC and its precursors using T.E.S.T. software. This novel photocatalyst composite offers a green and efficient approach for treating antibiotic wastewater, presenting a significant advancement in environmental remediation strategies.

Green synthesis of TiO2@g-C3N4 nanocomposites for the photocatalytic degradation of pesticides and toxic organics present in water and wastewater

To address the environmental challenges caused by toxic organics in aquatic systems, photocatalytic degradation is a promising option. This study investigates the green synthesis of TiO2@g-C3N4 nanocomposites by coupling Titanium dioxide (TiO2) and graphitic carbon nitride (g-C3N4) in different mass ratios through solvothermal technique due to their photocatalytic properties. Leaf extract from the Ziziphus jujube plant was utilized as a green template making the synthesis environmentally friendly, utilizing renewable resources, and employing facile and cost-effective methods. The nanocomposites were characterized using various analytical techniques including UV–Vis Diffuse reflectance spectroscopy (UV–Vis DRS), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and energy dispersive X-ray spectroscopy (EDS) to analyze the structural and morphological properties. The wavelength ranged from 385 to 454 nm and band gap energies ranged from 3.22 to 2.73 eV for the synthesized materials. The pure green TiO2 showed the highest band gap energy while pure g-C3N4 showed the lowest band gap energy among the synthesized materials. The photocatalytic activity of the synthesized nanocomposites was evaluated through the degradation of Bisphenol A and Malathion pesticide under UV light irradiation. The results indicated 71 % degradation of Bisphenol A with the 50 % TiO2@g-C3N4 nanocomposites exhibiting 1.422 x 10-2 min−1 rate constant and 74 % degradation of Malathion degraded over 20 % TiO2@g-C3N4 which depicted rate kinetics of 1.022 x 10-2 min−1. Moreover, both showcased higher performance than the individual TiO2 and g-C3N4 nanostructured materials.

Investigation on luminescent characteristics of Tb3+/Dy3+co-doped boro-phosphate glass for cool white LED and radiation shielding applications

The Tb3+/Dy3+ co-doped Boro-Phosphate Glass (BPANZDyTb) was produced (40 B2O3 + 39P2O5 + 5 Al2O3 + 5 NaF + 10 ZnO + 0.5 Tb2O3 + 0.5 Dy2O3) using melt-quenching technique. X-ray diffraction measurements, Raman, and Fourier Transform Infrared were used to evaluate the structural behavior of the prepared glass. Powder-XRD spectra, in the 10–90° range showed that the prepared glass was amorphous. FTIR analysis reveals that the network contains a variety of structural groups, including B-O-B, BO4, BO, P-O, PO2, P-O-B, and PO4 units. The UV–visible diffuse reflectance spectroscopy was used to record and study the optical linear properties of Tb3+/Dy3+ co-doped Boro-Phosphate Glass (BPANZDyTb). The photoluminescence excitation peak was obtained at 348 nm. The emission peaks were located at 484 nm (4F9/2 → 6H15/2 → blue), 576 nm (4F9/2 → 6H13/2 → yellow), and 662 nm (4F9/2 → 6H11/2 → red). Tb3+ ions are located at 412 nm (5D3 → 7F5), 441 nm (5D3 → 7F4), 546 nm (5D4 → 7F5), and 625 nm (5D4 → 7F3). The result of CIE 1931 chromaticity coordinates indicate that the prepared glass is suitable material for cold white light emitting diode applications due to its color coordinates x = 0.3106 and y = 0.3240 and correlated color temperature (CCT) values about 6768 K. The gamma-ray parameters such as half-value layer (HVL), mass attenuation coefficient (μ/ρ), mean free path (MFP), and effective atomic number (Zeff) of the BPANZDyTb glass were studied using Phy-X software. The results of the gamma-ray parameter show that the Dy3+ ions and Tb3+ ions co-doped BoroPhosphate glass is an appropriate material for radiation shielding applications.

α-Bi2O3 tubular rods coated on Bi2O2CO3 nanosheets for high-performance asymmetric supercapacitor applications

Mixed phases of bismuth oxide nanostructures as an active electrode material in supercapacitor applications have recently gained huge research interest. In this study, the layered Bi2O2CO3 nanosheets and the secondary phase of α-Bi2O3 tubular rods named Bi2O2CO3/α-Bi2O3 heterostructure have been synthesized and utilized for supercapacitor applications. The crystal nature and microstructure of the Bi2O2CO3/α-Bi2O3 heterostructure were initially confirmed by powder X-ray diffraction (p-XRD), Raman, UV-Vis diffuse reflectance spectroscopy (UV-DRS, absorbance), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) studies. X-ray photoelectron spectroscopy (XPS) measurements have investigated the oxidation states and chemical binding energies. Regarding the electrochemical performances, the Bi2O2CO3/α-Bi2O3 heterostructure as electro-active material delivered a maximum specific capacitance (Cs) value of 635 F g−1 at the given current density value of 1 A g−1 in a conventional three-electrode mode. A coin cell type electrode has been fabricated using Bi2O2CO3/α-Bi2O3 heterostructure, resulting in an asymmetric supercapacitor device cell (ASC), which has a Cs of 112 F g− 1 (at 1 A g− 1) and a power density and energy density values of 515 W kg−1 and 22.5 Wh kg−1 respectively. The two supercapacitor electrodes in sequence effectively ignite the red-light-emitting diode (LED). Moreover, in the ASC type Bi2O2CO3 /α-Bi2O3 heterostructure, the specific capacitance value was slightly reduced to 12.3 % by 2000 cycles, showing favourable cyclic performance and stability during the electrochemical process. Based on the above-mentioned characterization, the appropriate electrochemical performances of Bi2O2CO3/α-Bi2O3 tubular rod heterostructures make them a promising candidate for future energy storage devices.

Constructing interfacial electric field with rich oxygen vacancy modulated heterojunction FeVO4-MgZnAl LDH for enhanced photocatalytic degradation of doxycycline

FeVO4 nanorods were synthesized and integrated with plate-like MgZnAl layered double hydroxide (MZA LDH) using a combination of sonochemical coprecipitation and hydrothermal methods. The resulting FeVO4-MgZnAl LDH nanocomposites (NCs) were engineered to enhance photocatalytic performance through an S-scheme charge transfer mechanism. These NCs exhibited exceptional photocatalytic activity, achieving 93.7 % degradation of doxycycline (DXY) which is significantly outperforming its counterparts, FeVO4 (29.8 %) and MgZnAl LDH (49.8 %). Detailed analysis using scavenging tests and electron spin resonance (ESR) analysis confirmed that the photoexcited charges follow the S-scheme pathway, leading to the generation of hydroxyl (•OH) and superoxide (O2•⁻) radicals. This mechanism remarkedly improves the catalytic efficiency of FeVO4-MZA NCs with a kinetic rate constant of 4–9 times higher than those of its individual components. The photocatalyst's were comprehensively characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–visible diffuse reflectance spectroscopy (UV–vis-DRS), photoluminescence (PL) spectroscopy, and electrochemical impedance spectroscopy (EIS). The FeVO₄-MZA NCs demonstrated remarkable stability and reusability, indicating their suitability for large-scale water treatment applications. Additionally, the non-toxic nature of FeVO4-MZA NCs, coupled with effective charge carrier separation and reduced recombination rates, establishes them as highly efficient photocatalysts for the removal of pharmaceutical contaminants from aquatic systems and paves a way for manufacturing innovation.

Construction of S/g-C3N4@β-Bi2O3 heterojunction and its photocatalytic degradation of toluene in the gas phase.

In this paper, a modification of g-C3N4 was carried out by combining non-metal doping with the construction of heterojunctions, and a type II heterojunction composite, S/g-C3N4@β-Bi2O3, was prepared. The phase structure, morphology, elemental composition, valence band structure, and light absorption performance of the photocatalyst were analyzed using characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The performance of the composite photocatalyst in the photocatalytic degradation of gaseous toluene, one of the typical volatile organic compounds (VOCs), under simulated solar light was studied. The effects of preparation conditions, toluene concentration, and recycling on the photocatalytic performance of the composite photocatalyst were investigated. The results show that under the optimal preparation conditions, S/g-C3N4@β-Bi2O3 achieved a degradation efficiency of 74.0% for 5ppm toluene after 5h of light irradiation. Although the degradation efficiency decreased to 61.2% after five cycles, it maintained 83% of its initial activity, indicating good stability of the composite photocatalyst. Free radical quenching experiments demonstrated that h+ was the main active species in the photocatalytic degradation of toluene, followed by ·O2-. Based on all experimental results, the migration law of photo-generated charges was analyzed, and a possible photocatalytic mechanism was proposed. In this study, a new material was obtained for the photocatalytic removal of VOCs by improving the photocatalytic properties of g-C3N4.

Ball-Milling Enhanced UV Protection Performance of Ca2Fe-Sulisobenzone Layered Double Hydroxide Organic Clay.

Using a co-precipitation technique, the anionic form of sulisobenzone (benzophenone-4) sunscreen ingredient was incorporated into the interlayer space of CaFe-hydrocalumite for the first time. Using detailed post-synthetic millings of the photoprotective nanocomposite obtained, we aimed to study the mechanochemical effects on complex, hybridized layered double hydroxides (LDHs). Various physicochemical properties of the ground and the intact LDHs were compared by powder X-ray diffractometry, N2 adsorption-desorption, UV-Vis diffuse reflectance, infrared and Raman spectroscopy, scanning electron microscopy and thermogravimetric measurements. The data showed significant structural and morphological deformations, surface and textural changes and multifarious thermal behavior. The most interesting development was the change in the optical properties of organic LDHs; the milling significantly improved the UV light blocking ability, especially around 320 nm. Spectroscopic results verified that this could be explained by a modification in interaction between the LDH layers and the sulisobenzone anions, through modulated π-π conjugation and light absorption of benzene rings. In addition to the vibrating mill often used in the laboratory, the photoprotection reinforcement can also be induced by the drum mill grinding system commonly applied in industry.

Tuning the local structure of (Sm, Co) Co-doped Al2O3 system for optical band gap and low dielectric loss

This study is about the qualitative description of the high dielectric constant (>103) and low dielectric loss in a two co-existing phases. According to earlier beliefs, a material with high dielectric constant will exhibit high dielectric loss. However, this study gives the opposite, where a material with high dielectric constant can exhibit low loss. Herein, we report on the effect of tetrahedral – octahedral interaction in a γ- Al2O3 and CoAl2O4 biphasic system. Phase identification was carried out using Synchrotron x-ray carrying a wavelength of 0.7 Å. The disorder caused by varying cobalt (Co) concentration results in a two co-existing phase system with varying local polarizability due to mixing of cations in a host matrix. In addition, a decreasing trend in the band gap energy has been observed for both the phases as a function of increasing Co concentration, which is attributed to the intra-gap localized density of states determined from the UV–Vis diffuse reflectance spectroscopy (DRS).

Determination of solid-state acidity of lyophilized trehalose containing citrate, phosphate, and histidine buffers using UV/VIS diffuse reflectance and solid-state NMR spectroscopy

Changes in the protonation state of lyophilized proteins can impact structural integrity, chemical stability, and propensity to aggregate upon reconstitution. When a buffer is chosen, the freezing/drying process may result in dramatic changes in the protonation state of the protein due to ionization shift of the buffer. In order to determine whether protonation shifts are occurring, ionizable probes can be added to the formulation. Optical probes (dyes) have shown dramatic ionization changes in lyophilized products, but it is unclear whether the pH indicator is uniform throughout the matrix and whether the change in the pH indicator actually mirrors drug ionization changes. In solid-state NMR (SSNMR) spectroscopy, the chemical shift of the carbonyl carbon in carboxylic acids is very sensitive to the ionization state of the acid. Therefore, SSNMR can be used to measure ionization changes in a lyophilized matrix by employing a small quantity of an isotopically-labeled carboxylic acid species in the formulation. This paper compares the apparent pH of six trehalose-containing lyophilized buffer systems using SSNMR and UV-Vis diffuse reflectance spectroscopy (UVDRS). Both SSNMR and UVDRS results using two different ionization probes (butyric acid and bromocresol purple, respectively) showed little change in apparent acidity compared to the pre-lyophilized solution in a sodium citrate buffer, but a greater change was observed in potassium phosphate, sodium phosphate, and histidine buffers. While the trends between the two methods were similar, there were differences in the numerical values of equivalent pH (pHeq) observed between the two methods. The potential causes contributing to the differences are discussed.

Visible-light-driven photocatalytic oxidation of furfural to furoic acid over Ag/g-C3N4

Furoic acid (FA) is a useful bio-chemicals, which can be used in the production of pharmaceuticals, food additives, flavors, industrial chemicals, biofuels, etc. Oxidation of furfural to FA has been carried out by a thermal catalytic method, but photocatalytic oxidation protocol has not been reported yet. Here, g-C3N4-supported Ag nanoparticles (Ag NPs) catalysts with different Ag loading were synthesized and used for the photocatalytic oxidation of furfural to FA under visible light irradiation. The physicochemical and photoelectrochemical properties of the catalysts were systematically investigated by XRD, TEM, XPS, UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS), photoluminescence, etc. Compared with the pristine g-C3N4, Ag-CN(N2 + H2) was found to have better photocatalytic performances in the aerobic oxidation of furfural under visible light irradiation, and the conversion can reach 82 % with a FA yield of 30 %. Importantly, the loading of Ag NPs has a significant effect on the photoelectrochemical properties. Specifically, 0.5 % Ag NPs loading maximized the photocurrent response, indicating that the loading of Ag NPs enhances charge separation and migration under visible light excitation. The introduction of Ag NPs also led to a significant decrease in electrochemical impedance, which promoted the rate of electron transfer at the interface, further confirming the improved photocatalytic efficiency. The addition of Ag NPs broadens the solar absorption and promotes the separation/transport of photo-generated carriers to form “hot electrons”, and provides the active species for furfural oxidation. The reasonable reaction mechanism of the photocatalytic oxidation of furfural to FA was elucidated. This work offers a novel method for the oxidation of furfural to FA in a mild and green way.