Ultraviolet-visible Diffuse Reflectance Spectroscopy Research Articles

Investigating the impact of sodium (Na) dopant on the structural, morphological, optical, and magnetic properties of LaPrSrMnO3 perovskite nanoflakes

Abstract Here we report the structural, optical and magnetic properties of La0.4Pr0.25Na x Sr0.35−x MnO3 (x = 0, 0.05, and 0.1) synthesized using ball milling method. After milling, the precursors are calcinated at 1,200 °C for 12 h. The phase purity, crystal structure, lattice parameter, and crystallite size of the samples were determined using X‐ray diffraction (XRD). The peaks from XRD provide the perovskite hexagonal structure with an R 3 ‾ $\overline{3}$ c space group. Surface morphology shows the recreation of spherical structure to nanoflakes/layered structures. The ultraviolet-visible diffused reflectance spectroscopy (UV–vis DRS) study indicates that the decrease in the band gap is observed with the increase of Na content. The intensity of the luminescence peak decreases progressively with the increase of Na doping. The room temperature (RT) magnetization of the samples reveals weak ferromagnetism and shows a novel vertical shift in magnetization at room temperature.

Photocatalytic degradation of methylene blue by efficient TiO2‐partially reduced graphene oxide composites

The effect of graphene oxide with different reduction degrees on the photocatalytic efficiency of titanium dioxide‐graphene (TiO2‐G) composites has not been systematically studied. In this paper, titanium dioxide‐partially reduced graphene oxide (TiO2‐PRGO) nanocomposites were prepared by a modified one‐step solvent‐thermal method and further reduced with ascorbic acid to obtain TiO2‐PRGO(xh) with a higher degree of reduction (ascorbic acid 80° reduced TiO2‐PRGO x h, x = 1, 2, 3, 4). The composites were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT‐IR), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and ultraviolet–visible diffuse reflectance spectroscopy (DRS). The transient photocurrent response and electrochemical impedance results show that TiO2‐PRGO has the most outstanding photoelectrochemical properties. Compared with pure TiO2 and other samples, the TiO2‐PRGO nanocomposites exhibited excellent photocatalytic properties, and their photocatalytic efficiencies for the degradation of methylene blue (MB) were up to seven times higher than those of the pure TiO2 nanomaterials, and twice that of TiO2‐PRGO(4h). The photodegradation of methylene blue by the composites decreased as the degree of PRGO reduction increased. The efficient photocatalytic performance of TiO2‐PRGO can be attributed to the high TiO2 loading and good electrical conductivity. Notably, TiO2‐PRGO photocatalysis for 90 min resulted in 100% degradation of MB. Meanwhile, TiO2‐PRGO has good reusability, and the degradation rate of TiO2‐PRGO remained at 95% after four times of degradation in MB solution.

Thermotropic Structure Phase Transitions and Two Types of Thermochromic Behaviors in a Bromoargentate Cluster [Pr-dabco]2Ag4Br6.

Organic-inorganic silver halide hybrids show abundant phase transitions and thermochromism. However, it is very rare that silver halides exhibit thermochromism related to thermotropic structure phase transition. Herein, a bromoargentate hybrid, [Pr-dabco]2Ag4Br6 (1) (Pr-dabco+ = 1-propyl-1,4-diazabicyclo-[2.2.2]octan-1-ium), with tetranuclear [Ag4Br6]2- clusters was prepared and characterized by microanalysis, ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy, and thermogravimetric (TG) and differential scanning calorimetry (DSC) techniques. Interestingly, 1 undergoes an irreversible structure phase transition at ∼436 K in the first heating process, which is accompanied by an abrupt color change from colorless to yellow; however, a reversible color change between pale yellow and yellow is observed in the next heating-cooling cycles. Notably, DSC measurement revealed that a reversible phase transition is associated with the change in color between pale yellow and yellow, while the powder X-ray diffraction (PXRD) patterns corresponding to pale yellow and yellow phases are quite similar to each other. These observations demonstrate that thermochromism in the next heating-cooling runs is associated with a reversible structure phase transition, which perhaps concerns the disorder-order transformation of alkyl chains in the cationic ligand [Pr-dabco]+, and relevant to the anharmonic fluctuations of the Ag-Br and Ag-N bonds, a strong electron-phonon coupling effect is seen within the bromoargentate cluster.

Green synthesis of CuO/Fe2O3/ZnO ternary composite photocatalyst using grape extract for enhanced photodegradation of environmental organic pollutant

This research delves into fabricating a CuO/Fe2O3/ZnO (CFZ) ternary composite photocatalyst, employing grape extract for its eco-conscious synthesis. The method intricately integrates copper acetate, ferric nitrate, and zinc acetate as precursor compounds, harmonizing them with grape extract serving as a green reducing agent. Meticulous microwave treatment and controlled calcination orchestrate the nuanced formation of the desired composite material. The extensive characterization, involving X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDXS), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, ultraviolet–visible diffuse reflectance spectroscopy (UV-DRS), and photoluminescence (PL) spectroscopy, unveils an array of favorable physical, chemical, and optical attributes conducive to proficient photocatalysis. Notably, CFZ–10mc showcases a narrower bandgap of 1.91 eV, which is pivotal for bolstering electron–hole separation, thereby enhancing its photocatalytic efficacy. Assessment of CFZ's performance in degrading Rhodamine B (RhB) under UV irradiation highlights an impressive 88.8% degradation efficiency within 120 min, accompanied by a kinetic rate constant of 1.81 × 10−2 min−1. Deliberation upon crucial parameters, including photocatalyst dosage, initial RhB pH, and reactor energy consumption, introduces the electrical energy per order (EEO) as a notable efficiency metric. CFZ manifests a substantial reduction in operational costs, estimated to be 18.10 times lower than conventional photolysis, signifying an EEO value of 509.17 kWh m−3 order−1. Optimal operational conditions propose a photocatalyst content of 1.5 g L−1 and an initial RhB pH of 7, fostering the prevalence of the primary active species, •OH. These findings illuminate CFZ's potential in mitigating organic pollutants, underlining its pivotal role in sustainable water remediation. Additionally, practical implementation guidelines for leveraging CFZ's capabilities in real-world applications are presented with care and consideration.

Fe3O4-CdO Nanocomposite for Organic Dye Photocatalytic Degradation: Synthesis and Characterization

In this study, pure CdO nanoparticles, magnetic Fe3O4 nanoparticles, and Fe3O4-CdO nanocomposites were prepared via a solution combustion method using cetyltrimethylammonium bromide (CTAB) as a template. These prepared nanomaterial samples were characterized by X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron microscopy (XPS), transmittance electron microscopy (TEM), and scanning electron microscopy (SEM) analysis. XRD patterns confirmed the purity and the crystalline nature of the prepared samples. FTIR and Raman spectra observed the metal-oxygen (M-O) bond formation. UV-vis DRS studies were performed to investigate the optical properties and the bandgap energy determination. The surface morphology and the size of the pure CdO nanoparticles, magnetic Fe3O4, and nanocomposites of Fe3O4-CdO were determined via TEM and SEM analysis. Under optimum experimental conditions, the Fe3O4-CdO nanocomposites were applied for photocatalytic activity against Methylene blue dye. Under visible light irradiation, Fe3O4-CdO nanostructures showed an efficient photocatalytic degradation of 92% against Methylene blue organic dye and showed excellent stability for multiple cycles of reuse.

Ultra-deep photocatalytic oxidative desulfurization of liquid fuels by Ti@CeO2/ZnO nanophotocatalyst under visible light and mild operating conditions

Herein, various Ti@CeO2/ZnO nanophotocatalysts (TxCZ, x: the molar ratio of Ti to Ce and Zn) were synthesized using the solvothermal method in two stages. After that, the effectiveness of the fabricated catalysts in the photocatalytic oxidative desulfurization (PODS) reaction were assessed. The physicochemical properties of the synthesized samples were analyzed through the implementation of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), photoluminescence spectroscopy (PL), and electron paramagnetic resonance (EPR) techniques. The study evaluated the impact of varying levels of titanium loading on the physicochemical characteristics of nanoparticles and the elimination of sulfur compounds. Under the optimal reaction conditions of T = 50 °C, 1.5 g/L of photocatalyst dosage, an oxidant to sulfur molar ratio of 6, and a solvent to fuel volume ratio of 1, the TxCZ sample exhibited superior performance by completely removing dibenzothiophene (DBT) from the model fuel. Kinetic studies indicate that the PODS reaction adheres to the pseudo-first-order kinetic model, with an observed activation energy of 69.25 kJ/mol−1.

Exploration of properties (crystallographic, morphological, optical) of nano cobalt aluminate synthesized by facile sol–gel method: Effects of sintering temperature

The present work reports on the facile sol–gel synthesis of CoAl2O4 nanoparticles using cobalt nitrate and aluminum nitrate as the metal salts and citric acid and glycerol as chelating agents. The consequence of sintering temperature on the structure, particle size, morphology, composition, zeta potential, color, and reflectance spectra at neutral pH condition were explored with various instrumental techniques. The CoAl2O4 nanoparticles were characterized with Powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FESEM), Energy dispersive spectroscopy (EDS), Nanoparticle size analyzer, Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV–Vis-DRS) and CIE-Lab colorimetric method. From the data of PXRD, the crystallite size and peak profile analysis were investigated by four different models. It was found that the average crystallite size varied in the range of 28.01–320.97 nm and single-phase cubic CoAl2O4 was formed without any impurity. The average particle size of CoAl2O4 nanoparticles was discerned from the FESEM images using ImageJ software and from a nanoparticle size analyzer. The average particle sizes were increased with the increasing sintering temperature. The values of zeta potential found in all of the samples represented high dispersion stability. From the colorimetry of CoAl2O4 nanoparticles, the CIE-La*b* output illustrated high purity and brightness and the spectra.

Tailoring structural, optical, and magnetic properties of Y3+ doped CoFe2O4 nanoparticles to enhance photocatalytic activity

In recent times, there has been a significant focus on semiconductive magnetic nanomaterials due to their potential in photocatalytic applications, primarily because of their easy recoverability. In this work, CoYxFe2-xO4 nanoparticles (with varying x values: 0, 0.05, 0.10, 0.15, and 0.20) were successfully synthesized. The incorporation of Y3+ ions induced notable transformations in the structural, optical, microstructural, magnetic, and photocatalytic properties of CoFe2O4 nanoparticles. Analytical techniques such as x-ray diffraction, fourier transform infrared spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, photoluminescence, transmission electron microscopy, vibrating sample magnetometry, and electron paramagnetic resonance spectroscopy were employed to investigate these effects. The investigation into the photocatalytic degradation of methylene blue (MB) under ultraviolet light irradiation was carried out. The influence of distinct elemental compositions, catalyst quantities, irradiation durations, and initial methylene blue concentrations on the decolorization process was assessed.

IMPROVED ACIDITY OF MESOPOROUS ZrO2-WO3 THROUGH NH3-AIR SUBSECTION-CALCINATION TREATMENT

ZrO2-WO3 mixed metal oxides are important solid acid catalysts, and typically, ammonia gas calcination reduces their acidity. However, in this study, we introduce an updated NH3 calcination technique that can increase the acidity of mesoporous ZrO2-WO3 solid acids. Their structures and acid properties were thoroughly characterized through X-ray diffraction (XRD), N2 adsorption measurement, pyridine-adsorbed infrared spectroscopy (Py-IR), temperature-programmed desorption of ammonia (NH3-TPD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis-DRS) analysis. The resulting materials exhibit remarkable activity in the Friedel-Crafts (F-C) reaction of anisole and benzyl alcohol. Our investigations showed that the subnanometer WOx clusters act as the most active sites for the F-C reaction, and NH3-air calcination is essential for the formation of WOx clusters. This treatment not only enhances acidity but also provides a novel method of obtaining acidic ZrO2-WO3 mixed metal oxides. Most importantly, it presents a fresh approach for regulating the formation of WO3 clusters and catalytic activity.

La-doped MIL-88B(Fe)-NH2: a mixed-metal-organic framework photocatalyst for highly efficient reduction of Cr(vi) in an aqueous solution.

With the aim to resolve the problem of water pollution, we herein propose a new photocatalyst based on metal-organic frameworks (MOFs), called La-doped MIL-88B(Fe)-NH2 (MIL-88B((1 - x)Fe/xLa)-NH2), which was designed and employed for the photocatalytic reduction of Cr(vi) in aqueous solutions. MIL-88B((1-x)Fe/xLa)-NH2 materials with different x values were synthesized via a one-pot solvothermal method. Their characteristics were investigated using various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Brunauer-Emmett-Teller (BET) analysis, Fourier-transform infrared (FT-IR) spectroscopy and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). We found that compared to pristine MIL-88B(Fe)-NH2 with a photocatalytic efficiency of 67.08, MIL-88B((1 - x)Fe/xLa)-NH2 materials with x = 0.010, 0.025 and 0.050 exhibit excellent photocatalytic efficiencies reaching 88.21, 81.19 and 80.26%, respectively, after only 30 minutes of irradiation at a small catalyst dosage of 0.2 g L-1. These La-doped MIL-88B(Fe)-NH2 photocatalysts can work well under mild conditions (pH = 6). Furthermore, they are robust-can be recycled for at least four consecutive runs without any activity loss. This novel material is promising for the photocatalytic degradation of pollutants.

Visible light driven degradation of BPA and LDPE microplastic films using GO/SCN nanocomposite.

A sonication assisted method was employed to prepare a graphene oxide (GO)/sulfur doped carbon nitride (SCN) nanocomposite, demonstrating enhanced photocatalytic activity compared to GO and SCN. Extensive characterization confirmed the improved properties of the nanocomposite. X-ray Diffraction (XRD) results indicated that the SCN lattice remained intact upon GO addition while Fourier-transform infrared spectroscopy (FTIR) revealed chemical interaction between GO and SCN. X-ray photoelectron spectroscopy (XPS) confirmed sulfur incorporation into the graphitic carbon nitride (g-C3N4) lattice. Scanning electron microscopy (SEM) and Transmission Electron Microscopy (TEM) highlighted the distinct morphological features of GO, SCN, and GO/SCN nanocomposites, with SCN showing flat, thin nanosheets and GO displaying flake-like layers, both contributing to a high surface area and mechanical strength. In the GO/SCN nanocomposite, these structures were intermixed, enhancing surface area, mechanical stability, and electron mobility, which contributed to the improved catalytic performance. Ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS) showed a reduction in band gap energy from 2.62 eV for SCN to 2.52 eV for the GO/SCN composite, leading to enhanced visible light absorption. Under visible light irradiation, low density polyethene (LDPE) films experienced significant degradation, evidenced by a 21% weight loss after 10 days, supported by SEM analyses showcasing surface changes on the LDPE films. The degradation was further confirmed by an increase in the carbonyl index (C.I.) from 0.37 to 1.24, measured through FTIR analyses, indicating oxidation corroborating the degradation process. Furthermore, BPA degradation reached 89.5% within 60 minutes under visible light irradiation. Radical trapping experiments confirmed hydroxyl radicals (˙OH) as the active oxygen species involved in the degradation of BPA.

Vaporization phosphorization-mediated synthesis of phosphorus-doped TiO2 nanocomposites for combined photodynamic and photothermal therapy of renal cell carcinoma.

Clear cell renal cell carcinoma (ccRCC) is a disease with high incidence and poor prognosis. The conventional treatment involves radiotherapy and chemotherapy, but chemotherapeutic agents are often associated with side effects, i.e., cytotoxicity to nontumor cells. Therefore, there is an urgent need for the development of novel therapeutic strategies for ccRCC. We synthesized spherical P/TiO2 nanoparticles (P/TiO2 NPs) by vaporization phosphorization (VP). X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS) analyses confirmed that the anatase TiO2 surface was successfully doped with phosphorus and produced a large number of oxygen vacancies (OV). Serving as a photosensitizer, P/TiO2 NPs not only extended the photoresponse range to the near-infrared II region (NIR II) but also introduced a donor energy level lower than the TiO2 conduction band, narrowing the band gap, which could facilitate the migration of photogenerated charges and trigger the synergistic treatment of photodynamic therapy (PDT) and photothermal therapy (PTT). During NIR irradiation in vitro, the P/TiO2 NPs generated local heat and various oxygen radicals, including 1O2, ˙O2-, H2O2, and ˙OH, which damaged the ccRCC cells. In vivo, administration of the P/TiO2 NPs + NIR reduced the tumor volume by 80%, and had the potential to inhibit tumor metastasis by suppressing intratumor neoangiogenesis. The P/TiO2 NPs showed superior safety and efficacy relative to the conventional chemotherapeutic agent used in ccRCC treatment. This study introduced an innovative paradigm for renal cancer treatment, highlighting the potential of P/TiO2 NPs as safe and effective nanomaterials and presenting a compelling new option for clinical applications in anticancer therapy.

Innovative ternary bismuth oxychloride/bismuth oxide/carbon nanotubes induced excellent solar light-driven activity toward photomineralisation of diclofenac: Impact of metastable β-Bi2O3 inserted and electron-hole separation

Solar energy-utilizing photocatalysts for water purification remain essential for environmental sustainability. This report presents new concepts in bismuth oxychloride/oxide/carbon nanotubes. (BiOCl/Bi2O3/CNT) composites, synthesized through a chemical deposition method involving BiOCl in a carbon nanotube bath, followed by surface reduction/oxidation steps. The impact of nanotube ratio and calcination temperature were explored. Characterization involved ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS), X-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), elemental mapping, N2 adsorption/desorption analysis, and electrochemical impedance spectroscopy (EIS). XRD analysis revealed in-situ formation of α and β-Bi2O3 phases, rendering the composite more responsive to visible light at 200 °C. Carbon nanotubes reduced the band gap of ternary composites, yielding lower band gap energies in the visible range compared to BiOCl and Bi2O3. XPS analysis identified metallic Bi0 particles, enhancing electron mobility and charge separation. The synergy of BiOCl/Bi2O3/CNT-200 material significantly improved diclofenac degradation under solar simulator irradiation. Total organic carbon (TOC) analysis demonstrated 81 % mineralization with the BiOCl/Bi2O3/CNT-200 material. Active species trapping revealed the crucial roles of HO• radicals and h+ holes in pollutant degradation. The presence of the normally metastable β-Bi2O3 phase at 200 °C enhanced solar simulation efficiency, while carbon nanotubes acted as electron reservoirs, aided by Bi0 particles. The present study sets out an efficient composite synthesis approach for the photomineralization of complex pharmaceutical compounds.

Preparation and enhanced photocatalytic performance of N-TiO2/g-C3N4 heterostructure for Rhodamine B degradation

Highly efficient photocatalysts have been developed for the degradation of contaminated water under visible light. In this study, N-doped TiO2 (N-TiO2) and metal-free graphitic carbon nitride (g-C3N4) composites with various Ti/C molar ratios were prepared with the simple mixing-calcining method. The samples were characterized by X-ray diffraction, scanning electron microscopy, ultraviolet–visible diffuse reflectance spectroscopy, and photoluminescence spectroscopy. The photocatalytic activity of N-TiO2/g-C3N4 in the degradation of Rhodamine B (RhB) was investigated, and the electrochemical method was used to determine the origin of the enhanced photoactivity of N-TiO2/g-C3N4. The results showed that N-TiO2 nanoparticles were dispersed on the surface of g-C3N4 and formed a stable heterojunction structure with g-C3N4. The heterojunction between the two semiconductors could effectively prevent the recombination of photogenerated electrons and holes and improve the photocatalytic efficiency of the photocatalyst under visible light irradiation. The photocatalyst exhibited high stability, and the RhB degradation rate was still higher than 82.3% after five cycles.

Photocatalytic degradation of SBX in mineral processing wastewater with hollow CdS/MWCNTs nanocomposites

In this study, a novel hollow sphere CdS/MWCNTs composite photocatalytic material was prepared by hydrothermal method and was first used for the photocatalytic degradation of sodium butyl xanthate (SBX) in sulfide mineral processing wastewater. The morphology structure and photocatalytic properties of hollow sphere CdS/MWCNTs composite catalyst were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectroscopy (UV–vis DRS), thermogravimetric analysis (TGA) and photocatalytic activity experiments. The results showed that 15 mg CdS/MWCNTs with the 5 % MWCNTs doping amount possessed the highest photocatalytic degradation efficiency for SBX which the degradation rate reach 99 %. The hollow sphere structure and addition of MWCNTs obviously improved the migration and separation of photogenerated electrons (e−) and holes (h+) of pure CdS, leading to high photocatalytic efficiency.

Rational design and fabrication of novel MnSeO3/GO nanocomposites for catalysis applications: Analysis of degradation efficacy, stability and degradation pathway

The MnSeO3/GO nanocomposites were effectively synthesized using a hydrothermal technique. The structural analyses of the heterogeneous catalyst were validated through the utilization of diverse characterization techniques, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet–visible diffuse reflectance spectroscopy (UV-DRS), and energy-dispersive X-ray spectroscopy (EDX) investigations. The surface of graphene oxide (GO) exhibits well-aggregated MnSeO3 particles, as shown by the utilization of analytical techniques such as FT-IR,EDX, and SEM. The structural characteristic of the sample demonstrated a satisfactory synthesis process, resulting in well-formed crystals and high purity of the final products. The results of the morphological study suggest that MnSeO3nanorods are formed, characterized by the presence of small particles on their surface. Simultaneously, the formation of GO nanosheets exhibiting pronounced aggregation occurred, potentially attributed to the influence of van der Waals forces. The optical properties of different samples were determined and the values are 2.06 eV for MnSeO3 and 1.81 eV for MnSeO3/GO. The photodegradation process of antibiotic drug Cefuroxime (CEF) and pesticide Methyl parathion (MP) was investigated using UV–visible spectroscopy, with the involvement of MnSeO3/GO nanocomposites. The results demonstrate a photocatalytic activity over 90 % during a time frame of 50 and 60 min under visible light exposure for CEF and MP degradation. In the field of scavenger research, the hydroxide radical assumes a prominent role in the mechanism of photodegradation. In addition, the stability of the photocatalyst were determined by recycle analysis. The analysis of the intermediates resulting from photocatalytic degradation was conducted by GC–MS investigations.

Synthesis of ZnO/NiO/g-C3N4 Nanocomposite Materials for Photocatalytic Degradation of Tetracycline Antibiotic

In this study, an approach was utilized to improve the photocatalytic efficacy of g-C3N4 by creating a composite photocatalyst through co-precipitation. This process involved incorporating NiO and ZnO into the structure, resulting in enhanced photocatalytic activity. The Scanning Electron Microscopy (SEM) showcases interesting aggregation behavior, revealing extensive arrays of ZnO/NiO/g-C3N4 particles. Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV-Vis DRS) confirms the composite's strong light absorption, especially in the visible spectrum. X-ray diffraction (XRD) analysis provides conclusive evidence of successful material synthesis. The degradation of tetracycline antibiotics under visible light exposure demonstrates an impressive photochemical degradation efficiency of 78.43%. Additionally, the composite exhibits impressive cycles of reuse, retaining its high photocatalytic activity even after four reaction cycles. This performance surpasses that of comparison samples. The synergistic integration of NiO and g-C3N4 within ZnO proves to be crucial in enhancing photocatalytic activity by enhancing electron-hole separation and mitigating recombination processes. This composite photocatalyst shows a wide potential for efficiently eliminating tetracycline antibiotics from water systems. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Photocatalytic oxidative desulfurization of model fuel using iron-molybdenum nanocatalyst based on cerium oxide (FeyMox/CeO2) under visible light

Iron and molybdenum-activated CeO2 nanoparticles were utilized in a photocatalytic oxidation reaction in order to eliminate sulfur compounds from a model fuel. The catalyst was synthesized through a two-step process and then calcined for 3 h at 600 °C. The physicochemical properties of the synthesized nanophotocatalyst were characterized using a range of techniques, including X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS), photoluminescence spectroscopy (PL), nitrogen adsorption–desorption, and thermogravimetric analysis (TGA). The sample of Fe1Mo2/CeO2 exhibited superior performance in the photocatalytic oxidative desulfurization (PODS) reaction. The PODS reaction parameters, such as the initial sulfur concentration, photocatalyst dosage, temperature, solvent-to-fuel volume ratio (S/F), and oxidant-to-sulfur molar ratio (O/S), underwent optimization. Under ideal circumstances (T = 50 ℃, photocatalyst dosage = 2 g/L, O/S = 6, and S/F = 1), a 100% conversion rate of DBT was achieved. The kinetic studies showed that the PODS reaction follows the pseudo-first order kinetic model, and the activation energy measured was 39.44 kJ/mol−1.

Physical Properties of ZnO-NPs Induced by the Thermal Annealing of Hydrozincite Derived from Adansonia Digitata Leaves Extract

In this study, we investigated the effects of the annealing temperatures on the physical properties of zinc oxide nanoparticles produced by the decomposition of the hydrozincite obtained from Adansonia digitata leaves. The results of the X-ray diffraction revealed the formation of well-crystallised hexagonal zinc oxide with an average crystallite size of 11.80 nm, 11.90 nm, 11.97 nm and 15.28 nm for the samples annealed at 400 °C, 500 °C, 600 °C and 700 °C, respectively. The crystallite size of the hydrozincite constituting the unannealed sample was 22 nm. In the spectra of the Fourier transform infrared spectroscopy, the appearance of the peaks at 520 cm-1 for all synthesised materials confirms the formation of pure wurtzite zinc oxide. The band gap determined from diffuse reflectance ultraviolet-visible spectroscopy was found to be 3.19 eV, 3.21 eV, 3.23 eV and 3.24 eV for the samples annealed at 400 °C, 500 °C, 600 °C and 700 °C, respectively. These values increase with the annealing temperature and are still lower than the band gap of pure bulk zinc oxide (3.3 eV) owing to the structural defects as confirmed by the broad emission bands in the visible depicted from the photoluminescence analysis.

Effect of multi-walled carbon nanotubes on the visible light photocatalytic activity of AgInS2 for Rhodamine B degradation

Visible-light responsive AgInS2 (AIS) nanoparticles modified with either pristine multi-walled carbon nanotubes (p-MWCNTs) or mixed-acid (H2SO4 and HNO3) oxidized multi-walled carbon nanotubes (o-MWCNTs) were synthesized using a low-temperature liquid phase method. The resulting nanocomposites are denoted as p-MWCNTs/AIS or o-MWCNTs/AIS. The structure, morphology, and optical properties of the samples were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), photoluminescence spectroscopy (PL), and ultraviolet-visible diffuse reflectance spectroscopy (UV–Vis DRS). The photocatalytic activity of p/o-MWCNTs/AIS towards the degradation of Rhodamine B (RhB) was investigated, and the optimal proportion of p/o-MWCNTs introduced on AIS was determined. A possible degradation mechanism of RhB over p/o-MWCNTs/AIS was proposed. The results demonstrated that p/o-MWCNTs were successfully incorporated into AIS, and the addition of an appropriate amount of p/o-MWCNTs improved the visible-light photocatalytic activity of AIS. Among the samples, 2 % o-MWCNTs/AIS exhibited the highest visible-light catalytic activity, achieving a degradation efficiency of 95 % within 40 min. The·⋅O2− species were identified as the main active species during the photocatalytic degradation process. The introduction of o-MWCNTs not only facilitated the separation of photogenerated electron-hole pairs (e−/h+) in AIS but also enhanced the visible-light absorption of AIS, leading to a significant improvement in its photocatalytic performance. Furthermore, the incorporation of o-MWCNTs greatly enhanced the cycling stability of AIS for reuse.