Photoluminescence Techniques Research Articles

A Deeper Investigation of New Organic Nanocomposite System MEH‐PPV‐P3HT/SWCNT for Optoelectronic Applications

ABSTRACTThis work aims to experimentally investigate the elaborated nanocomposite based on the MEH‐PPV‐P3HT copolymer as a donor, which blended with the SWCNTs as an acceptor with different weight concentrations (1%, 3%, and 5% of SWCNTs). Various characterization techniques have been performed to analyze the effect of varying the SWCNTs' weight and the interaction between the two materials. The morphological and vibrational analysis were carried out using transmission electron microscopy (TEM) and Raman's spectroscopy, which indicate the dispersion of the SWCNT in the copolymer matrix. To analyze the optical properties, UV–visible, photoluminescence, and time‐resolved photoluminescence techniques have been used. To ascertain the influence of the SWCNTs addition, a comparative study between the resulting nanocomposite, basic copolymer, and various SWCNT concentrations has been examined. The results that have been accomplished demonstrate that the mixing between the copolymer MEH‐PPV‐P3HT and the SWCNTs reduces the band gap energy to be equal to 1.7 eV enhancing the charge transfer (CT) process and increases the absorption volume in the visible range. An increment in the average decay time compared to the MEH‐PPV‐P3HT has been noticed which improves the non‐radiative luminescence process. To analyze the intermolecular interaction, theoretical modeling using density functional theory (DFT) has been performed.

Quasi-point NIR light source based on laser-driven photoluminescence for eye-safe imaging applications

Near-infrared (NIR) imaging, as a newly emerged technique, demonstrates immense potential in various imaging applications such as biological detection, night vision, and anti-counterfeiting. The imaging quality of the currently available NIR light sources is limited by their low radiant exitance and poor beam quality. Herein, a quasi-point NIR light source based on a laser-driven photoluminescence technique was successfully developed. A single blue laser diode (LD) with a power of ∼2250 mW and a minimum spot size of ≈ 0.13 mm-2 is employed as the pumping source. A Cr-doped MgO ceramic displaying strong luminescence in the NIR region is used as the emitter. Interestingly, the prepared MgO:Cr ceramic is able to withstand the blue laser irradiation density of > 5600 mW·mm-2, and therefore, the fabricated NIR light source demonstrates a high radiant flux of ∼234 mW with a high radiant exitance of ∼139 mW·mm-2. Furthermore, the emitting area is as small as ∼1.6 mm2, which is highly beneficial for optical design and device miniaturization. The overall performance of the quasi-point NIR light source in blood vessel imaging and night vision applications is evaluated.

The effect of Ce3+ ions on the optical, and radiation shielding properties in Ba–Sn borophosphate glass

This study aims to investigate the structural, optical, and mechanical properties of Ce3+ doped Barium Tin Borophosphate glass for potential applications in nuclear radiation shielding. The Ce3+ Doped Barium Tin Borophosphate glass (50B2O3+20 P2O5+10TiO2+6SrCO3+4SnO+ 4BaF2+5BaCO3+1Ce2O3) was produced according to earlier research, melt quenching method. The amorphous nature of Ce3+ Doped Barium Tin Borophosphate glass was verified by powder X-ray diffraction investigation. The Ce3+ Doped Barium Tin Borophosphate glass's functional groups were determined using Fourier transform-RAMAN and Fourier transform infrared spectroscopy. Using Ultraviolet-Visible spectroscopy the Ce3+ Doped Barium Tin Borophosphate glass was examined. These properties included its optical band gap, extinction coefficient, optical conductivity, and refractive index. Using EDAX and SEM analyses, the chemical compositions and surface morphology of the Ce3+ Doped Barium Tin Borophosphate glass were examined. Ce3+ doped barium tin Borophosphate glass was studied in terms of its excitation and emission spectra using the photoluminescence technique. The glass's CIE coordinates were also looked at. Additionally, the mass attenuation coefficient, half-value layer, mean free path, tenth value layer, and EABF were studied concerning the glass's gamma-ray shielding qualities using the Phy-X software.

The role of BaTiO3 nanoparticles as photocatalysts in the synthesis and characterization of novel fruit dyes is investigated.

In the present work, the photocatalytic activity against the natural dye extracted from the novel fruits has been studied by the BaTiO3 nanoparticles (NPs) under a ultra-violet (UV) light source. The large concentrations of an essential phenolic agent present in this phytochemical extract superimposed with cloths fibers make strong stain and degrade into another form of toxic, which is excluded from the many textiles industries as the colorful waste waters without recycling and removal of that dye pigments have been investigated using both photodegradation and photoluminescence techniques. The entitled nanoparticles (NPs) were prepared using the soft chemical root-modified solvothermal synthesis combo method and exposure to heat treatment such that the annealing process has been done for different temperatures ranging from 100°C to 250°C. As for as concern the characterization, as a start, structural and morphology studies have been reported here that highly crystalline oriented peaks data using powder x-ray diffraction techniques (PXRD) as well as the surface morphology including the size, shape, and mass distribution using the field emission scanning electron microscopy (FESEM) techniques, which purely belong to rutile tetragonal structure of the crystal system and circular and noncircular flakes like rough surface morphology materials respectively. The lattice dissociation constant 'ε' value of the BaTiO3 NPs has determined to be ~2.71 × 10-3 using the Williamson-Hall (W-H plot) analysis of crystallographic data. In the UV visible spectroscopy findings, since the extreme quantum confinement of BaTiO3 nanoflakes/nanodisc, the optical energy bandgap has been estimated to be a range of 1.98 to 2.67 eV (~2.48 eV) found from the Tauc plot analysis, which contributes to the significantly owing to the enhanced photocatalytic efficiency with excellent performance along exciton formation, superoxide ions, and hydroxyl free radicals generations under UV-vis light irradiation resulting in efficient degradation of typical novel fruit organic dye. Photoluminescence spectra observed at room temperature and low temperature have been observed for the BaTiO3 nanoflakes, which exhibit the blue emission due to the crystalline defects such as the appearance of Ba vacancies leads to the conceivable beginning of p-type conductivity and the origination of free exciton emission reveals the direct bandgap transition nature of nanoflakes. RESEARCH HIGHLIGHTS: According to our findings, 89.71% of the natural syzygium cumin is degraded by photocatalysis reaction. As a plausible mechanism for the destruction of natural dyes under solar light, photocatalytic destruction has been proposed. The reaction between these reactive free radical species leads to high efficiency photodegradation with a short decay time. In addition to water treatment and environmental cleaning applications, the excellent performance of this photocatalyst makes it a promising candidate for other applications. Hence, the synthesized BaTiO3 nanoflakes showcase a highly significant advancement towards the development of a textiles dye recycling method.

Scanning Acousto-Optoelectric Spectroscopy on a Transition Metal Dichalcogenide Monolayer.

The charge carrier dynamics are investigated by surface acoustic waves (SAWs) inside a WSe2 monolayer on LiNbO3 by scanning acousto-optoelectric spectroscopy. A strong enhancement of the PL emission intensity is observed almost over the entire area of the flake. This enhancement increases with increasing amplitude of the wave and is especially strong at or in the vicinity to defects. The latter is attributed to the SAW-driven Poole-Frenkel activation of trapped charge carriers bound to trapping sites at these defects. In addition, the PL intensity exhibit clear periodic modulations at the SAW's frequencyfSAW and at 2 fSAW. These modulations are clear and unambiguous fingerprints of spatio-temporal carrier dynamics driven by the SAW. These occur on sub-nanosecond timescales which are found in good agreement with calculated exciton dissociation times. Mapping and analyzing both effects, this study shows that scanning acousto-electric spectroscopy provides a highly sensitive and local contact-free probe which uncovers distinct local features not resolved by conventional quasi-static photoluminescence techniques. The method is ideally suited to study carrier transport in 2D and other types of nanoscale materials and to reveal dynamic exciton modulation, and carrier localization and activation dynamics in the technologically important megahertz to gigahertz frequency range.

Pressure-Induced Structural Phase Transitions and Photoluminescence Properties of Micro/Nanocrystals HoF3.

HoF3 crystals of varying sizes and morphologies were synthesized by controlling the amount of water. As the water content gradually decreased, the size of the crystals reduced, transforming from microcrystals to approximately 100 nm nanocrystals with unique morphologies. At room temperature, the pressure-induced phase transitions, and photoluminescence (PL) properties of HoF3 micro/nanocrystals are studied using in situ high-pressure PL technique. The PL spectra show that the HoF3 micro/nanocrystals exhibit two structural phase transformations at 5 (6 GPa for NCs) and 12 GPa. Nanoparticles have higher fluorescence intensity, which initially increases and then decreases with changes in pressure. Based on first-principles calculations, HoF3 transforms from an orthorhombic structure to a hexagonal structure during the phase transition, with the coordination number of holmium atoms increasing from 9 to 11. The high-pressure Raman spectra on lattice modes also confirmed the existence of the two phase transitions. This work not only provides precise structural changes but also facilitates the understanding of two typical structures of rare-earth trifluoride (REF3), which may play an important role in the application of the RE family.

Zinc oxide-based sensor prepared by modified sol–gel route for detection of low concentrations of ethanol, methanol, acetone, and formaldehyde

Abstract We4 4 We received the acceptance date as 26 September 2024. Could you please update it to reflect this exact date for our project, instead of 1 October 2024? This is very important for our project funding. successfully synthesized zinc oxide (ZnO) nanoparticles using the sol–gel method, followed by their application onto alumina substrates for sensor testing. Comprehensive characterization of the nanomaterials was carried out utilizing XRD, SEM, TEM, UV–VIS-IR, and Photoluminescence (PL) techniques. The nanoparticles displayed a hexagonal wurtzite crystal structure, typical of ZnO. UV–Vis-IR spectroscopy revealed significant absorption in the UV region, with the band gap energy calculated to be 3.22 eV. PL spectra indicated the presence of various defects, such as oxygen vacancies and zinc interstitials, within the ZnO structure. SEM analysis of the deposited film surface showed spherical agglomerates, confirming the nanoscale dimensions, while energy-dispersive x-ray spectroscopy spectra affirmed the high purity of the ZnO films, rich in Zn and O elements. Sensor tests demonstrated the ZnO sensor’s high sensitivity to low concentrations of volatile organic compounds such as ethanol, formaldehyde, methanol, and acetone. Notably, at an operational temperature of 300 °C, the sensor exhibited a remarkable response to 5 ppm of each gas, with the following response and response/recovery times: for methanol, 11.47 and 36 s/57 s; for acetone, 11.54 and 25 s/52 s; for formaldehyde, 0.79 and 53 s/58 s; and for ethanol, 3.88 and 9 s/59 s.

Enhancement of mechanical and ferromagnetic properties of Cd0.4Mn0.6XO nanocomposites (X=ZnO, SnO, CuO, Al2O3, Fe2O3, CoO, NiO)

Structural, mechanical and ferromagnetic characteristics of hydrothermally synthesized Cd0.4Mn0.6XO nanocomposites were investigated. The characterization of Cd0.4Mn0.6XO was accomplished using XRD, TEM, FTIR, photoluminescence and VSM techniques. The XRD showed the formation of monoclinic Cd2Mn3O8 alongside other phases. The crystallite size has no systematic trend against the valence state of ions. The particle size has minimum value (9.75 nm) for ZnO, and maximum values of 31.39 nm and 35.61 nm were observed for Al2O3 and Fe2O3, respectively. Similarly, typical enhancements are achieved for the mechanical and ferromagnetic parameters, e.g. they are increased when ZnO is replaced by Al2O3 and significantly enhanced by Fe2O3. In contrast, they were reduced by the other X, but they are still higher than ZnO. The photoluminescence of Cd0.4Mn0.6XO shows violet, blue, green, and orange emissions. The reported results indicate a strong correlation between the mechanical and ferromagnetic properties of nanocomposites against the particle/crystallite sizes and valence state.

Structural and optical studies of annealed zirconia nanocrystals: Phase transformations, defect dynamics, and magnetic behaviour

The present study is a continuation of our previous work, where we synthesized and characterized t-ZrO2 nanocrystals through the combustion method. Further, t-ZrO2 nanocrystals are annealed at 600, 900, 1200, and 1400°C and characterized through XRD, Raman, FESEM, XPS, photoluminescence (PL), and thermoluminescence (TL) techniques. XRD and Raman patterns reveal that the as-synthesized ZrO2 nanocrystals exhibit a tetragonal phase, and annealing at different temperatures induces phase transformations. Annealing at 600 °C restores the metastable nature of the tetragonal phase, although monoclinic nucleation is visualized through Raman spectroscopy. Annealing at higher temperatures leads to a complete transformation into the monoclinic phase. FESEM micrographs reveal extensive crystal growth and consolidation upon annealing. XPS analysis shows a reduction in the binding energies of the Zr 3d doublet due to the removal of lattice oxygen and the formation of oxygen vacancies upon annealing. The annealing of the synthesized material at 1400 °C induced a transformation to ferromagnetic behaviour at 300 K, with increased saturation magnetization (Ms) and coercivity (Hc), reflecting the stabilization of magnetic ordering and residual defects in the grain boundary. PL responses confirm the formation of luminescent defects in the crystal lattice. The TL response varies with the crystalline phase, annealing temperature, and radiation dose, suggesting defect creation, migration, and localization in the lattice. Overall, the study provides valuable insights into the structural and optical properties of ZrO2 nanoparticles annealed at different temperatures.

Effect of Dopant Concentration on Luminescence Properties of Na3Ca2(SO4)3F: RE (RE = Eu3+, Dy3+) Phosphor for Solid-State Lighting.

A fluoride material phosphor doped with rare earth ions Eu3+ and Dy3+ was studied for its photoluminescence (PL) properties. The material was synthesized using a combustion method and characterized using X-ray diffraction (XRD) and PL techniques. The Na3Ca2(SO4)3F: Eu3+ phosphor exhibits two distinct peaks at 593 nm (orange) and 615 nm (red) at an excitation wavelength of 395 nm. The PL excitation spectrum of the Na3Ca2(SO4)3F: Dy3+ phosphor showed series of peaks, corresponding to the 4f → 4f transitions of Dy3+ ions. Under 350-nm excitation, the PL emission spectrum revealed two prominent bands one at 483 nm (blue region) due to the 4F₉/₂ → 6H₁₅/₂ transition, and another at 573 nm (yellow region) resulting from the 4F₉/₂ → 6H₁₃/₂ transition. These blue and yellow emissions suggest potential applications in solid-state lighting, particularly for mercury-free excitation sources. Rare earth-doped Eu3+/Dy3+ materials exhibit highly efficient PL properties, making them suitable candidates for white light-emitting diodes (LEDs) or other solid-state lighting phosphors.

Needle Tip Tracking through Photoluminescence for Minimally Invasive Surgery.

Minimally invasive surgery continues to prioritize patient safety by improving imaging techniques and tumor detection methods. In this work, an all-optical alternative to the current image based techniques for in vitro minimally invasive procedures has been explored. The technique uses a highly fluorescent marker for the surgical needle to be tracked inside simulated tissues. A series of markers were explored including inorganic (Perovskite and PbS) and organic (carbon dots) nanoparticles and organic dye (Rhodamine 6G) to identify layers of different stiffnesses within a tissue. Rhodamine 6G was chosen based on its high fluorescence signal to track 3D position of a surgical needle in a tissue. The needle was tracked inside homogeneous and inhomogeneous gelatin tissues successfully. This exploratory study of tissue characterization and needle tip tracking using fluorescent markers or photoluminescence technique show potential for real-time application of robot-assisted needle insertions during in vivo procedures.

Unlocking Interfacial Interactions of In Situ Grown Multidimensional Bismuth‐Based Perovskite Heterostructures for Photocatalytic Hydrogen Evolution

AbstractTo combat the energy crisis and environmental pollution, developing renewable energy technology such as hydrogen (H2) production is necessary. The sulfur–iodine thermochemical cycle has high commercial potential in conducting hydrogen iodide (HI) splitting for H2 generation, but it requires high‐temperature conditions. In comparison, photocatalytic HI splitting of halide perovskites is non‐polluted and low‐cost for H2 production at room temperature. Herein, an in situ constructed multidimensional bismuth (Bi)‐based 3D/2D EDABiI5/MA3Bi2I9 perovskite heterojunction is developed first by synergistically integrating dimensionality control with heterostructure engineering. Accordingly, the optimal EDABiI5/MA3Bi2I9 without any co‐catalysts exhibits the H2 evolution rate of 213.63 µmol h−1g−1 under irradiation. Equally importantly, interfacial dynamics of solid/solid and solid/liquid interfaces play a crucial role in photocatalytic performance. Therefore, using temperature‐dependent transient photoluminescence and electrochemical voltammetric techniques, it is confirmed that the exciton transportation of EDABiI5/MA3Bi2I9 is accelerated by stronger electronic coupling arising from an enhanced overlap of electronic wavefunctions. Moreover, the effective diffusion coefficient and electron transfer rate of EDABiI5/MA3Bi2I9 demonstrate efficient heterogeneous electron transfer, resulting in improved photocatalytic hydrogen production. Consequently, the in situ formation of perovskite heterostructures studied by a combination of photophysical and electrochemical techniques provides new insights into green hydrogen evolution and interfacial interaction dynamics for commercial applications of solar‐to‐fuel technology.

Spectroscopic, vibrational and structural insights into LaYbO3:Pr3+ and LaLuO3:Pr3+,Tb3+ perovskites at ambient and high-pressure conditions

The interlanthanide perovskites LaYbO3:Pr3+ and LaLuO3:Pr3+,Tb3+ were synthesized by a solid-state reaction and characterized at ambient conditions by means of X-ray diffraction (XRD), Raman spectroscopy and photoluminescence techniques. XRD measurements have shown that the synthesis method provided samples with pure perovskite phase (space group Pnma) for LaYbO3, while in the case of the LaLuO3 compound small traces of Lu2O3 could be found after several annealing. Up to 13 Raman active modes were observed in the Raman spectra of the studied perovskites and theoretical calculations performed for LaYbO3 allowed to assign their symmetry. Regarding their optical properties, the emission from Tb3+ ions at B sites of the ABO3 perovskite could be distinguished. Moreover, NIR emission from Pr3+ was observed in the LaLuO3 perovskite at ∼1000 nm and 1250–1600 nm. Emission in these spectral regions could be relevant for Si-based solar cell applications and fiber optic amplifiers, respectively. Moreover, the stability of both perovskites under high-pressure conditions has been studied spectroscopically, finding that LaYbO3 is stable up to 19 GPa and that LaLuO3 undergoes a possible pressure-induced phase transition at ∼21–24 GPa. This makes LaLuO3 the first interlanthanide perovskite showing phase transition under 40 GPa.

Comprehensive analysis of organic dye doped metal-coordinated single crystals: A study of structural, optical, thermal, dielectric, piezoelectric and mechanical characteristics

Organic dye can induce positive changes in optical, mechanical and electrical properties of semi-organic single crystals. Single crystals of pure and 0.01 mol% SSY dye doped ZTS are grown from a slow evaporation solution technique. The structural properties of pure and SSY-dyed ZTS crystals are characterized using SCXRD and PXRD, confirming the maintenance of crystallinity and incorporation of dye molecules within the host lattice of ZTS crystal. Both ZTS crystals belong to orthorhombic crystal system with space group Pca21. The refined lattice parameters and cell volume of present pure ZTS crystal are a = 11.1723 Å, b = 7.7989 Å, c = 15.5357 Å, α = β = γ = 90°, V = 1353.6762 Å3. The intensity of all Raman peaks in ZTS is enhanced by the incorporation of dye. Optical spectroscopic UV–visible and photoluminescence techniques highlight the comparative studies of light absorption, energy bandgap, optical constants and fluorescence emission. An increment of 0.05 eV in optical bandgap is observed in dyed ZTS. The dielectric properties with variation in frequency range (23 Hz–10 MHz) at different temperature range (30–100 °C) are evaluated through impedance spectroscopy, showing an increase in dielectric constant around 15 % and reduction in dielectric loss, indicating potential for improved performance in electronic applications. A significant enhancement is observed in the piezoelectric coefficient (d33) in dyed ZTS single crystals. The d33 value of ZTS is increased from 2.75 to 2.95 pC/N by the doping of organic dye. Vickers micro-hardness tester is used to know the mechanical strength through micro-indentation, which illustrated an increase in the hardness nature of dyed ZTS single crystals. These findings provide a foundation for the future development of ZTS-based materials for technological applications, offering a promising route for the advancement of functional materials in the domain of piezoelectric and optoelectronic technologies.

Theoretical study of tip-enhanced photoluminescence of single molecule in nanocavity formed by apex protrusion and substrate

Tip-enhanced photoluminescence techniques, characterized by ultra-high detection sensitivity and spatial resolution, have exhibited unprecedented capabilities in exploring optoelectronic phenomena and unraveling intrinsic physical mechanism at the single-molecule level. To suppress the quenching of molecular luminescence and achieve high-resolution optical imaging, a rational design of the tip-substrate configuration is required. In this paper, we systematically investigate the tip-enhanced photoluminescence characteristics of single molecules located within the plasmonic nanocavity formed by the tip protrusion and the substrate from a theoretical perspective. The impacts of electron tunneling and electron-hole pair creation on localized electric field and quantum yield are discussed using the quantum correction model and nonlocal dielectric theory, respectively. The crucial roles of atomic-scale protrusion at the tip apex and the decoupling layer on the substrate in enhancing vertical and horizontal electric fields as well as quantum yields have been emphasized. The results indicate that in smaller sub-nanometer cavities, electron tunneling and nonlocal dielectric effects greatly weaken the electric field intensity and fluorescence quantum yield. Meanwhile, due to the sharp lightning rod effect, the presence of atomic-level protrusion at the tip apex can provide a strong and highly localized plasmonic field. We find that the added NaCl layer not only blocks charge transfer between molecules and the substrate but also effectively prevents fluorescence quenching. The maximum fluorescence and Raman enhancement factors near the tip apex approach up to 5 and 12 orders of magnitude, respectively, achieving sub-nanometer spatial resolution. Finally, compared to vertical electric field and dipole, sharp protrusion can excite a stronger horizontal electric field and couple with horizontal dipoles to yield a higher quantum yield, resulting in a three orders of magnitude higher in the fluorescence enhancement of horizontal dipole compared to the tip without protrusion. Our theoretical research not only confirms the experimental results of spectral enhancement with the proximity of the tip to the molecule in tip-enhanced photoluminescence, but also provides effective guidance for a deeper understanding of the mechanism of tip-enhanced fluorescence and Raman spectroscopy, as well as optimizing the experimental system.

In Situ PL Probes the Effect of 2D SnSe Nanosheets on the Crystallization Process of CsPbI2Br Perovskite Solar Cells.

Reducing defects in the active layer is important for improving the crystalline quality of all-inorganic perovskite solar cells (PSCs). Exploring novel additives is one of the most promising approaches to minimize active layer defects. In this work, two-dimensional (2D) SnSe nanosheets with excellent optoelectronic properties are prepared using an ultrasonic exfoliation method. The prepared 2D SnSe nanosheets are introduced into a CsPbI2Br precursor, which reduces the defect formation at grain boundaries and enhances the crystallinity of CsPbI2Br perovskites. We use the in situ photoluminescence (PL) technique to investigate the role of 2D materials in the crystallization process. The results show that SnSe nanosheets primarily shorten the grain boundary merging time and reduce the defect generation during the grain boundary merging stage, thereby regulating the crystallization of perovskite. In addition, SnSe nanosheets passivate uncoordinated Pb atoms at grain boundaries by Se atoms, further reducing the defect density in perovskite. As a result, PSCs exhibit a higher power conversion efficiency (PCE) of 14.24% and a Voc of 1.22 V. This study highlights the role of 2D materials in enhancing the crystalline quality and PCE of PSCs.

Efficient photocatalytic degradation of malachite green dye from wastewater using facilely synthesized ternary ZIF-8/Ag/Ag2S nanocomposite: Optimization by RSM (CCD)

The current study compares the photocatalytic potential of zeolitic imidazolate framework-8 (ZIF-8) with ZIF-8 nanocomposites doped with two forms of silver (referred to as AgNPs/ZIF-8 and AgNPs/Ag2S/ZIF-8). Their physicochemical characteristics were evaluated using Fourier-transform infrared, X-ray diffraction, energy-dispersive X-ray, Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), diffuse reflectance spectroscopy (DRS), photoluminescence (PL), photocurrent density, Mott-Schottky, and Brunauer Emmett Teller techniques. The photocatalytic activity of the composites was assessed for degradation of malachite green (MG) under visible light irradiation in a solar-based staircase photoreactor for the first time. The optimization of the photodegradation process was achieved by employing central composite design, 0.020 g of AgNPs/ZIF-8 and ZIF-8photocatalyst (in 20 ml of solution), MG Concentration of 7 mg/l, pH of 8, and the irradiation time of 50 min. The predicted model had R2 and R2adj correlation coefficients of 0.987 and 0.975 respectively, which showed experimental results were very close to the predicted values. The results indicated remarkable efficiency in both degradation and mineralization, achieving the degradation rate of up to 98.6 %, a high-rate constant value of 0.0701 min-¹, and an 80 % mineralization efficiency. AgNPs/Ag2S/ZIF-8 exhibited superior photocatalytic performance in comparison to both AgNPs/ZIF-8 and ZIF-8. Different scavengers were used in the experiment and demonstrated that O2− played a crucial role in the photodegradation of MG. Moreover, the nanocomposite AgNPs/Ag2S/ZIF-8 exhibited robust stability and could be repeatedly utilized up to five cycles without notable decline in efficacy, rendering it an environmentally sustainable photocatalyst with promising prospects for industrial utilization.

Photocatalyst based on composite of trimetallic metal-organic frameworks for efficient visible-light degradation in pharmaceutical pollutants abatement and process modeling using RSM

In this study, the facile synthesis of both monometallic Co- Metal-Organic Frameworks bimetallic Ni-Co-Metal-Organic Frameworks and trimetallic Ni-Co-Cu-Metal-Organic Frameworks was successfully accomplished with the chelation method. The prepared samples were characterized by using X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), N2 adsorption–desorption, Fourier transform infrared spectra (FTIR), differential reflectance spectroscopy (UV–vis-DRS), and photoluminescence (PL) techniques was undertaken to examine the physicochemical attributes of the synthesized composites. The photocatalytic efficiency of the antibiotic ceftazidime(CAZ) degradation was investigated under visible light irradiation in 100 min. Kinetic studies revealed a pseudo-first-order model (50.0143, 0.009, and 0.0057 min−1 for Co-MOF, Co-Ni-MOF, and Co-Ni-Cu-MOF, respectively). Response surface methodology (RSM) demonstrated satisfactory predictability for CAZ degradation efficiency. Under optimized conditions (pH 10, 0.25 g L−1 catalyst) more than 97.38 % for the 20.0 mg L−1 of CAZ was degraded. Furthermore, the recyclability and scavenging test for the catalyst was evaluated.

In situ hydrothermal synthesis of ZnCo2O4/ZnO nanocomposite: Structural, optical, electrochemical properties and photocatalytic performance under visible light

In this work, we report preparing zinc cobalt oxide/zinc oxide nanocomposite via a facial in situ hydrothermal route. The crystal structure of the as-synthesized products was characterized using X-ray diffraction (XRD). The XRD results confirmed the preparation of a ZnCo2O4/ZnO nanocomposite. A field emission scanning electron microscope (FESEM) was used to analyze the morphology of samples. From FESEM images of the nanocomposite, ZnCo2O4 nanoparticles have been decorated on ZnO hexagonal nanoplates. The optical properties of the as-prepared samples were characterized by UV–vis and photoluminescence (PL) techniques. Furthermore, we investigated the photocatalytic performance of the obtained samples for acid orange 7 (AO7) dye. It was found that the ZnCo2O4/ZnO nanocomposite exhibited appreciable photocatalytic performance under visible light irradiation in comparison with ZnCo2O4 and ZnO nanostructures.

Graphene Quantum Dots Based on Mechanical Exfoliation Methods: A Simple and Eco-Friendly Technique.

Graphene quantum dots (GQDs) are very precious, widely used, and face significant challenges in preparation methods. In this study, three mechanical methods are investigated for the preparation of GQDs. All of these methods are green, cost-effective, and simple. In fact, Graphite, as a main source of GQDs, is exfoliated and fragmented under mechanical forces by sonication and ball milling. This mechanical exfoliation method is effective for converting large flakes of graphite into quantum dots. Additionally, the proposed methods are simple and faster than other top-down GQD fabrication methods. High-power sonication is applied to graphene flakes by using the liquid-phase exfoliation method. The liquid phase consists of ethanol and water, which are completely eco-friendly. Exfoliation and fragmentation of graphene flakes are performed using different sonication and ball-milling times. The obtained results from the analysis of the synthesized GQDs exhibit pristine graphene's distinct structural, chemical, and optical properties. Several analyses, such as X-ray diffraction (XRD) and Fourier transform infrared spectroscopy, were applied to study the product structure. Dynamic light scattering (DLS) and field emission scanning electron microscopy (FESEM) were used to examine product size and morphology, which confirmed the nanosize of GQDs. The smallest observed size of GQDs is approximately 23 nm. It is estimated that 95% of the nanoparticles are between 0.001 and 0.1 μm in size (41 nm). The optical properties of GQDs were investigated by using ultraviolet-visible and photoluminescence (PL) techniques. The PL peak wavelength is approximately 610 nm. Eventually, the results proved that the combined use of two methods, ultrasonication and ball milling during liquid-phase exfoliation, will be a simple, cheap, and suitable method for the production of GQDs.