UV Vis Diffuse Reflectance Spectra Research Articles

2D/2D Bi2MoO6/CoAl LDH S-scheme heterojunction for enhanced removal of tetracycline: Performance, toxicity, and mechanism

In this paper, the two-dimensional (2D) layered CoAl LDH (CoAl) was coupled with Bi2MoO6 (BMO) nanoplate and used for tetracycline (TC) degradation. Based on the results of UV–visible diffuse reflectance spectrum (UV–vis DRS), Motty-Schottky curves, and in situ X-ray photoelectron spectroscopy (XPS), a novel 2D/2D Bi2MoO6/CoAl LDH S-scheme heterojunction photocatalyst was built. The photodegradation rate constant of TC by the optimized sample BMO/CoAl30 was 3.637 × 10−2 min−1, which was 1.26 times and 4.01 times higher than that of Bi2MoO6 and CoAl LDH, respectively. The favorable photocatalytic performance of the heterojunction was attributed to the increased interfacial contact area of the 2D/2D structure. Besides, the transfer of photogenerated electrons from Bi2MoO6 to CoAl LDH under the effect of the built-in electric field (BIEF) reduced the recombination of photogenerated carriers and further improved the photocatalytic performance. The reactive species of h+, ·O2−, and 1O2 exhibited critical roles to degrade TC molecules by reactive radicals capture experiments and electron spin resonance (ESR) tests. The intermediate products of TC degradation and toxicity of intermediates were analyzed by liquid chromatography-mass spectrometer (LC-MS) and Toxicity Estimation Software Tool (T.E.S.T). Additionally, the BMO/CoAl composite photocatalysts showed high stability and environmental tolerance during the testing of cycles and environmental impacts with various water sources, organic contaminants, initial pH, and inorganic ions. This work provides a new protocol for designing and constructing novel 2D/2D S-scheme heterojunction photocatalysts for wastewater treatment.

1D/2D Rod-sheet Shape Bi2S3 Photocatalyst for Photocatalytic Reduction Cr(VI) under Visible Light

The crystal structure and morphology of photocatalysts play a crucial role in determining their photocatalytic performance. In this study, we synthesized and investigated 1D/2D Bi2S3 as a potential visible-light-activated photocatalyst for the reduction of aqueous Cr(VI). The 1D/2D Bi2S3 was synthesized using hydrothermal synthesis technique by heating Bi2(H2O)2(SO4)2(OH)2 precursor and sodium sulfide at 190 ℃ for 24 h, where the molar ratio of Bi to S elements in the reaction reagents was changed from 1:6 to 2:3. The structure, composition, and optoelectronic properties of the prepared Bi2S3 were characterized using X-ray diffraction, UV-vis diffuse reflectance spectra, field emission scanning electron microscopy, electrochemical impedance spectra, and transient photocurrent. It is shown that the prepared orthorhombic Bi2S3 has full-spectrum photoresponsivity. Bi2S3-B with 1D/2D heterogeneous structure exhibits the lowest charge carrier transport resistance, and its photocurrent intensity is nearly twice that of Bi2S3-C. It demonstrates the highest photocatalytic activity in visible-light photocatalytic reduction of aqueous Cr(VI), with a reduction rate of 54.5% after 140 minutes of light exposure. According to the bandgap of Bi2S3 and radical scavenger experiments, a reaction mechanism for the photocatalytic reduction of Cr(VI) by Bi2S3 was proposed. Furthermore, the results highlight the economic and environmentally friendly nature of the hydrothermal synthesis method using homemade precursors, which allows for the regulation of Bi2S3 morphology and the enhancement of its visible photocatalytic activity. 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).

Nb:MnTeMoO6: Synthesis, structure and second-order nonlinear optical properties

MnTeMoO6 is an inorganic nonlinear optical material with potential applications in laser frequency conversion, due to its second harmonic generation efficiency. To enhance the properties of MnTeMoO6, an alternative method of Nb-doping with nonequivalent isomorphism has employed. Nb:MnTeMoO6 has been synthesized by solid-state reaction techniques at a Nb-doping ratio of 1–10 mol%. Powder X-ray diffraction, Raman spectra, UV–vis diffuse reflectance spectra and powder second harmonic generation efficiency of Nb:MnTeMoO6 have been investigated. Consequently, the results show that Nb:MnTeMoO6 have been synthesized by the solid-state reaction technique successfully. Nb:MnTeMoO6 with a single crystalline phase has a Nb-doping ratio that is less than or equal to 3 mol%. The band gap energies of Nb:MnTeMoO6 would increase with the Nb-doping. Interestingly, the UV absorption peak of the 2 mol% Nb:MnTeMoO6 resultant exhibits a blue shift. It is noteworthy that 1 mol% Nb:MnTeMoO6 exhibits a significant SHG response of approximately 0.96 pm/Vm (1.23 × MnTeMoO6).

Room temperature sensing of ammonia and formaldehyde gases through novel anisotype heterojunction of p-Co3O4/n-Gd0.1Ce0.9O2-δ as highly responsive and stable sensors

The development of the room temperature (RT) gas sensors is absolute need. Hydrothermally and sol-gel derived Co3O4 and Gd0.1Ce0.9O2-δ (GDC) were used to fabricate the novel heterostructures in the ratio of 1:1 Co3O4/GDC, 2:1 Co3O4/GDC and 1:2 Co3O4/GDC. These samples were scientifically analysed through X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM), Energy dispersive X-ray (EDX) spectra, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), Raman, UV–Vis-Diffuse reflectance spectra (DRS) and photoluminescence (PL). XRD, XPS together with FTIR and Raman spectra are the testimonial of the formation of Co3O4, GDC and their heterostructures. Interestingly, the performed gas sensing studies conclusively disclose that these sensors have adequate sensitivity to detect the tested gases at RT. Furthermore, O2− species played crucial role than O2− and O− in chemisorption and gas sensing mechanism. Additionally, 2:1 Co3O4/GDC and 1:2 Co3O4/GDC exhibited an enormous selectivity and highly responsive towards the detection of formaldehyde (CH2O) and ammonia (NH3), respectively. 2:1 Co3O4/GDC/1:2 Co3O4/GDC offered the high response (S) of 106.59/83.52 for CH2O/NH3 gas. In fact, the formation of anisotype p-n/n-p rather than isotype p-p/n-n junctions in 2:1 Co3O4/GDC and 1:2 Co3O4/GDC endowed these two heterostructures to exhibit quick response even at low ppm of selected gases. The outcome of this work might provide strategy for the design of novel sensing materials to detect multiple gases.

Syntheses, crystal structures, optical properties, antibacterial activity and DFT calculations of two tetrachlorocobaltate(II) salts with substituted methyl pyridinium

The syntheses, compositions, and structural analyses of two new organic-inorganic metal halides benzyl-2-methyl pyridinium tetrachlorocobaltate(II) [Bz-2-MePy]2[CoCl4](1) and benzyl-4-methyl pyridinium tetrachlorocobaltate(II) [Bz-4-MePy]2[CoCl4](2) were presented in this paper. Single-crystal X-ray diffraction analyses revealed that 1 and 2 crystallized in the monoclinic space group C2/c and the orthorhombic space group Pna21, respectively, composed of two [Bz-2-MePy]+/[Bz-4-MePy]+ cations and a [CoCl4]2− anion, in which the [CoCl4]2− anion displayed a tetrahedral geometry. Two crystals investigated by TG-DTA technique were stable up to 162.7 °C (1) and 226.3 °C (2), respectively. The HOMO–LUMO energy gaps and UV–vis diffuse reflectance spectra explained the charge transfer interactions between [CoCl4]2− cations and the [Bz-2-MePy]+/[Bz-4-MePy]+ cations. In addition, their low band gap values (1.88 eV in gas state and 1.65 eV in solid state for 1, 1.18 eV in gas state and 1.64 eV in solid state for 2) indicated the appropriateness of the crystals for optical applications. The first hyperpolarizabilities (βtot) of two salts were 459 and 70,000 times higher than the standard KDP crystal (βKDP = 6.85 × 10−31 esu), respectively. The antibacterial experiments demonstrated that both salts exhibited superior bactericidal activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus).

A simple sol–gel method for the synthesis of Pt co-catalyzed spinel-type CuFe2O4 for hydrogen production; the role of crystallinity and band gap energy

In this investigation, spinel-type copper ferrites (CuFe2O4) at different calcination temperatures (600–900 °C) were produced using a facile citric acid-assisted sol–gel method. The crystal structure, morphology, optical, and electrical properties of the as synthesized photocatalysts were comprehensively characterized. XRD and UV–vis diffuse reflectance spectra (UV–vis (DRS)) showed that the phase structure and the band gap energy of the copper ferrite are strongly correlated to the applied calcination temperature. TEM results investigated that the copper ferrites calcined at higher temperatures presented large particle sizes and crystallized very well. In addition, the photocatalytic activity was tested for hydrogen production in the presence of methanol, with and without Pt nanoparticles as a cocatalyst. The results indicated that the CuFe2O4 annealed at 900 °C (CuF-900) has higher hydrogen production activity than photocatalysts calcined at lower temperatures in the presence and absence of Pt, which is mainly assigned to the higher crystallinity, and narrower bandgap energy. Moreover, this study explained in more detail the role of Pt nanoparticles in enhancing the photocatalytic activity of CuF-900. This work introduces a new direction of thinking for the tetragonal phase structure as an efficient photocatalyst for hydrogen production.

Removal of chromium from aqueous solution by CLCh/Fe/MWCNT/TiO2-Ag magnetic composite film: Simultaneous Cr(VI) reduction and Cr(III) adsorption

A catalyst CLCh/Fe/MWCNT/TiO2-Ag film was prepared using multi-walled carbon nanotubes (MWCNT) impregnated with magnetic iron oxide and silver-doped titanium dioxide (TiO2-Ag), being deposited on crosslinked chitosan (CLCh). The physicochemical characterization of the catalyst was performed by various analytical techniques such as ICP-MS, XRD, FTIR, SEM, EDS, Raman spectroscopy, N2 adsorption/desorption and UV–Vis diffuse reflectance spectra (DRS). A solution of Cr(VI) (30 mg/L) was used in the evaluation of the photoreduction of (Cr(VI) to Cr(III)) using UV–visible light (filter cut-off for λ > 300 nm). The composite film allowed, when applied in a solution of 30 mg/L of Cr(VI) at pH 2, the removal and simultaneous photoreduction of 97 % of Cr(VI) to Cr(III) in 120 min. The cationic Cr(III) generated remains retained in the composite film by adsorption on the hydroxyl and carboxyl groups of MWCNTs. The CLCh/Fe/MWCNT/TiO2-Ag film can be mechanically removed from the aqueous solution or by magnetic attraction. In ten consecutive cycles of reuse, the CLCh/Fe/MWCNT/TiO2-Ag film showed an efficiency of 84 % in the photoreduction of Cr(VI).

Cu and Fe doped NiCo2O4/g-C3N4 nanocomposite ferroelectric, magnetic, dielectric and optical properties: Visible light-driven photocatalytic degradation of RhB and CR dyes

A novel Cu and Fe doped NiCo2O4/g-C3N4 nanocomposites were prepared with varying dopant concentrations via a precipitation and ultrasonication route. The resulting Ni1-xCuxCo2-yFeyO4/g-C3N4 nanocomposites were characterized by advanced techniques and effect of doping was investigated based on ferroelectric, dielectric, magnetic, electrical, optical and photocatalytic properties. The results confirmed the FCC spinel geometry of NiCo2O4 nanoparticles with a spherical shape (ranging from 18 to 32 nm). The absorption range in the visible region and the suppression of electron-hole recombination were investigated through UV–Vis diffused reflectance spectra and PL analysis. The Cu and Fe doping significantly influenced the dielectric properties and the AC conductivity of Ni1-xCuxCo2-yFeyO4/g-C3N4 nanocomposites was also increased with Cu and Fe substitution. The photocatalytic activity of doped Ni0.75Cu0.25Co1.5Fe0.25O4/g-C3N4 (NCCF3/g-CN) were evaluated for the removal of rhodamine B (RhB) and Congo red dyes under visible light irradiation. The NCCF3/gCN nanocomposite exhibited the dye removal of 89 % versus undoped nanocomposite (50 %). The rate constants for CR dye degradation were found to be 0.04366 and 0.1009 (min−1) for the NCCF3/gCN nanocomposite and undoped nanocomposite NiCo2O4/gC3N4 (NCO/gCN), respectively. The efficient separation of charge carriers was facilitated by the migration of photo-induced electrons from the g-C3N4 surface to the NiCo2O4. The influence of pH and catalyst dose on the kinetics of photocatalytic activity revealed a significant effect on the dye degradation rate. The results indicate that the NiCo2O4/g-C3N4 shows a promising potential for photocatalytic removal of dyes under visible light illumination, which could be employed for the removal of dyes from the effluents.

Electrostatic Self-Assembled Synthesis of Amorphous/Crystalline g-C3N4 Homo-Junction for Efficient Photocatalytic H2 Production with Simultaneous Antibiotic Degradation.

g-C3N4 has been regarded as a promising photocatalyst for photo-reforming antibiotics for H2 production but still suffers from its high charge recombination, which has been proven to be solvable by constructing a g-C3N4 homo-junction. However, those reported methods based on uncontrollable calcination for preparing a g-C3N4 homo-junction are difficult to reproduce. Herein, an amorphous/crystalline g-C3N4 homo-junction (ACN/CCN) was successfully synthesized via the electrostatic self-assembly attachment of negatively charged crystalline g-C3N4 nanorods (CCN) on positively charged amorphous g-C3N4 sheets (ACN). All the ACN/CCN samples displayed much higher photo-reforming of antibiotics for H2 production ability than that of pristine ACN and CCN. In particular, ACN/CCN-2 with the optimal ratio exhibited the best photocatalytic performance, with a H2 evolution rate of 162.5 μmol·g-1·h-1 and simultaneous consecutive ciprofloxacin (CIP) degradation under light irradiation for 4 h. The UV-vis diffuse reflectance spectra (DRS), photoluminescence (PL), and electrochemical results revealed that a homo-junction is formed in ACN/CCN due to the difference in the band arrangement of ACN and CCN, which effectively suppressed the charge recombination and then led to those above significantly enhanced photocatalytic activity. Moreover, H2 was generated from the water reduction reaction with a photogenerated electron (e-), and CIP was degraded via a photogenerated hole (h+). ACN/CCN exhibited adequate photostability and reusability for photocatalytic H2 production with simultaneous CIP degradation. This work provides a new idea for rationally designing and preparing homo-junction photocatalysts to achieve the dual purpose of chemical energy production and environmental treatment.

Insights into the visible light induced photocatalytic degradation of Acid Violet dye using carbon functionalized Ag2WO4 nanoparticles

The study investigates the photodegradation of Acid Violet 7, a commonly used azo dye in textile industries, using carbon functionalized Ag2WO4 nanostructures as a photocatalyst. The materials were characterised by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectra and UV-Vis diffuse reflectance spectra. In this research work, carbon functionalized Ag2WO4 nanostructures is synthesized and evaluated for its effectiveness in degrading Acid Violet 7 under visible light irradiation. The degradation process is explored by investigating various parameters such as catalyst loading and initial dye concentration. It is worth mentioning that the 75 % degradation is achieved in 30 minutes. The results demonstrate the photocatalytic activity of carbon functionalized Ag2WO4 nanostructures in degrading Acid Violet 7, highlighting its potential for efficient treatment of dye-contaminated wastewater. The primary active species involved in the degradation process is identified to be the hydroxyl radical. The modification of Ag2WO4 nanostructures with carbonaceous material enhances its photocatalytic performance by improving the light absorption and preserves the structural integrity of the nanostructures. The carbon functionalized nanostructures investigated in this research holds great promise towards the development of sustainable and effective photocatalytic system for environmental remediation.

A new zero-dimensional (0D) hybrid bismuth (III) halide: Synthesis, crystal structure, thermal analysis, photophysical properties and DFT calculations

Low-dimensional organic-inorganic hybrid Bi(III) halides, with organic N, O-heterocycles, are promising solid-state photoluminescent materials, but are underexplored. In this work, we present the synthesis and characterization of a novel bismuth (III) hybrid salt, namely (C8H12NO)4[Bi2Cl10] (referred as (1)). (1) was synthesized using a solvent-evaporation method and extensively characterized using various techniques. The crystal structure of (1) was determined to be zero-dimensional (0D). In this structure, the individual bioctahedral [Bi2Cl10]4− dimers, which share edges, are completely isolated from each other. These dimers are separated by large 4-methoxybenzylammonium cations (C8H12NO)+. The latter are crucial for the crystal structural stability by balancing [Bi2Cl10]4-dimer charges and maintaining overall integrity. Solid-state diffuse reflectance UV–Vis spectrum demonstrates that (1) is a semiconductor with a band gap of 3.32 eV. Its photoluminescence spectrum exhibits intense blue emission when exposed to UV light, with CIE chromaticity coordinates of (0.22, 0.21). Theoretical calculations suggest that the emission with multiple centers originates both from a charge transition between (C8H12NO)+ and Bi2Cl104− ions and from excited-state proton transfer (ESPT) processes related to fluorescence properties. These ESPT processes occur through C–H…π and C–H…O intermolecular hydrogen bonding between the organic cations.

A new TBC material: (La0.2Gd0.2Y0.2Sm0.2Ce0.2)2Zr2O7 high-entropy oxide

In this study, (La0.2Gd0.2Y0.2Sm0.2Ce0.2)2Zr2O7((LGYSC)ZO)), as a new type of thermal barrier coating material, was designed and synthesized. The lattice structure, microstructure, optical, thermophysical, and mechanical properties of the (LGYSC)ZO high-entropy oxide were also investigated. The results showed that a phase-pure pyrochlore-structure (LGYSC)ZO high-entropy oxide, which has a uniform elemental distribution at high temperatures, was successfully synthesized. In addition, the UV–Vis diffuse reflectance spectra results show that (LGYSC)ZO high-entropy oxide has direct and indirect bandgap widths of 3.10eν and 2.51eν, respectively. Infrared (IR) spectra of (LGYSC)ZO high-entropy oxide patterns were measured. The infrared spectra results show that the (LGYSC)ZO high-entropy oxide has better high temperature thermal radiation shielding performance than yttria stabilized zirconia(YSZ). According to the measured result by laser flash method, the thermal conductivity of (LGYSC)ZO high-entropy oxide is at range from 1.18 W m−1 K−1 to 1.37 W m−1 K−1 in the temperature regime from 200 °C to 1000 °C after porosity correction. The coefficient of thermal expansion (CTE) of (LGYSC)ZO high-entropy oxides is at range from about 7.79 × 10−6 k−1 to 11.1 × 10−6 k−1 corresponding temperature from 90 °C to 1000 °C. The mechanical properties of (LGYSC)ZO high-entropy oxides were also investigated, and the hardness and fracture toughness of (LGYSC)ZO high-entropy oxide were 6.61 GPa and 1.27 MPa m1/2, respectively. Therefore, the results indicate that (LGYSC)ZO has excellent properties as a promising thermal barrier coating material.

Effect of Dy3+ substitution on the structural and optical properties of BaWO4 nanoparticles-Visible emissions for optoelectronic applications

Barium tungstate (BaWO4) and dysprosium-doped barium tungstate (BaWO4:Dy) nanophosphors were synthesized using a chemical precipitation method. The crystal phase and structural parameters of the BaWO4 and BaWO4: Dy samples were assessed using X-ray diffraction (XRD) analysis. The morphological characteristics were examined by transmission electron microscopy (TEM). The optical properties were investigated using UV–visible diffuse reflectance spectra and photoluminescence spectroscopy. The structural analysis verifies that the samples possess a tetragonal scheelite structure. The introduction of Dy atoms through doping induces alterations in both the size and form of the particles. The optical band gap of the sample exhibits a decrease upon the introduction of Dy atoms into the BaWO4 sample,providing confirmation of the development of intermediate energy levels. The photoluminescence spectra within the visible region are analyzed, confirming its potential applications in optoelectronic systems.

Tungstophosphate Intercalated ZnAl Layered Double Hydroxide for Adsorptive and Visible Light Driven Photocatalytic Decolourisation of Organic Dyes

Tungstophosphate (PW<sub>12</sub>O<sub>40</sub><sup>3-</sup>) intercalated ZnAl-Layered double hydroxide (ZnAl-PW<sub>12</sub>) was successfully synthesized through the rehydration of calcined LDH. Chemical analyses and characterizations by powder XRD, FT-IR, and Diffuse reflectance UV-Vis spectra confirmed the intercalation of PW<sub>12</sub>O<sub>40</sub><sup>3-</sup> ions equivalent to ~80% of the residual positive charge in the brucite layer. The efficiency of ZnAl-PW<sub>12</sub> for decolourisation of four structurally different cationic/anionic dyes through simultaneous adsorption and photocatalysis under visible light irradiation was assessed. Under identical conditions, the photocatalytic efficiency of the ZnAl-PW<sub>12</sub> catalyst was found to be much higher than that of calcined ZnAl-LDH, indicating the promoting effect of PW<sub>12</sub>O<sub>40</sub><sup>3-</sup> ion. Moreover, the loss of costly polyoxometallate (POM) could be avoided by intercalating the POM ion in the interlayer of LDH, which can facilitate the use of synthesized catalysts for repeated cycles.

Chromophores' Contribution to Color Changes of Thermally Modified Tropical Wood Species.

This work examines the effect of thermal modification temperature (180, 200, and 220 °C) in comparison with reference (untreated) samples on selected optical properties of six tropical wood species-Sp. cedar (Cedrala odorata), iroko (Chlorophora excelsa), merbau (Intsia spp.), meranti (Shorea spp.), padouk (Pterocarpus soyauxii), and teak (Tectona grandis). The main goal is to expand the existing knowledge in the field of wood thermal modification by understanding the related degradation mechanisms associated with the formation of chromophoric structures and, above all, to focus on the change in the content of extractive substances. For solid wood, the CIELAB color space parameters (L*, a*, b*, and ΔE*), yellowness (Y), ISO brightness, and UV-Vis diffuse reflectance spectra were obtained. Subsequently, these wood samples were extracted into three individual solvents (acetone, ethanol, and ethanol-toluene). The yields of the extracted compounds, their absorption spectra, and again L*, a*, b*, ΔE*, and Yi parameters were determined. With increasing temperatures, the samples lose brightness and darken, while their total color difference grows (except merbau). The highest yield of extractives (mainly phenolic compounds, glycosides, and dyes) from thermally modified samples was usually obtained using ethanol. New types of extractives (e.g., 2-furaldehyde, lactones, formic acid, some monomer derivatives of phenols, etc.) are already created around a temperature of 180 °C and may undergo condensation reactions at higher temperatures. For padouk, merbau, teak, and partially iroko modified at temperatures of 200 and 220 °C, there was a detected similarity in the intensities of their UV-Vis DR spectra at the wavelength regions corresponding to phenolic aldehydes, unsaturated ketones, quinones, stilbenes, and other conjugated carbonyl structures. Overall, a statistical assessment using PCA sorted the samples into five clusters. Cluster 3 consists of almost all samples modified at 200 and 220 °C, and in the other four, the reference and thermally modified samples at 180 °C were distributed. The yellowness of wood (Y) has a very high dependence (r = 0.972) on its brightness (L*) and the yellowness index of the extractives in acetone Yi(Ac), whose relationship was described by the equation Y = -0.0951 × Y(Ac) + 23.3485.

Facile synthesis of Pd nanoparticles dispersed polypyrrole-carbon black/NiO nanocomposite with enhanced photocatalytic degradation of colored and colorless organic pollutants

Creation and designing of efficient visible-light responsive photocatalysts requires highly precise and extremely determined efforts in order to obtain material with promising properties and efficient transfer of charge carriers. In this work, we aim to develop and manufacture a distinct visible light photocatalyst consisting of NiO nanostructures, polypyrrole doped carbon black (PPyC) and Pd nanoparticles for wastewater treatment. The Pd NPs and PPyC doped NiO trio photocatalyst was developed via simple ultrasonication and photoreduction methods. XRD analysis showed that NiO has crystalline face centered cubic structure while the successful development of ternary photocatalyst was smoothly confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FTIR) studies. Transmission electron microscopy (TEM) images showed that NiO possessed fine irregular shape particles with size ranging from 20 to 50 nm grown abundantly in huge density, while the PPyC exhibited beads shape structures interconnected with each other giving chain like appearance. The diffuse reflectance UV–vis spectra showed red shift and lowering in bandgap upon Pd and PPyC doping. The newly produced Pd-PPyC@NiO photocatalyst has been exploited for the photocatalytic removal of colorless insecticide imidacloprid and colored methylene blue (MB) dye under visible light irradiation. The newly created Pd-PPyC@NiO photocatalyst removed 96.0% of imidacloprid just in 20 min representing ⁓ 3 times more efficient than bare NiO. Furthermore, Pd-PPyC@NiO photocatalyst was exceptionally well towards the destruction of MB under same visible light source, indicating its potential use in photocatalysis.

Synthesis, crystal structure, characterization, effective photocurrent response and photodegradation of a silver(I) diphosphine 3D supramolecular structure

A new three-dimensional (3D) supramolecular compound, [Ag(dppe)(CF3COO)]n (1), was prepared by using Ag(I) as the silver source and dppe as the organic ligand through the self-assembly approach. The bridging dppe ligand makes compound 1 appear as a one-dimensional (1D) wavy chain consolidated by the intramolecular hydrogen bonds. Two adjacent 1D chains are expanded to a two-dimensional (2D) layer passing through the intermolecular CH···π interaction between the dppe ligands, and the 2D layers further weave into a 3D supramolecular structure via another intermolecular CH···π interactions between the dppe ligands. The precise structure of 1 was determined by single crystal X-ray diffractometer (SCXRD), and it was well-characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analysis (TG) and differential thermogravimetry analysis (DTG), and UV–vis diffuse reflectance spectrum. In addition, the photocurrent response, electrochemistry characteristic and photodegradation of 1 were investigated. The degradation efficiency (82 %) of 1 as catalyst to degrade methylene blue (MB) was significantly higher than that without catalyst.

Structural and luminescent performance and optical thermometry of Pr3+ doped SrWO4 down-conversion phosphors

A series of Pr3+ doped SrWO4 phosphors were synthesized using solid-state reaction routes. The phase composition, photoluminescence and temperature sensitivities of as-prepared materials were investigated. Rietveld refinement of measured XRD data was applied to analyze the lattice parameters. The optical transition was elaborated using UV–visible diffuse reflectance spectra and photoluminescence spectra. The photoluminescence measurements confirmed the strong visible light emission from the developed phosphors under both UV excitation at 250 nm and blue excitation at 450 nm. Notably, the maximum emission intensity was observed at a Pr3+ doping concentration of 2 mol%. Furthermore, the fluorescence intensity ratio (FIR) technique was employed, focusing on the emissions originating from the 3P0 and 1D2 state of Pr3+ within the temperature range of 298–598 K. Two FIR groups were adopted in this case, which can verify each other to achieve self-calibration. Typically, SrWO4:0.02Pr3+ exhibited remarkable performance as a temperature sensor, displaying an absolute sensitivity (Sa) of 3.11%K−1 and a relative sensitivity (Sr) of 0.81%K−1. As a result, the significant temperature-dependent PL and remarkable down-conversion luminescence make the SrWO4:Pr3+ material a promising candidate for optical thermometers and UV to visible converters of solar cell applications.

Photocatalytic membrane coated with α-Fe2O3/Fe3O4 for enhanced filtration performance and antifouling property in surface water treatment

A photocatalytic membrane coated with α-Fe2O3/Fe3O4 nanoparticles has been developed to address the challenges of membrane fouling and organic removal in the treatment of natural surface water. The photocatalytic and filtration properties of the membranes were investigated through a variety of methods. The successful preparation of iron oxide was confirmed by UV–vis diffuse reflectance spectra and X-ray diffractometry, with α-Fe2O3 identified as the primary photocatalytic agent. A commercial ultrafiltration (UF) membrane was employed as a comparison to evaluate the photocatalytic performance and filtration properties of the modified membrane. Results showed that the photocatalytic membrane achieved better removal rates for UV254 (22.0%) and specific fluorescent organic compounds, such as component 2 (19.38%) and component 3 (16.89%), compared to the control group. Furthermore, both irreversible and reversible fouling resistances of the prepared membranes were significantly lower than that of the control group, with reductions of 39.4% and 50.2%, respectively. The membrane coated with α-Fe2O3/Fe3O4 nanoparticles exhibited moderate removal of protein-like and terrestrially derived humic-like fluorescent organics while controlling membrane fouling. Although the α-Fe2O3/Fe3O4 nanoparticles-coated photocatalytic membrane demonstrated good anti-fouling properties, the removals of organic matters were not as effective as anticipated due to the shorter hydraulic retention time. This study provides valuable insights for enhancing pollutant degradation and anti-fouling properties of membranes through the utilization of solar photocatalytic α-Fe2O3/Fe3O4 surface-modified membranes in the treatment of natural surface water.

Synthesis and Application of a Fe3O4/Ag3PO4/g-C3N4 Magnetic Composite Photocatalyst for Sulfonamide Antibiotics Degradation

In this study, a novel Fe3O4/Ag3PO4/g-C3N4 magnetic composite photocatalyst was successfully synthesized, tailored specifically for the visible light-driven photocatalytic degradation of sulfonamide antibiotics, more precisely, sulfamethazine (SMZ). To analyze the fabricated samples, characterization techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), photoluminescence spectroscopy (PL), and UV-vis diffuse reflectance spectra (UV-vis) were systematically employed. The composite showcased efficient visible-light absorption and charge separation, with its peak photocatalytic performance recorded at a solution pH value of 6.0. Significantly, the Fe3O4/Ag3PO4/g-C3N4 magnetic composite photocatalyst displayed excellent stability and recyclability, consistently maintaining a high degradation efficiency of over 97% even after five consecutive cycles. Further experimentation with radical scavengers confirmed a significant decrease in photocatalytic activity, establishing that superoxide radicals (•O2−) and photo-generated holes (h+) are the primary active species during the degradation of SMZ. Overall, it provides a crucial understanding regarding the photocatalytic decomposition of sulfonamide antibiotics using magnetic composite photocatalysts. It also emphasizes the promising potential of the Fe3O4/Ag3PO4/g-C3N4 composite for tangible applications in environmental remediation.