UV Vis Diffuse Reflectance Spectroscopy Research Articles

Characterization of Ti-MOF derived TiOx assembled with different carboxylic acid organic ligands and differences in their CO2 photothermal catalytic reduction performance

The photothermal catalytic conversion of carbon dioxide into fuel gas is a promising technology for simultaneously addressing environmental and energy challenges. Currently, widely used metal oxide-based catalysts, such as TiO2, often show significant performance variations depending on the preparation methods. Therefore, developing metal oxides with superior photothermal catalytic properties is a key approach to producing high-performance composite catalysts. This article discusses the preparation of high-performance metal oxide catalysts derived from MOFs. By regulating four different carboxylic acid organic ligands to assemble with Ti-O clusters into various precursors, TiOx was derived and prepared. Techniques such as XRD, infrared spectroscopy, XPS,TEM, SEM, N2 adsorption–desorption analysis, CO2-TPD, H2-TPR, PL spectrum, Raman spectra, UV–visible diffuse reflectance spectroscopy, photoelectrochemical characterization, and others were used to comprehensively explore the structure, surface properties, and photoelectric properties of the derivatives influenced by the organic ligands. Derivatives were subjected to photothermal catalytic reduction of carbon dioxide in hydrogen rich gas without metal loading, and the intermediate pathway of the reaction was investigated through in situ DRIFTS spectra. Research has shown that organic ligands have a significant impact on the morphology, surface properties, and optoelectronic properties of derivatives. The TiOx derived from the precursor assembled with 2-aminoterephthalic acid as an organic ligand has a larger specific surface area, abundant oxygen vacancies, excellent photoelectric conversion ability, and surface electron migration performance. Under the condition of coupled light irradiation at 400 ℃, a CO yield of 4944.81 μmol/g was achieved, with a selectivity of 99.89 %. The reaction follows the formate pathway. This study provides valuable reference for the development and modification of high-performance TiO2 based catalysts.

Modulating Electronic Structure of MoS2 Nanosheets by Sulfide Enrichment‐Induced Vacancies for Enhanced Photocatalytic Hydrogen Production

AbstractEnhancing photocatalytic activity by changing the electronic structure of the catalyst is an effective strategy. 2H‐MoS2 has semiconductor properties, and its unsaturated side S atom is the main active site for its photocatalytic activity. However, due to the weak S─H bond energy, its hydrogen adsorption capacity is weak. In this work, the electronic structure of MoS2 is adjusted by S‐rich treatment, resulting in the formation of Mo vacancy (MoS2‐VMo). The level of Mo vacancies was assessed using UV–vis diffuse reflectance spectroscopy (UV–vis DRS). As these vacancies can capture certain photogenerated electrons, thereby reducing the recombination of electron‐hole pairs. Through DFT calculation, it is found that the antibonding orbital electron filling of MoS2‐VMo is weakened, the bond energy of S─Mo bond is weakened, and the bond energy between S─H bond is enhanced, which is more conducive to proton adsorption. The photocatalytic activity for hydrogen evolution of MoS2‐3, which underwent the optimal S‐rich treatment, achieved a remarkable rate of 2404.6 µmol g−1 h−1 in dye eosin Y (EY) sensitization system, significantly surpassing that of MoS2 lacking the S‐enriched treatment. This study introduces a novel concept for enhancing the photocatalytic hydrogen evolution performance of metal sulfides via defect engineering.

TiO2/NiFe2-xCexO4/rGO ternary magnetic nanocomposite as separable and recyclable photocatalyst

This study investigates the synthesis and application of a TiO2/NiFe2-xCexO4/rGO ternary magnetic nanocomposite as an efficient and recyclable photocatalyst. The nanocomposite was characterized using Fourier-transform infrared(FTIR), X-ray diffraction(XRD), Field emission scanning electron microscopy(FE-SEM), magnetic measurements, UV–Vis diffuse reflectance spectroscopy(DRS), and X-ray photoelectron spectroscopy (XPS). FTIR analysis confirmed the formation of the inverse spinel cubic structure, with significant vibrational bands related to metal–oxygen complexes. XRD patterns showed successful incorporation of Ce3+ ions into the NiFe2O4 lattice, with shifts in diffraction peaks indicating changes in crystallite size and lattice parameters. FE-SEM images revealed a well-dispersed distribution of TiO2 and NiFe2O4 nanoparticles on the reduced graphene oxide (rGO) surface, enhancing the nanocomposite’s structural integrity. Energy dispersive X-ray(EDX) analysis demonstrated the presence of Ti, Ni, Fe, Ce, O, and C elements in the ternary nanocomposite without impurities, confirming the high purity of the material. Magnetic measurements indicated increased magnetization due to Ce3+ doping. DRS revealed optical band gaps (Bg), and XPS provided detailed insights into the surface chemical composition and valence states. XPS analysis confirmed the presence of Ni2+, Fe3+, Ti4+, and Ce3+ ions, and verified the reduction of graphene oxide to rGO. Importantly, the XPS data also indicated a reduction in the binding energy of oxygen species, which suggests effective electron trapping. The photocatalytic performance was assessed by the degradation of methylene blue (MB) under UV and Vis light. The TiO2/NiFe2-xCexO4/rGO nanocomposite demonstrated superior photocatalytic activity with high degradation rates. The enhanced photocatalytic efficiency is attributed to efficient electron trapping, which reduces electron-hole recombination. Furthermore, the nanocomposite showed excellent reusability, maintaining high photocatalytic efficiency over multiple cycles of use, which underscores its potential for practical applications in environmental remediation.

Efficient Catalytic Reduction of Organic Pollutants Using Nanostructured CuO/TiO2 Catalysts: Synthesis, Characterization, and Reusability

The catalytic reduction of organic pollutants in water is a critical environmental challenge due to the persistent and hazardous nature of compounds like azo dyes and nitrophenols. In this study, we synthesized nanostructured CuO/TiO2 catalysts via a combustion technique, followed by calcination at 700 °C to achieve a rutile-phase TiO2 structure with varying copper loadings (5–40 wt.%). The catalysts were characterized using X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared (ATR–FTIR) spectroscopy, thermogravimetric analysis-differential thermal analysis (TGA–DTA), UV-visible diffuse reflectance spectroscopy (DRS), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDS). The XRD results confirmed the presence of the crystalline rutile phase in the CuO/TiO2 catalysts, with additional peaks indicating successful copper oxide loading onto TiO2. The FTIR spectra confirmed the presence of all the functional groups in the prepared samples. SEM images revealed irregularly shaped copper oxide and agglomerated TiO2 particles. The DRS results revealed improved optical properties and a decreased bandgap with increased Cu content, and 4-Nitrophenol (4-NP) and methyl orange (MO), which were chosen for their carcinogenic, mutagenic, and nonbiodegradable properties, were used as model organic pollutants. Catalytic activities were tested by reducing 4-NP and MO with sodium borohydride (NaBH4) in the presence of a CuO/TiO2 catalyst. Following the in situ reduction of CuO/TiO2, Cu (NPs)/TiO2 was formed, achieving 98% reduction of 4-NP in 480 s and 98% reduction of MO in 420 s. The effects of the NaBH4 concentration and catalyst mass were investigated. The catalysts exhibited high stability over 10 reuse cycles, maintaining over 96% efficiency for MO and 94% efficiency for 4-NP. These findings demonstrate the potential of nanostructured CuO/TiO2 catalysts for environmental remediation through efficient catalytic reduction of organic pollutants.

Facile synthesis and characterization of zinc molybdate (ZnMoO4) nanosheets for electrochemical supercapacitor application

Abstract This study explores the synthesis and characterization of zinc molybdate (ZnMoO4) nanosheets with emphasis on their potential application for energy storage devices particularly supercapacitors. The synthesis of ZnMoO4 nanosheets was done through co-precipitation followed by examination of their structure, morphology, optical, thermal behaviour and electrochemical performance by various characterization techniques. X-ray diffraction (XRD) analysis confirmed that the formation of monoclinic ZnMoO4 phase with the average crystallite size 17.93 nm. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) revealed that this material had nanosheets-like structure which helps to increase ion transport and surface area; these two factors are essential for enhancing the material’s supercapacitor efficacy. The semiconductor characteristics were determined using UV–Visible diffuse reflectance spectroscopy (UV-DRS) which indicated a band gap energy of 4.2 eV. Fourier transform infrared (FTIR) analysis confirmed that the presence of Zn–O and Mo–O bonds in their crystal lattice. Thermogravimetric analysis (TGA) showed that the ZnMoO4 nanosheets had thermal stability since they experienced only a slight mass loss of 2.57 % up to 800 °C. Cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) tests were undertaken to find out the specific capacitance and the value is 618 F g⁻1 at a current density of 1 A g⁻1.

Synthesis and application of aluminum substituted ZnO nanowires on carbon fibers photocatalyst for the removal of methylene blue dye from aquatic mediums

In this research, pristine and aluminum substituted ZnO nanowires grown on carbon fibers synthesised by hydrothermal method. The effect of Al concentration on morphology, structure, optical properties and photocatalytic activity on methylene blue was investigated. The aluminum concentration values of 0.5 %, 1 %, 5 % and 10 % of Zn(NO3)2·6 H2O concentration were tested. Resulting structures were characterized by scanning electron microscopy, X-ray Diffraction, diffuse reflectance spectroscopy and UV-Vis diffuse reflectance spectroscopy. XRD results indicates that pristine and aluminum substituted ZnO nanowires has hexagonal zincite crystal structure. The changes of crystal size, crystal parameters, strain and stress with aluminum substitution were investigated. Increasing concentration of aluminum reduced the crystallinity of ZnO. A dramatic change was seen in crystallite size from 40.78 nm to 22.73 nm. Distortion is seen on crystal structure of substituted ZnO causing stress due to different ionic radii between Zn2+ and substituent ions. Tensile stress of 1.38 Pa is calculated for aluminum substituted ZnO nanowires. Smaller ionic radii of aluminum causes positive tensile stress. Optical band gap of structures was analysed. Al substitution reduces the band gap of ZnO NWs/CFs. DRS results shows that Al incorporation led to a 0.05 eV decrease in the bandgap of ZnO NWs/CFs structure. Photocatalytic activity of pristine and aluminum substituted ZnO nanowires on carbon fibers structures were tested on degradation of methylene blue (MB). Al substitution enhances the photocatalytic activity of ZnO nanowires coated on carbon fibers. 1 % Al substituted ZnO NWs on CFs demonstrated highest degradation efficiency with 0.9879 h−1 kinetic rate.

Visible light sensitive BiVO4–TiO2 nanocomposites for photocatalytic dye degradation

Abstract The hydrothermal approach was used to prepare visible light active BiVO4–TiO2 nanosheet composites in varying molar ratios. The photoluminescence (PL) spectrum, X-ray photoelectron spectroscopy (XPS), UV-Visible Diffuse Reflectance Spectroscopy (DRS), Transmission electroscopy (TEM), Brunauer-Emmett-Teller (BET) and field emission scanning electron microscopy (FESEM), were used to analyze the photocatalysts and composites. Photocatalytic activity of BiVO4–TiO2 composites was investigated by decolorizing methylene blue. Out of four different molar ratio BiVO4–TiO2 composites with a molar ratio of 3:1 BiVO4 TiO2 composite showed enhanced photocatalytic activity which is further proved by photoluminescence investigation of coumarin and Scavenger test. The DRS of BiVO4 TiO2 composite showed red shift in optical absorption. The enhanced photocatalytic activity is due to minimizing electron hole recombination by making composite with TiO2.

Different metal-doped NiO nanoparticles for sunlight-mediated degradation of low-density polyethylene microplastic films.

Due to the widespread use and incorrect handling of plastics, we need to find a practical and effective way to eliminate plastic waste from the environment. Different metal-doped nickel oxide (DMD-NiO) nanoparticles (NPs) were synthesized using a sol-gel technique and were used to degrade low-density polyethylene (LDPE) microplastic (MP) films when exposed to sunlight. The optical and structural properties of sol-gel method synthesized materials were investigated using a variety of characterization methods (Fourier transform infrared (FT-IR), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), X-ray diffractometer (XRD) analysis, X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, and thermogravimetric analysis (TGA). Degradation study results suggest that the photocatalytic activity of DMD-NiO-LDPE nanocomposites (NCs) films was greater than that of pure LDPE and undoped NiO-LDPE films. Because of their increased optical absorption and efficient suppression of photo-produced charge carriers' recombination, the DMD-NiO NPs showed higher photocatalytic degradation of LDPE films. Thus, LDPE films with 2% wt Fe-NiO (iron-doped nickel oxide) nanomaterials showed a degradation of around 38.16% among DMD-NiO-LDPE NCs films under visible light over a short period of 30 days (240 h). The formation of carbonyl groups in the degradation product of LDPE was confirmed by Fourier transform infrared (FT-IR) analysis. When compared to the original LDPE film, the Fe-NiO-LDPE NCs films showed a significant decrease in crystallinity and carbonyl indexes, as much as 8.4% lower. The current project proposes the development of eco-friendly photocatalysts using a sol-gel technique for combating MP pollution in the environment.

La-supported SnO2–CaO composite catalysts for efficient malachite green degradation under UV–vis light

This study presents the development and optimization of La@SnO2–CaO composite catalysts for efficient photocatalytic degradation of malachite green dye in aqueous solutions under UV–vis light irradiation. The catalysts were prepared via conventional incipient-wetness impregnation and thoroughly characterized using advanced analytical techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, UV–vis diffuse reflectance spectroscopy, N2 adsorption–desorption analysis, and scanning electron microscopy. To optimize photodegradation efficiency, the effects of three independent factors were systematically investigated using response surface methodology: Temperature, pH, and Sn/Ca molar ratio. Our results reveal optimal conditions for maximum dye degradation: pH 7, Sn/Ca molar ratio of 0.33, and a process time of 35 min, resulting in a maximum photodegradation efficiency of 98.80% for malachite green dye. Notably, visible light exhibited a more pronounced effect on dye degradation compared to UV light over time, with visible light achieving 25% greater dye removal after 60 min of illumination. Furthermore, the catalyst showed excellent recyclability, retaining 85% of its initial activity after five consecutive cycles. These findings contribute significantly to the development of sustainable methods for dye removal from wastewater and highlight the potential of La@SnO2–CaO composite catalysts in environmental remediation processes, particularly in treating textile industry effluents.

Phytomediated synthesis of WO3 nanoparticles using Solanum lycopersicum fruit extract for enhanced photocatalytic activity of 2,4-dichlorophenol.

In the present study, bio-citric acid/tungsten oxide (WO3) (BCAWO) nanoparticles (NPs) were prepared by using Solanum lycopersicum fruit extract as a reducing as well as a capping agent. The photocatalysts were characterized by UV-vis diffuse reflectance spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), high-resolution transmission electron microscopy, and photoluminescence spectroscopy techniques. Diffraction peaks in the XRD spectrum were identified as the crystal planes of crystalline tungsten oxide. The BCAWO had an average size of 23.14 nm. For W-O bonds, the Fourier transform infrared spectrum displays the vibrational peak at 671.23 cm-1. A prominent absorption band was observed at 268 nm, indicating the 1.2 eV bandgap. Under xenon (Xe) lamp irradiation, the synthesized BCAWO nanoparticles showed notable photocatalytic degradation of 2,4-dichlorophenol (2,4-DCP), with a degradation rate of 96%. With BCAWO concentrations of 2.5 g/L, pH of 4, reaction period of 180 min, and 2,4 DCP concentration of 10 mg/L, the degradation of 2,4-DCP had the highest efficacy, 96%. The degradation of phenols in wastewater may be facilitated by using the green WO3 nanoparticles as a photocatalyst, according to the results.

Isothermal conversion of methane to methanol over Cu-CHA using different oxidants

Methane oxidation to methanol in cyclic processes using CuO-zeolites has traditionally employed O2 and N2O as oxidants. This study explores the use of Cu-CHA zeolite, demonstrating that CO2 can substitute O2 in an isothermal reaction at 400 °C, analogous to previous findings using Cu-MAZ. The use of in situ UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS) and density functional theory (DFT) theoretical calculations identified the formation of a binuclear copper hydroxide complex, Z-[CuOH-HOCu]2+-Z, on the Cu-CHA. Initial treatment using CO2 led to marginally superior catalytic activity, compared to the use of O2 alone, indicating the stability of the Z-[CuOH-HOCu]2+-Z complex against self-reduction at 400 °C. In subsequent cycles, activation with O2 facilitated the oxidation of adsorbed methanol, yielding water and reconstituting the active sites. Conversely, activation with CO2 led to the partial desorption of methanol, precluding water production and subsequent catalyst regeneration. The findings suggested that both O2 and CO2 activations necessitated a post-reaction water extraction step, followed by thermal treatment to replenish the active sites. Importantly, the results indicated that CO2 could be used as a viable alternative oxidant to O2 in this catalytic process, potentially enhancing the sustainability of industrial methanol production.

La3+ doped ZnFe2O4 synthesized via green chemistry approach using Uncaria gambir Roxb: A study on structural, optical, magnetic, and photocatalytic properties

Lanthanum-doped zinc ferrite (ZFLa) nanoparticles were synthesized via a hydrothermal method, utilizing Uncaria gambir Roxb leaf extract as a capping and stabilizing agent. X-ray diffraction (XRD) and Le Bail refinement confirmed a cubic spinel structure formation with an Fd-3m space group. Fourier-transform infrared spectroscopy (FTIR) analysis indicated a shift of the vibration mode of the tetrahedral site to a higher frequency with increasing lanthanum concentration. Raman spectroscopy revealed an additional peak in the A1g mode at 605 cm−1 for ZnFe1.9La0.1O4 (ZFLa10), suggesting the formation of an inverse spinel structure due to a complex cation distribution at the tetrahedral sites. Scanning electron microscopy (SEM) showed that all samples exhibited spherical grains at the nanoscale, with particle size decreasing as lanthanum concentration increased. UV–Vis diffuse reflectance spectroscopy (DRS) indicated band gap energies within the visible light range (1.84 to 1.86 eV). Brunauer-Emmett-Teller (BET) analysis confirms the increased surface area and pore diameter due to the introduction of La3+ ions, the specific surface area and pore diameter were 96.76 m2/g and 8.78 nm for ZFLa0, and 106.21 m2/g and 10.49 nm for ZFLa10, respectively. The adsorption percentage increased from 17.59 % for ZFLa0 to 55.56 % for ZFLa10. Photocatalytic investigations demonstrated that all catalysts exhibited good activity in degrading Direct Red 81 dye, with ZFLa10 showing the highest photocatalytic activity under direct sunlight, achieving up to 99.68 % degradation of the dye. Stability tests demonstrated remarkable durability, with ZFLa10 maintaining 90.20 % degradation efficiency after five cycles, establishing it as an excellent photocatalyst candidate.

NH4Ca[B5O7(OH)4] H2O: A Biaxial Mixed‐Cation Pentaborate with Moderate Birefringence

AbstractAmmonium‐calcium mixed‐cation pentaborate NH4Ca[B5O7(OH)4]·H2O has been synthesized for the first time. Single‐crystal X‐ray diffraction analysis reveals that it crystallizes in the triclinic space group P‐1 with lattice parameters a = 6.7042(3) Å, b = 7.1859(3) Å, c = 10.7447(4) Å, α = 100.304(3), β = 97.774(3), γ = 96.972(3). The structure is characterized by 1D boron–oxygen chains composed of [B5O7(OH)4]3− polyanions that are further interspaced by Ca2+, NH4+ cations, along with lattice water molecules. The phase purity and thermal stability of the as‐synthesized sample were confirmed by XPRD and TG‐DSC analyses. Experimental UV–vis diffuse reflectance spectroscopy coupled with Urbach fitting indicates a direct bandgap of 4.50 eV, contrasting with theoretical calculations that suggest an indirect bandgap of 5.53 eV. Additionally, both theoretical computation and polarized light experimental test indicate that NH4Ca[B5O7(OH)4]·H2O exhibits moderate birefringence.

Visible Light Induced Photocatalytic Degradation of Diclofenac in Aqueous Solution Using Fabricated ZnO/g-C3N4 by Facile Calcination Technique.

The ability of the heterojunction between two distinct semiconductors with appropriately matched band gaps to improve the separation of photogenerated electron-hole pairs has been demonstrated to enhance photocatalytic activity. Hence, ZnO/g-C3N4 composites have been fabricated by the facile deposition and calcination of ZnO and g-C3N4. X-ray photoelectron spectroscopy, powder X-ray diffraction, and Fourier transform infrared spectroscopy confirm the formation of the composite. Scanning electron microscope, transmission electron microscope, and energy-dispersive X-ray spectroscopy morphological analysis reveal that ZnO was homogeneously spread over the g-C3N4 surface. UV-vis diffuse reflectance spectroscopy analysis shows the slightly enhanced visible light absorption ability of the composite. Photoluminescence (PL) spectroscopy and electrochemical impedance spectroscopy analysis prove the higher charge separation of the composite during the irradiation of light. The composite shows admirable photocatalytic efficiency in the visible light-driven photocatalytic degradation of an aqueous diclofenac (DFC) solution. The superoxide anion radical (•O2 -) and hydroxyl radical (•OH) act as reactive species during the degradation reaction. Probable reaction mechanisms have been proposed.

Facile one-pot synthesis of photoresponsive Cu1.8S and CuInS2 nanostructures aided by Cu-pyrimidylthiolate molecular precursor

Copper-based binary and ternary sulfides have attracted significant attention due to their excellent photo-physical properties, making them highly promising for high-performance energy harvesting and storage devices. This study focuses on the synthesis and structural characterization of an air-stable hexanuclear Cu-pyrimidylthiolate cluster complex which serves as an efficient single-source precursor for the preparation of Cu1.8S nanocrystals. Furthermore, coupling the molecular precursor with suitable indium source resulted in a facile one-pot pathway for the preparation of technologically important, copper-based ternary CuInS₂, nanocrystals. The crystal structure, phase purity, and compositions of the nanostructures were confirmed using PXRD, XPS, EDS, and area elemental mapping. Electron microscopic studies revealed the formation of polygonal and hexagonal morphology with varied size in Cu1.8S and CuInS₂ nanocrystals respectively. UV-Vis diffuse reflectance spectroscopy showed a slight blue shift in the band gap of the nanostructures compared to their bulk counterparts which can be attributed to quantum confinement or surface lattice distortion effects. The band gap of the pristine nanocrystals along with high photocurrent and stable photo-switching characteristics suggest that they can serve as suitable electrode material for optoelectronic and photodetector devices.

Physical and enhanced photocatalytic MO dye degradation behaviour of Zn doped β-Ga2O3 microrods

This work explored the effects of Zn doping on the structural, micrographic, optical and photocatalytic behaviour of gallium oxide (β-Ga2O3) microrods. The X-ray diffractogram (XRD) and Raman spectral analyses confirmed the monoclinic structure of β-Ga2O3, with a shift to lower angles in the XRD pattern indicating Zn incorporation into the Ga2O3 lattice. The Scanning electron microscopy (SEM) images revealed a rod-like shape, with the diameter decreasing from 604 nm to 573 nm with Zn doping. Further analysis using TEM, HR-TEM, SAED, EDX, and elemental mapping confirmed the shape, crystallinity, crystal structure, and elemental distribution. The interplanar spacings were measured as 0.4 and 0.2 nm, corresponding to the (002) and (−311) planes of β-Ga2O3. UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS) showed a slight shift in the absorption edge, while photoluminescence (PL) analysis demonstrated strong UV and weak visible light emission. Photocatalytic results revealed a high efficiency of dye degradation,(i.e) 98 % (20 ppm) and 89 % (30 ppm) against methyl orange (MO) dye aqueous solution over 150 min, with a rate constant of 0.02/min and 0.01/min, respectively for 1.5 wt% Zn doping. This suggests that the Zn-doped material holds promise as a photocatalyst for wastewater treatment applications.

Anodic Synthesis of Highly Ordered TiO2 Nanotube Arrays: Role of Electrolyte Composition on the Structural, Morphological, Optical, and Photo-electrochemical Properties

The fluoride species present in two different anodizing electrolytes were used to produce TiO2 nanotube arrays (TiO2 NTAs) by simultaneous anodic reaction and chemical dissolution. In this investigation, two different electrolytes were used for the preparation; [Eth-TiO2 NAs: 95 ml ethylene glycol+0.5% NH4F+5 ml DI water] and [Gly-TiO2 NAs: 75 ml glycerine+0.5% NH4F+25 ml DI water]. The effects of the prepared electrolytes used in the synthesis of TiO2 nanotube arrays on structural element composition, morphology, and optical properties are the focus of this study and are characterized by X-ray diffraction (XRD), scanning electron microscopy field emission (FE-SEM), energy-dispersive X-ray spectroscopy (EDX) and UV-vis diffusion reflection spectroscopy (DRS), respectively. The photoelectrochemical properties of TiO2 NTAs prepared in different electrolytes were investigated. The photoelectrochemical performance of TiO2 NTAs in Na2SO3 (0.1 M) and Na2S (0.1) was examined under the light of 100 mW/cm2 from a xenon lamp. Comparing the photoelectrochemical (PEC) results of both electrolytes, we find that Eth-TiO2 NTAs contribute a wide surface area resulting in an enhanced PEC response. TiO2 NTs, which were prepared with Eth-TiO2 NTAs, exhibited the highest photocurrent density, 0.326 mA cm–2, and photoconversion efficiency (0.22%).

Competent CuS QDs@Fe MIL101 heterojunction for Sunlight-driven degradation of pharmaceutical contaminants from wastewater

In this study, we introduce an advanced photocatalyst developed by integrating copper sulfide quantum dots (CuS QDs) with an iron-based metal–organic framework (MOF), specifically Fe MIL101. The resulting CuS QDs@Fe MIL101 photocatalyst is engineered to efficiently degrade meloxicam (MLX) under simulated sunlight. The heterojunctions were generated by incorporating different concentrations of CuS QDs (5 %, 10 %, 15 %, 20 %, and 50 %) into the Fe MIL101 MOF matrix using the microwave-assisted hydrothermal method. The results of the XRD and the TEM studies confirmed the formation of the heterojunctions, which maintain the structural integrity of both CuS QDs and Fe MIL101. The BET measurements indicated a decrease in surface area upon CuS QDs incorporation, attributed to porés blockage and structural modifications. UV–Vis diffuse reflectance spectroscopy (DRS) revealed a redshift in absorption edges as CuS QDs content increased, enhancing visible light absorption. Photoluminescence (PL) investigations revealed that the 15 % CuS QDs@Fe MIL101 heterojunction had an effective charge separation and low recombination rates. The zeta potential analysis revealed a negative surface charge, indicating an overall electronegative characteristic. The photocatalytic performance, assessed through the degradation of MLX, demonstrated that the 15 % CuS QDs@Fe MIL101 heterojunction achieved the maximum degradation efficiency, reaching 96 % after 45 min of irradiation at a dosage of 0.1 g/L. This exceptional performance is attributed to potent charge separation, improving visible light absorption, high surface area and adsorption capacity. Various scavengers were used to investigate the roles of different reactive species, revealing holes as the predominant active species in the photocatalytic degradation process. These results highlight the potential of 15 % CuS QDs@Fe MIL101 heterojunctions as efficient photocatalyst for environmental remediation from pharmaceutical pollutants under simulated sunlight. These findings highlight the potential for application of CuS QDs@Fe MIL101 in real-world wastewater treatment systems, particularly in addressing pharmaceutical contaminants like meloxicam in industrial effluents.

Zeolitic imidazolate framework-67/barium zirconate titanate nanocomposite, Part I: Synthesis, characterization, and boosted photocatalytic activity

Using BaTi0.85Zr0.15O3/ZIF-67 (BTZ/ZIF-67) nanocomposite, tetracycline (TC) was photodegraded. Characterization of the samples was carried out using a variety of techniques, including XRD, FESEM-EDS (Field Emission Scanning Electron Microscopy – Energy Dispersive X-ray Spectroscopy), FT-IR (Fourier Transform Infra-Red), TEM (Transmission Electron Microscopy), BET (Brunauer-Emmett-Teller), BJH (Barrett-Joyner-Halenda), PL (Photoluminescence), TG-DTG (Thermogravimetry and Derivative Thermogravimetry), and UV–Vis DRS (Diffuse Reflectance Spectroscopy). BTZ/ZIF-67 nano-composites were synthesized using a one-step co-precipitation method. BTZ (30 %wt)/ZIF-67 showed the most impressive photocatalytic ability among the binary photocatalysts. Averaging the crystallite sizes of the nanocomposite samples identified by Scherrer and Williamson-Hall methods was 43.3 nm and 65.0 nm, respectively. The pHpzc values of samples of BTZ and BTZ (30 %wt)/ZIF-67 were approximately 6.7 and 10.0, respectively. Using the proposed method, we measured 357, 414, and 377 nm absorption edges for ZIF-67, BTZ, and BTZ (30 %wt)/ZIF-67 samples, which correspond to 3.47, 2.99, and 3.28 eV bandgap energies, respectively. The specific surface areas of BTZ, ZIF-67, and BTZ (30 %wt)/ZIF-67 nanocomposite are 122.15, 1218, and 1509 m2g−1, respectively. Under optimum conditions (0.8 g/L of the catalyst, CTC: 30 mg/L, and a pH 5), 89.5 % of total organic carbon (TOC) was removed within 180 min. Compared to BTZ photocatalyst, the BTZ (30 %wt)/ZIF-67 nanocomposite has a significantly larger surface area, thus enhancing photocatalytic activity. A synergistic effect was observed in the photodegradation of TC under Hg-lamp irradiation with the proposed BTZ/ZIF-67 composite. It is possible to alter the photocatalytic activity of the catalyst by changing the BTZ (30 %wt)/ZIF-67 ratio.

Enhanced band gap energy of one-pot mechano-synthesized Ag3PO4 for Orange G photodegradation under visible light irradiation: An in-depth experimental and DFT studies

The present study highlights the efficiency of Ag3PO4 photocatalyst with a band gap of 2.25 eV, synthesized by a green and one-pot simple mechanochemical method, towards photodegradation of orange G under visible irradiation. The phase structure, morphology, and optical properties of mechano-synthesized Ag3PO4 were investigated using X-ray diffraction, Scanning Electron Microscopy, Thermogravimetric Analysis, Fourier Transform Infrared, the Brunauer-Emmet-Teller surface area, and UV–vis diffuse reflectance spectroscopy. DFT calculations were also conducted for band gap energy prediction. The photocatalytic activity of the sample was evaluated using a central composite design for surface response methodology (CCD-RSM) to determine the optimal conditions for Orange G (OG) removal. The photocatalytic activity of Ag3PO4 was approximately 93 % within 20 min of reaction under irradiation for 24.6 mg/L and 11 mg/L of Ag3PO4 and Orange G, respectively. Trapping experiments confirmed that peroxides and hydroxyl radicals are the dominant active species in the photodegradation process.