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Using citric acid as a chelating agent, BiFeO3 nanopowders doped with La at the A-site, Mn at the B-site, and codoped with La/Mn were synthesized through an ultrasonic-assisted sol-gel method. Characterization techniques such as X-ray diffraction (XRD), ultraviolet visible diffuse reflectance spectroscopy (UV-DRS), X-ray photoelectron spectroscopy (XPS), specific surface area and pore size analysis (BET), and photoluminescence spectroscopy (PL) were employed to analyze the morphology, structure and elemental composition of Bi1 - x Lax Fe1 - y Mny O3 crystals. The results indicate that doping with La and Mn elements can significantly alter the crystal structure and morphology of BiFeO3, suppressing the recombination of its charge carriers. Using Bi1 - x Lax Fe1 - y Mny O3 as a photocatalyst, the effects of pH value and light source on the photocatalytic degradation of simulated pollutants were investigated, and further experiments to explore the photocatalytic mechanism were conducted. The results reveal that La/Mn co-doped samples show significant differences in degradation rates for congo red (CR) and methylene blue (MB), which is related to the electronegativity of the dye molecules. Meanwhile, doping enhances the magnetic properties of the samples, which is beneficial for recycling and improving its utilization efficiency. [ABSTRACT FROM AUTHOR]

Pure ZnO nanoparticles and ZnO-Al2O3 nanocomposites prepared with Al2O3 content of 10, 20 and 30 atomic ratios were synthetized via Sol–gel method and then calcined for 2 h at different temperature 450, 700 and 900 °C. The structural, morphological and optical properties of the powder as-synthetized are investigated. Photocatalytic activity was assessed using methylene blue degradation. In the present work, the high purity of the nanoparticles was confirmed by EDS spectra. The XRD results show that ZnO powder has a wurtzite structure. The aluminum in composite powders leads to the appearance of the ZnAl2O4 spinel phase and it shows that this phase is appeared in the ZnO-30% at Al (Z30A) nanocomposite from an annealing temperature 450 °C as well as increasing the annealing temperature reduces the crystallite size. The flower-like morphology was well defined in these nanocomposites with an average size in the nanometer range. Photoluminescence reveals the incorporation of aluminum into the as-synthetized nanocomposites compared with XRD results.The optical absorption spectra have been presented the relationship between the band gap, particle size, annealing temperature, Al concentration and Urbach energy. Our result suggests that the annealing temperature 700 °C can be considered as an order-disorder transition temperature. The photo-catalytic application of pure ZnO and their composites nanoparticles shows that the best photocatalytic activity is obtained for the Z30A nanocomposite in the presence of MB dye, under UV light. This sample has the smallest crystal size and a high content of the ZnAl2O4 phase. A small particle size ensures high photoactivity. Highlights: We synthesized pure ZnO and ZnO-Al2O3 nanoparticles using the sol–gel method due to its simplicity. The emergence of the ZnAl2O4 spinel phase in ZnO-Al2O3 nanocomposites results from heat treatment and aluminum content. ZnO-30% Al2O3 nanocomposites, containing a high proportion of the spinel phase, demonstrate the best structural, optical, and morphological properties, leading to enhanced photocatalytic activity. [ABSTRACT FROM AUTHOR]

Abstract MgFe2O4@ZnAl2O4 magnetic nanocomposites were synthesized with the easy and green sol–gel method, and their photocatalytic efficiency was followed toward degradation of reactive blue 222 (RB222) dye under visible light irradiation. Prepared nanocomposites were fully characterized. The SEM and TEM images revealed the spherical morphology of the produced nanocomposites, with average size of 20–25 nm. The XRD pattern of sample exhibited the successful synthesis of the MgFe2O4@ZnAl2O4 MNCs with crystallite size 13 nm. The saturation magnetization (Ms) of the nanocomposites was examined using VSM, indicating a value of 6.59 emu/g. The absence of Hc and Mr values confirms the superparamagnetic nature of the nanoparticles. In addition, the surface area was calculated to be 78.109 m2/g utilizing BET analysis, and the band gap was determined to be 1.88 eV by DRS analysis. The photocatalytic, photolysis, and adsorption performance were investigated and result shown photodegradation activity was higher than others. These results confirm the synergetic effect between the MgFe2O4@ZnAl2O4 MNCs and visible light irradiation to degradation of organic dye. The results indicate that rapid degradation of 96% of RB222 dye occurred in just 10 min, with a TOC removal rate of approximately 59%. Furthermore, radical scavenger agents also clarified photodegradation of RB222 dye.

In this research work, pure and lanthanum (La)-doped copper oxide nanoparticle (CuO-NPs) are synthesized using a sol-gel technique which is quite simple, efficient and cost-effective as well. Various characterization techniques have been employed to investigate the effect of rare earth dopant (La) on morphological, compositional, structural, optical, and vibrational properties of fabricated nanomaterial which is tested as potential photo catalyst. Quite interestingly, the bandgap was reduced by the introduction of dopant element. Additionally, the average particle size was also reduced for doped samples. Degradation of methylene blue (MB) was investigated under UV visible light for 100 min in the presence of synthesized photocatalysts. The best efficiency of 80% is achieved by 2% La-doped sample attributed to Burstein-Moss effect. Experimental results are well consistent with the results of the simulation which were realized while using finite element analysis (FEA) technique in RF module (version 5.3a) of COMSOL Multiphysics. This simulation technique helped to understand the insight about the various aspect of the photocatalytic process reported here. [ABSTRACT FROM AUTHOR]

MgFe2O4@ZnAl2O4 magnetic nanocomposites were synthesized with the easy and green sol–gel method, and their photocatalytic efficiency was followed toward degradation of reactive blue 222 (RB222) dye under visible light irradiation. Prepared nanocomposites were fully characterized. The SEM and TEM images revealed the spherical morphology of the produced nanocomposites, with average size of 20–25 nm. The XRD pattern of sample exhibited the successful synthesis of the MgFe2O4@ZnAl2O4 MNCs with crystallite size 13 nm. The saturation magnetization (Ms) of the nanocomposites was examined using VSM, indicating a value of 6.59 emu/g. The absence of Hc and Mr values confirms the superparamagnetic nature of the nanoparticles. In addition, the surface area was calculated to be 78.109 m2/g utilizing BET analysis, and the band gap was determined to be 1.88 eV by DRS analysis. The photocatalytic, photolysis, and adsorption performance were investigated and result shown photodegradation activity was higher than others. These results confirm the synergetic effect between the MgFe2O4@ZnAl2O4 MNCs and visible light irradiation to degradation of organic dye. The results indicate that rapid degradation of 96% of RB222 dye occurred in just 10 min, with a TOC removal rate of approximately 59%. Furthermore, radical scavenger agents also clarified photodegradation of RB222 dye. [ABSTRACT FROM AUTHOR]

In this article, the erbium nitrate pentahydrate (Er(NO3)3·5H2O), tetrabutyl titanate (C16H36O4Ti), glacial acetic acid (CH3COOH), and anhydrous ethanol (C2H5OH) were used as the main raw materials. The Er2Ti2O7 was successfully prepared by the sol-gel method. The structure and morphology of the samples were characterized by thermogravimetric-differential thermal analyzer (TG-DSC), X-ray diffractometer (XRD), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FT-IR). The 10 mg/L methyl orange solution was used as a simulated pollutant under UV light conditions. The effects of different temperatures and light times on the photocatalytic performance of the Er2Ti2O7 samples were investigated. The results showed that the pure Er2Ti2O7 samples could be successfully prepared by calcination in the temperature range of 750–1000 °C. The average grain size of Er2Ti2O7 was about 20–60 μm, and the photocatalytic performance of Er2Ti2O7 samples calcined at 900 °C was the best. When the illumination time is 90 min, the degradation rate of methyl orange reaches to about 100%. The preparation of Er2Ti2O7 by the sol-gel method is a kind of ultraviolet light photocatalyst with wide application prospects. [ABSTRACT FROM AUTHOR]

Using citric acid (C6H8O7·H2O), thulium oxide (Tm2O3), nitric acid (HNO3), tetrabutyl titanate (C16H36O4Ti) as main raw materials, the Tm2Ti2O7 samples were successfully prepared by sol-gel method. The prepared samples were characterized by the thermogravimetry and differential scanning calorimetry (TG-DSC), X-ray diffractometer (XRD), scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR). Using 50 mg/L azo dye methyl orange solution as the simulated sewage, the photocatalytic activity of Tm2Ti2O7 samples was investigated at different calcination temperatures and illumination times. The experimental results show that pure Tm2Ti2O7 samples can be prepared at a calcination temperature of 750–1000 °C. According to SEM analysis, Tm2Ti2O7 samples is irregular, with an average particle size of approximately 10 μm. The degradation rate of methyl orange of each sample calcined at 750–1000 °C temperature range can reach more than 50% when exposed to ultraviolet light for 30 min, and the sample calcined at 900 °C has the best photocatalytic effect. When it degrades 50 mg/L methyl orange for 90 min, the degradation rate can almost reach 100%, and the degradation kinetic constant is 0.0488 min−1, which conforms to the first-order kinetics. The above conclusions indicate that Tm2Ti2O7 is a novel photocatalyst with broad application prospects in the field of ultraviolet photocatalysis. [ABSTRACT FROM AUTHOR]

Using citric acid (C6H8O7·H2O), ethylene glycol (C2H6O2), Yttrium(III) nitrate (Y(NO3)3·6H2O) and Copper(II) nitrate (Cu(NO3)2·3H2O) as main raw materials, the Cu2Y2O5 samples were successfully prepared by sol-gel method.The samples were characterized by thermogravimetry differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR). Using azo dye methyl orange solution as raw material to simulate wastewater, the photocatalytic activity of Cu2Y2O5 samples was investigated under different synthesis temperatures and light conditions. The experimental results show that pure Cu2Y2O5 samples can be prepared at a calcination temperature of 750 °C to 1000 °C, with Cu2Y2O5 samples prepared at 800 °C having the best photocatalytic activity, with an average grain size of 0.5-1 μm. Under the UV light condition, when the light time is 45 min, the initial concentration of methyl orange is 100 mg/L, the degradation rate of Cu2Y2O5 sample prepared at 800 °C to methyl orange reaches about 100%. Cu2Y2O5 is a catalyst with excellent photocatalytic performance and broad application prospects. [ABSTRACT FROM AUTHOR]

This investigation entailed the synthesis of Fe3O4/SiO2/TiO2 via the sol-gel technique, and the Fe3O4/SiO2/TiO2/Cu nanocomposite utilizing Cu(NO3)2.3H2O through the photodeposition approach. Subsequent to synthesis, these specimens underwent comprehensive characterization employing an array of analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray microanalysis (EDS), vibrating sample magnetometry (VSM), Diffuse Reflectance Spectroscopy (DRS) and Fourier transform infrared (FT-IR) spectroscopy. The focal point of this study was the assessment of the catalytic proficiency of both Fe3O4/SiO2/TiO2 and Fe3O4/SiO2/TiO2/Cu magnetically responsive nanocatalysts in facilitating the degradation of Reactive Methylene Blue (MB) under ultraviolet irradiation at ambient temperature. A notable attribute of these magnetic nanocomposites is their capacity for complete recovery, enabled by the application of an external magnetic field, thereby demonstrating significant potential for practical applications in environmental remediation. Highlights: A combination of sol-gel and photodeposition method was developed for the fabrication of Fe3O4/SiO2/TiO2/Cu nanocomposites, showcasing a breakthrough in materials science for water treatment technologies. The study demonstrates a significant improvement in the degradation of methylene blue dye under UV light, marking a pivotal advancement in the effectiveness of water purification methods. The easy magnetic recovery feature of the nanocomposites was highlighted, enabling their efficient reuse and contributing to waste reduction in water treatment processes. The research unveils the synergistic effects between TiO2 and Cu, enhancing photocatalytic activity and leading to faster degradation rates, which underscores the importance of component interaction in nanocomposites. The potential of these nanocomposites to address environmental pollution was emphasized, offering a novel, reusable, and efficient solution for water purification, highlighting the article's contribution to sustainable environmental management. [ABSTRACT FROM AUTHOR]

BACKGROUND: Semiconductor photocatalysts based on TiO2 nanoparticles were synthesized via the sol–gel method and subsequently modified using monometallic (Bi‐TiO2, Zn‐TiO2) and bimetallic (Bi/Zn‐TiO2) doping through the wet‐impregnation technique. The prepared photocatalysts underwent comprehensive characterization using X‐ray diffraction analysis, Fourier transform infrared spectroscopy, ultraviolet–visible diffuse‐reflectance spectroscopy, field emission scanning electron microscopy, photoluminescence, and thermal gravimetric analysis. The photocatalytic performance of these well‐characterized photocatalysts was assessed for the degradation of the model organic pollutant, nitrobenzene. RESULTS: Among the various doped TiO2 catalysts, Bi/Zn co‐doping at a ratio of 0.25:0.75 (w/w) exhibited the most remarkable synergistic effect, achieving approximately 82% degradation of a 50 ppm nitrobenzene solution within just 90 min of reaction time under ultraviolet light irradiation. The rate constant for this process was determined to be 1.79 × 10−2 min−1, suggesting a pseudo‐first‐order kinetics model. CONCLUSION: The successful co‐doping of Bi and Zn metals to TiO2 resulted in improved photocatalytic performance. The enhanced performance could be attributed to the improved charge transfer facilitated by the synergistic effect among doped metals and TiO2. This finding highlights the significance of bimetallic doping and its potential applications in improving the photocatalytic efficiency of TiO2 nanoparticles for environmental remediation. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Non-biodegradable effluents form dying industries cause harm to environment. Usage of nanomaterials is an effective method for purification of such effluents. Agglomeration of photoactive nanomaterials can be reduced by doping with suitable coupling agents. The present study explores usage of Polyethylene glycol 4000 and Methyltrimethoxysilane as surface modifiers to Zinc oxide by sol–gel method. Structural analysis revealed hexagonal wurtzite phase of synthesized ZnO nanomaterial. Diffraction peaks had no major shift in position denoting crystallinity and purity. Presence of nano-sized particles was confirmed by FESEM analysis. Investigation of optical band bap energy of ZnO, ZnO/PEG-4000 and ZnO/PEG-4000/MTMS was made. Antibacterial efficacy analysis showed, all combinations of ZnO were sensitive against Staphylococcus aureus, Bacillus cereus, Escherichia coli and Pseudomonas aeruginosa. Photocatalytic degradation analysis revealed ZnO functionalized by both polymer and silane exhibited highest degradation efficiency under visible light source for MB dye, the efficiency was maintained even after five cyclic degradations.

In this study, complex BiMn2O5 (BMO) nanoparticles, well known for their applications in photocatalysts, magnetoelectric sensors, actuators, non-volatile information storages, and electrochemical supercapacitors, were synthesized through novel ultrasonication assisted sol–gel synthesis route. The corresponding Rietveld refinement confirms the monophasic nature of composition in Pbam space-group symmetry with orthorhombic structure. The morphological study examines the average grain size determined to be approximately around ∼ 64.50 nm, whereas, EDAX gives the elemental analysis. The vibrational modes of Mn–O and presence of other functional groups have been explored. The coexistence of the multivalency in Mn4+ and Mn3+ valence states, which are associated with the chemical stoichiometry of the synthesized compound is confirmed. The optimization of energy band-gap was attributed to influence the disordered crystal lattice and oxygen vacancies. The interesting Photoluminescence response of BiMn2O5 NPs in visible region indicates strong purple-blue emission under excitation wavelength λex ~ 370 nm and CIE parameters. BMO nanoparticles have been evaluated as a photocatalyst for the decomposition of Rhodamine B dye under visible light illumination because of their low bandgap. In contrast, the presence of smaller nanoparticles and uncompensated spins depict M-H plot shows no saturation at high magnetic field, which manifest non-ferromagnetic correlation. The thermomagnetic study in field-cooled/zero-field-cooled modes also indicates an antiferromagnetic Neel transition at around 41 K. The results obtained from measurements and associated properties of nanoparticles give an insight of BiMn2O5 nanoparticles for possible applications. [ABSTRACT FROM AUTHOR]

This work reports on the photocatalytic activity of tin oxide (SnO2)-doped magnesium (Mg) and fluorine (F) nanoparticles for methyl orange and safranin dye degradation under sunlight irradiation. Nanocatalysis-induced dye degradation was examined using UV–visible spectroscopy and a pseudo-first-order kinetics model. The results indicate that the prepared nanoparticles exhibit superior photocatalytic activity, and the degradation of methyl orange (MO) dye is approximately 82%. In contrast, the degradation of safranin dye is 96% in the same time interval of 105 min. The calculated crystallite size of the SnO2–Mg–F nanocomposite is 29.5 nm, which respects the particle size found in the DLS analysis with a tetragonal structure and spherical morphology affirmed. The optical characteristics were assessed, and their respective bandgap energies were determined to be 3.6 eV. The influence of F in Mg and SnO2 is recognized with the XRD and FT-IR spectra of the prepared particles. [ABSTRACT FROM AUTHOR]

Worldwide population growth and pollution have limited the availability of clean water. Therefore, it is imperative to develop rapid water purification techniques that can eliminate all primary water pollutants, such as organic compounds and synthetic dyes. Pollutant disposal using a photocatalytic technique is efficient and safe for the environment. In this context, the ZnO/MgFe2O4 heterostructure photocatalyst is produced via a sol–gel technique to degrade methylene blue (MB) as a benchmark dye. Synthesized samples are characterized by numerous analytical techniques, including X-ray diffraction analysis, scanning electron microscopy, scanning tunneling electron microscopy, vibrating sample magnetometer, Fourier transform infrared spectroscopy, I-V characteristics curves, and photoluminescence spectroscopy. Photocatalytic degradation efficiency is witnessed at 40.01%, 55.05%, and 71.02% for ZnO, MgFe2O4, and ZnO/MgFe2O4, respectively. Among all the samples, composite heterojunction demonstrates the highest photocatalytic degradation efficiency. The obtained results reveal that the presence of magnetic ferrite in heterojunction promotes the absorption of radiation, reduces electron–hole recombination, and improves charge transfer. High stability over multiple cycles and easy removal character are the added benefits of the tested heterojunction photocatalyst. [ABSTRACT FROM AUTHOR]

Using praseodymium nitrate, cobalt acetate and citric acid as main raw materials, the PrCoO3 photocatalyst was prepared by sol-gel method. The PrCoO3 samples were characterized by thermogravimetry and differential scanning calorimetry (TG-DSC), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR). The photocatalytic activity of PrCoO3 was tested by simulating polluted water with 10 mg/L methyl orange solution under ultraviolet light irradiation. The results show that pure PrCoO3 can be prepared by calcination in the range of 600 to 900 °C. The average particle size of PrCoO3 is about 30 μm. The photocatalytic performance of PrCoO3 is the best under the conditions of 700 °C calcination and ultraviolet light irradiation for 120 min, and the degradation rate of methyl orange (10 mg/L) can reach 98%. The PrCoO3 samples are consistent with first-order kinetics for the degradation of methyl orange. And the apparent rate constants is k = 0.0346 min−1. PrCoO3 sample shows good ultraviolet light photocatalytic activity and has a broad application prospect in the field of photocatalysis. [ABSTRACT FROM AUTHOR]

Mercury lamp, xenon lamp and ultraviolet lamp are widely used for photocatalytic treatment of water pollution and research. In order to reduce the use of high energy sources, an iron-doped nano-titanium dioxide photocatalyte which can respond under low-consumption LED lamp was prepared by sol-gel method. The physical phase composition, microscopic morphological structure and optical absorption properties in UV and IR were analyzed. The effects of Fe doping amount, initial concentration of solution and initial pH on the photocatalytic degradation of simulated wastewater rhoda mine B solution were investigated under LED white light irradiation conditions, and the degradation mechanism was analyzed. The results show that the doping of Fe3+ accelerates the phase transition from anatase to rutile in TiO2. Under the scanning electron microscope, the nanoparticles are well distributed and the agglomeration is not obvious. Doping of Fe3+ decreases the band gap width of TiO2 and makes the optical absorption edge red-shift, which decreases significantly from 3.2 eV to 2.7 eV. However, when the amount of Fe3+ doped is too high, the optical absorption edge of nano-Fe-TiO2 shifts blue and its activity in the visible region decreases significantly. Comprehensive analysis shows that the removal rate of Rhoda mine B is 89% when irradiated by LED white light（100W） for 72 hours at molar ratio n（Fe）:n（Ti）=0.3% and pH=7. It provides reference for catalytic degradation of organic pollutants by low energy consumption LED lamp [ABSTRACT FROM AUTHOR]

Using lanthanum nitrate, butyl titanate and citric acid as the main raw materials, lanthanum titanate (La2Ti2O7) was successfully prepared by sol-gel method. The samples were characterized by thermogravimetric differential thermal analysis (TG-DTA), X-ray diffractometry (XRD), scanning electron microscopy (SEM) and Fourier infrared spectroscopy (FT-IR). Using 10 mg/L azo dye methyl orange solution as simulated sewage, the photocatalytic activity of La2Ti2O7 was studied by changing the synthesis temperature and light time under ultraviolet light. The results show that pure La2Ti2O7 samples can be obtained at 600 °C∼900 °C. SEM showed that La2Ti2O7 was dominated by irregular particles, and the average grain size was 4 ∼ 6μm. The La2Ti2O7 samples are consistent with approximation zero order kinetic for the degradation of methyl orange. The photocatalytic results showed that the photocatalytic activity of La2Ti2O7 prepared by calcination at 800 °C and 900 °C for methyl orange solution was significantly better than that of other temperature sections. The photocatalytic activity of La2Ti2O7 calcined at 900 °C was the best, and the degradation rate of methyl orange reached about 95% for degradation 60 min. This indicates that La2Ti2O7 is a novel photocatalyst with wide application prospects in the field of UV photocatalysis. [ABSTRACT FROM AUTHOR]

Micropollutants (MPs) are widely occurring in surface water all over the world with extremely low concentrations, and their treatment requires high energy consumption and efficiency. In this study, a large-sized planar photocatalytic reactive ceramic membrane (PRCM) was prepared using the facile dip-coating method with nitrogen-doped TiO2 (N-TiO2-CM) for the purification of tetracycline hydrochloride (TC) as a model MP. The N-TiO2 nanoparticles and the as-prepared N-TiO2-CM were characterized by SEM/EDS, TEM, XPS, UV–Vis DRS, and FT-IR. A fixed bed reactor integrated N-TiO2-CM, and visible LED light was fabricated for the new PRCM water treatment system for the removal of TC with a comprehensive consideration of the degradation rate and permeate flux. The SEM/EDS results indicated that the N-TiO2 was uniformly and tightly loaded onto the flat CM, and the pure water flux could reach over 2000 L/(m2 × h) under a trans-membrane pressure (TMP) of −92 kPa. The fixed bed PRCM water treatment system is extremely suited for MP purification, and the removal efficiency of TC was as high as 92% with 270 min even though its initial concentration was as low as 20 mg/L. The degradation rate and permeate flux of N-TiO2-CM was 2.57 and 2.30 times as high as that of the CM, indicating its good self-cleaning characteristics. The quenching experiments illustrated that the reactive radicals involved in the PRCM process, •OH and •O2−, were responsible for TC degradation. This research also provides a utilization proposal for a scale-up N-TiO2-CM system for water and wastewater treatment. [ABSTRACT FROM AUTHOR]

Heterogeneous photocatalysis has been considered one of the most effective and efficient techniques to remove organic contaminants from wastewater. The present work was designed to examine the photocatalytic performance of metal (Cu and Ni) doped ZnO nanocomposites in methyl orange (MO) dye degradation under UV light illumination. The wurtzite hexagonal structure was observed for both undoped/doped ZnO and a crystalline size ranging between 8.84 ± 0.71 to 12.91 ± 0.84 nm by X-ray diffraction (XRD) analysis. The scanning electron microscope (SEM) and energy dispersive X-ray (EDX) revealed the irregular spherical shape with particle diameter (34.43 ± 6.03 to 26.43 ± 4.14 nm) and ensured the purity of the individual elemental composition respectively. The chemical bonds (O–H group) and binding energy (1021.8 eV) were identified by Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) results respectively. The bandgap energy was decreased from 3.44 to 3.16 eV when Ni dopant was added to the ZnO lattice. The comparative photocatalytic activity was observed in undoped and doped nanocomposites and found to be 76.31%, 81.95%, 89.30%, and 83.39% for ZnO, Cu/ZnO, Ni/ZnO, and Cu/Ni/ZnO photocatalysts, respectively, for a particular dose (0.210 g) and dye concentration (10 mg L−1) after 180 min illumination of UV light. The photocatalytic performance was increased up to 94.40% with the increase of pH (12.0) whereas reduced (35.12%) with an increase in initial dye concentration (40 mg L−1) using Ni/ZnO nanocomposite. The Ni/ZnO nanocomposite showed excellent reusability and was found 81% after four consecutive cycles. The best-fitted reaction kinetics was followed by pseudo-first-order and found reaction rate constant (0.0117 min−1) using Ni/ZnO nanocomposite. The enhanced photodegradation efficiency was observed due to decreases in bandgap energy and the crystalline size of the photocatalyst. Therefore, Ni/ZnO nanocomposite could be used as an emerging photocatalyst to degrade bio-persistent organic dye compounds from textile wastewater.

This paper presents the effect of fumed silica modification and calcination temperature on the physicochemical properties of photocatalysts and their activity under the UV-VIS and VIS light range. The materials were obtained by hydrolysis of titanium tetraisopropoxide (TTIP) combined with a calcination step. The obtained nanomaterials were characterized using analytical methods such as X-ray diffraction XRD, FT-IR/DRS infrared spectroscopy, UV-Vis/DRS spectroscopy and SEM scanning electron microscopy. BET specific surface area and zeta potential were also measured. It was observed that SiO2 modification inhibited the transformation phase of anatase to rutile and the increase in crystallite size during calcination. The calcination process contributed to a change in the surface character of photocatalysts under study from positively to negatively charged. The photocatalytic activity of samples was identified by determining the methylene blue decomposition under UV-VIS and VIS light. Experimental results showed that the addition of SiO2 and the calcination process increased the photoactivity. The obtained materials showed higher activity compared to the reference samples. It was found that the degree of dye removal increased along with increased calcination temperature. The highest activity was observed for photocatalyst SiO2(11.1%)/TiO2_600. [ABSTRACT FROM AUTHOR]

A comparative thermal analysis study was realized by the thermogravimetric and thermodifferential analysis (TG/DTG/DTA) and differential scanning calorimetry (DSC) on TiO2 system. This study is to establish the influence of the preparation method on thermal behavior of powders obtained by different methods as follows: the sol–gel (SG), microwave-assisted sol–gel (MW) and hydrothermal (HT) methods. Titanium (IV) ethoxide, titanium (IV) isopropoxide and titanium (IV) butoxide were used as TiO2 precursors, as well as the parental alcohol as solvent, and the hydrolyzing agent (ammonia containing water) was added drop by drop to obtain a solution with pH 10. Based on TG/DTG/DTA results, the temperature of 450 °C was chosen for the processing of powders in air. Morphology and structure of the calcinated powders were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The SEM images show spherical nano-sized particles and X-ray diffractograms for all samples calcinated at 450 °C show crystallization in a single phase of TiO2 (anatase). According to the activation energy, Ea, values calculated by Kissinger and Ozawa methods, amorphous-to-anatase transition is facilitated in the microwaved-assisted samples in comparison with the sol–gel derived samples. The photocatalytic activity of the TiO2 samples toward the degradation of methyl orange (MO) was evaluated, the sample denoted Ti-Bu-SG being the most effective removing a total of ~99% of the dye in 180 min, while Ti-Bu-MW presented the lowest degradation efficiency, about 82%. [ABSTRACT FROM AUTHOR]

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• Rare earth (RE) elements (Sm, Y, La and Ce)-Doped TiO 2 powder is prepared by the sol-gel spin-coating method. • RE doped TiO 2 powder inhibited the formation of rutile phase and the grain growth of TiO 2 powder. • The degradation efficiency of the TiO 2 powder for methylene blue was significantly improved by RE-doping. In the present work, pure and 1 mol% samarium (Sm), yttrium(Y), lanthanum (La), cerium (Ce)-doped titanium dioxide (TiO 2) powders were prepared by sol-gel method. Taking Methylene blue (MB) dye as degradation targets the photodegradation performance of the photocatalysts was studied. XRD spectra confirmed that the doping of rare earth elements (RE) could inhibit the transformation of TiO 2 from anatase to rutile crystal at high temperature of 800 °C. XPS analyzed the chemical state of the elements in the powder. Characterization such as SEM and TEM found that the doping of the RE elements made the severely agglomerated particles become dispersed and refined, increased the specific surface area, and reduced the optical bandgap. Simulated visible light degradation results of MB showed that the degradation efficiency was significantly improved by doping of the RE elements, and the best efficiency is 88 % for Sm-doped TiO 2 powder samples. [ABSTRACT FROM AUTHOR]

BiVO 4 has garnered significant interest as a semiconductor photocatalytic material for water pollution abatement due to its relatively narrow band gap, high abundance, and environmental friendliness. Unfortunately, rapid recombination of photogenerated carriers and low recyclability limited its effects on pollutant degradation. In this work, BiVO 4 -G/FTO bilayer films were prepared by depositing graphene-modified (G) wormlike monoclinic scheelite-type BiVO 4 -G onto the FTO (SnO 2 :F) substrates. Compared with conventional powder or bulk BiVO 4 -based photocatalytic materials, the constructed BiVO 4 -G/FTO heterostructure can effectively inhibit the rapid recombination of BiVO 4 photogenerated electron-hole pairs. Meanwhile, unique graphene-modified wormlike microscopic morphology increases the number of catalytic sites and the specific surface area. The BiVO 4 -G/FTO bilayer film exhibited photocatalytic activity up to about 3.00 times that of bare BiVO 4 and outstanding reusability, which offers new ideas for the design of photocatalysis. Tetracycline degradation under visible light has been facilitated by the employment of a worm-like bilayer film, BiVO 4 -G/FTO heterojunction, which exhibits extraordinary catalytic behavior and high recyclability. [Display omitted] • Worm-like BiVO 4 -G/FTO bilayer film heterojunctions created using the sol-gel method. • Unique worm-like bilayer film morphology increases active sites and facilitates recycling. • Graphene and FTO synergistically modulate charge transfer and enhance catalytic behavior. • BiVO 4 -G/FTO bilayer film catalysts exhibit outstanding removal efficiency and cycling stability for TC. [ABSTRACT FROM AUTHOR]

Semiconductor nano photocatalysis holds promise for remediating polluted water; nevertheless, the widespread adoption of photocatalysts is impeded by their low reaction rates and significant electron-hole recombination rates, particularly for large-scale applications. To address this, heterogeneous nano photocatalysts are crucial. Mesoporous anatase nanoparticles (ANPs) and anatase-silica nanocomposite (ASNC) were synthesized and augmented with Cu 2 O (Cu 2 O/ASNC) for photocatalytic use by sol-gel method. Thermally stable Cu 2 O/ASNC revealed the porous cauliflower-shaped nanostructure with uniform Cu distribution along with Si, and Ti. Transmission electron microscopy (TEM) depicted spherical morphologies with particle sizes of 3.5 nm for ANPs, 12.5 nm for ASNC, and 1.42 nm for Cu 2 O/ASNC. Moreover, Cu 2 O/ASNC exhibited a surface area (S BET) of ∼215 m2/g, bandgap around 2.07 eV, and formation of Cu–O–Ti bond. Cu 2 O/ASNC displayed relatively high photocatalytic activity 89 % phenol red degradation (k = 0.008 min−1) after 300 min of UV-radiation. • Mesoporous anatase-silica nanocomposite (ASNC) was synthesized and augmented with Cu 2 O for photocatalytic application. • Thermally stable Cu 2 O/ASNC revealed the porous cauliflower-shaped nanostructure with uniform Cu distribution along with Si, and Ti. • TEM depicted spherical morphologies with particle sizes of 3.5 nm for ANPs, 12.5 nm for ASNC, and 1.42 nm for Cu 2 O/ASNC. • Cu 2 O/ASNC exhibited a surface area (S BET) of ∼215 m2/g, bandgap around 2.07 eV, and formation of Cu–O–Ti bond. • Cu 2 O/ASNC displayed relatively high photocatalytic activity 89 % phenol red degradation (k = 0.008 min-1). [ABSTRACT FROM AUTHOR]

This work reports on the photocatalytic activity of tin oxide (SnO2)-doped magnesium (Mg) and fluorine (F) nanoparticles for methyl orange and safranin dye degradation under sunlight irradiation. Nanocatalysis-induced dye degradation was examined using UV–visible spectroscopy and a pseudo-first-order kinetics model. The results indicate that the prepared nanoparticles exhibit superior photocatalytic activity, and the degradation of methyl orange (MO) dye is approximately 82%. In contrast, the degradation of safranin dye is 96% in the same time interval of 105 min. The calculated crystallite size of the SnO2–Mg–F nanocomposite is 29.5 nm, which respects the particle size found in the DLS analysis with a tetragonal structure and spherical morphology affirmed. The optical characteristics were assessed, and their respective bandgap energies were determined to be 3.6 eV. The influence of F in Mg and SnO2 is recognized with the XRD and FT-IR spectra of the prepared particles.

In this article, prepared SiO2 and Se-doped SiO2 nancomposite materials have been made by using the sol–gel technique as well as their nancomposite material organisation studied toward the removal of Methyl Green (MG) dye by UV and solar irradiation as a model organic pollutant from the textile industry. The characterization included SEM, EDX, TEM, XRD, DRS, and PL analysis and measurements. The implications of process parameters, including advantages, have been analyzed at various parameters and are reported. The catalyst was found to be stable and reusable. This procedure is more cost-effective for treating industrial waste since it may be reused under solar light. As a photo electrode, Se-doped SiO2 proved its efficiency in dye-sensitized solar cell applications, and the antibacterial agar well diffusion method had very important industrial and medicinal applications.

A clay-based TiO2 nanocomposite material was synthesized by a facile method, to investigate its structure and photocatalytic efficiency. The supported TiO2 nanoparticles were generated using a sol-gel method, and subsequently, mixed with a suspension of sepiolite. The material was recovered in powder form (Mc-80) and then calcined to properly arrange the crystal lattice of the TiO2 particles for use in heterogeneous photocatalysis (Mc-80-500). A powder X-ray diffractogram of Mc-80-500 revealed a dispersion of anatase and rutile phase TiO2 particles on the clay surface, exhibiting a size in the order of 4–8 nm. TEM images of Mc-80-500 confirmed the presence of isolated TiO2 beads on the surface of the fibrous sepiolite. The specific surface area of Mc-80-500 was larger than that of raw sepiolite and that of free TiO2 nanoparticles. Mc-80-500 was found to be more efficient in heterogeneous photocatalysis compared to other TiO2 materials based on sepiolite. Total depollution of a reactive dye (Orange G) was achieved after 1 h irradiation time, which is relatively quick compared to previous reports. The photocatalyst material can be washed with distilled water without chemical additives or calcination, and can be reused several times for photocatalysis, without loss of efficiency. [ABSTRACT FROM AUTHOR]

The prepared nano ZnO and Cu-doped ZnO nanocomposite materials were prepared by the sol–gel method and were employed as photocatalysts for the degradation of Cu-doped ZnO dye in aqueous solution. The nanocomposite material was characterized by HR-SEM, EDX, HR-TEM, PL, and UV-DRS. The HR-SEM, HR-TEM, and XRD analysis studies illustrated that Cu-doped ZnO is a nanoflower and spherical-shaped structure. The PL and DRS results showed low intensity and low band gap energy, indicating high efficiency of the photocatalyst by doped material. This doped material has high degradation of Rhodamine 6G dye, which was 92%, and that of ZnO was 77%, and the prepared catalyat was stable and reusable. Other applications of DSSC, CV, and antibacterial activity were recognized and studied further. [ABSTRACT FROM AUTHOR]

In this paper, Y–ZrO2–TiO2 photocatalyst was prepared by sol–gel method, the titanium source was tetrabutyl titanate, and the precursors were zirconium nitrate pentahydrate and yttrium nitrate hexahydrate. For the photocatalytic effect of Y–ZrO2–TiO2 to hydroquinone, these effects were investigated: doping ratios of Zr/Y, calcination conditions, pH, etc. And the materials were characterized by XRD, TEM-EDS, XPS, PL, ESR, etc. The results showed that the optimum preparation conditions of Y–ZrO2–TiO2 photocatalyst were as follows: the molar ratio of doping was Ti: Zr: Y = 100:6:0.5, the calcination temperature was 500 °C, and the calcination time was 2 h; the optimum reaction conditions were as follows: the dosage of Y–ZrO2–TiO2 was 1 g/L, and pH value was 6.96. The degradation rate of hydroquinone under 365-nm UV lamp for 50 min could reach 96.58%, while the degradation rates of pure TiO2, Y–TiO2, and ZrO2–TiO2 under the same conditions were 33.95%, 79.55%, and 90.30%, respectively. It can be seen that the addition of elements Zr and Y improves the photocatalytic performance of TiO2. [ABSTRACT FROM AUTHOR]

A novel redox-active organic-inorganic hybrid material (denoted as H4TTFTB-TiO2) based on tetrathiafulvalene derivatives and titanium dioxide with a micro/mesoporous nanomaterial structure has been synthesized via a facile sol-gel method. In this study, tetrathiafulvalene-3,4,5,6-tetrakis(4-benzoic acid) (H4TTFTB) is an ideal electron-rich organic material and has been introduced into TiO2 for promoting photocatalytic H2 production under visible light irradiation. Notably, the optimized composites demonstrate remarkably enhanced photocatalytic H2 evolution performance with a maximum H2 evolution rate of 1452 μmol g−1 h−1, which is much higher than the prototypical counterparts, the common dye-sensitized sample (denoted as H4TTFTB-5.0/TiO2) (390.8 μmol g−1 h−1) and pure TiO2 (18.87 μmol g−1 h−1). Moreover, the composites perform with excellent stability even after being used for seven time cycles. A series of characterizations of the morphological structure, the photoelectric physics performance and the photocatalytic activity of the hybrid reveal that the donor-acceptor structural H4TTFTB and TiO2 have been combined robustly by covalent titanium ester during the synthesis process, which improves the stability of the hybrid nanomaterials, extends visible-light adsorption range and stimulates the separation of photogenerated charges. This work provides new insight for regulating precisely the structure of the fulvalene-based composite at the molecule level and enhances our in-depth fundamental understanding of the photocatalytic mechanism. [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO2) nanoparticles were synthesised by the modified sol–gel method at different calcination temperatures. Samples were characterized using X-ray diffraction (XRD), high-resolution transmission microscopy, scanning electron microscopy, energy dispersive X-ray analysis (EDAX), Fourier transform infrared (FTIR) spectroscopy, Brunauer, Emmett and Teller surface area analyzer (BET) and diffuse reflectance spectroscopy (DRS). Phase transformation of TiO2 nanoparticles from anatase to rutile phase with an increase in calcination temperature from 573 to 1173 K was observed from XRD analysis. Detailed structural analysis using size–strain plot and Halder–Wagner method was done for all samples. The formation of TiO2 nanoparticles was confirmed from FTIR and EDAX spectra. The TEM image of the sample calcined at 673 K showed non-spherical shaped particles having particle sizes 13.16 ± 3.35 nm. The bandgap energy calculated from DRS decreases with an increase in calcination temperature, which supports phase transformation observed in XRD analysis. The photocatalytic degradation efficiency was evaluated by monitoring the degradation of Congo red (CR) azo dye under UV light and natural sunlight. The degradation of CR dye was confirmed by analysing the FTIR spectrum of the degraded sample. The sample calcined at 673 K, in the pure anatase phase, exhibited the highest photocatalytic activity. [ABSTRACT FROM AUTHOR]

To improve light usage, Ag and Cu were co-impregnated with nano-ZnO, and the mesoporous silica gel (meso-SiO2) was chosen as the carrier. The sol-gel method was used to successfully construct a composite photocatalyst with 3 percent Ag/0.1 percent Cu/nano-ZnO/meso-SiO2. For the evaluation of the photocatalytic activity of the as-prepared catalysts, Reactive Black 5 was used as a simulated organic pollutant in aqueous. The results revealed that uniform spherical nano-ZnO particles with a diameter of 10 nm were attached to the surface and mesopore of meso-SiO2. The average pore width and specific surface area of this composite were 7.06 nm and 305 m².g-1, respectively. The optimal amount of loaded Ag and Cu were 3% and 0.1%, respectively, which resulted in around 100% removal of Reactive Black 5 after 280 min UV-light irradiation. The degradation process followed pseudo- first-order kinetics. Ag and Cu-loaded nano-ZnO/SiO2 could be advantageous for suppressing the recombination of photo-generated holes and electrons, thus improving the degradation efficiency. The constant of degradation rate and adsorption equilibrium of 3%Ag/0.1%Cu/nano-ZnO/meso-SiO2 were 0.049 min-1 and 2.14 L.g-1, respectively. After three reuses, the Ag/Cu/ZnO/meso-SiO2 photocatalyst remained very stable during the photocatalytic process with no loss of photocatalytic activity. According to the GC-MS results, a probable degradation mechanism was estimated. [ABSTRACT FROM AUTHOR]

The use of continuous photocatalytic reactor is important for sustainable water treatment technology. Photocatalyst immobilisation on supports (of varying shapes and sizes) having the desired degree of uniformity and smoothness is challenging, and is evolving. The major concerns are the geometry of the surface (which restricts the scalability of such systems) and the appropriate adhesion of the photocatalyst. Flat surface has an inherent limitation of low photocatalyst area per floor space, and poor light distribution, whereas cylindrical surfaces can overcome all these limitations. In this work, we have developed and assessed the photocatalyst coating methodology over cylindrical (quartz) surface and have prepared a modular (continuous) photocatalytic reactor. We have immobilised titanium-dioxide on the outer surface of a cylindrical quartz tube using a rotating (coating) mechanism, using the viscous sol prepared from the sol-gel method followed by heat treatment, and not with any binder to the as-synthesized powder. Various characterization techniques, including ultraviolet-diffuse reflectance spectroscopy, energy-dispersive spectroscopy, x-ray diffraction, field-emission scanning electron microscopy, optical surface profilometry, and ultraviolet–visible spectroscopy, are used to evaluate the impact of process conditions – number of layers, rotational speed, and sol viscosity, on the coating uniformity, smoothness, and layer thickness. The performance of the custom-made (modular-type) reactor is evaluated for degradation of the model molecule (pollutant). The reactor performance and capacity can be easily scaled up by parallel connections or introducing multiple coated tubes (to increase the photocatalyst area). The outcome of the work will be of immense value in scaling up the continuous large scale photocatalytic operation and treatment process. • Conformal coating of photocatalyst over cylindrical surface for immobilised reactor. • Modular design of annular-type reactor for continuous photocatalytic degradation. • Uniform illumination of the stable photocatalyst surface is achieved. • Performance of the continuous photocatalysis is established for model pollutants. [ABSTRACT FROM AUTHOR]

Using Dy2O3, C4H6CoO4·4H2O, C6H8O7·H2O and HNO3 as the main raw materials, DyCoO3 was successfully prepared by sol-gel method. The DyCoO3 were characterized by TG-DSC, XRD, SEM and FT-IR. Using azo dye methyl orange solution as simulated wastewater, the degradation activity of DyCoO3 under UV irradiation was studied by changing the synthesis temperature and illumination time. The results show that the pure DyCoO3 can be prepared from 750 °C to 1000 °C, DyCoO3 particles were relatively uniform with average grain size of 2–3 μm. The photocatalytic activity of DyCoO3 sample calcined at 800 °C was the best. When DyCoO3 photocatalytic degradation of 10 mg/L methyl orange for 60 min, the degradation rate was close to 100%. This shows that DyCoO3 is a new type of photocatalyst with high efficiency, which lays a foundation for the application of wastewater treatment. [ABSTRACT FROM AUTHOR]

Using citric acid (C6H8O7·H2O), samarium nitrate (Sm(NO3)3·6H2O) and cobalt nitrate (Co(NO3)3·6H2O) as main raw materials, the SmCoO3 samples were successfully prepared by sol-gel method. The prepared samples were characterized by thermogravimetry and differential scanning calorimetry (TG-DSC), X-ray diffractometer (XRD), scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR). Using azo dye methyl orange solution as the simulated sewage, the photocatalytic activity of SmCoO3 samples was explored at different synthesis temperatures and illumination times. The experimental results show that pure SmCoO3 samples can be prepared at a calcination temperature of 600 °C to 1000 °C. Under ultraviolet light conditions, the sample of SmCoO3 calcined at 800 °C has the best photocatalytic activity. When illumination times is 120 min, the degradation rate of methyl orange of 10 mg/L can reach more than 97%, and SmCoO3 shows good photocatalytic performance. [ABSTRACT FROM AUTHOR]

Ag x Si y O z has the potential to inhibit the recombination of photoinduced electron hole pairs via an internal electric field induced by asymmetrical Si–O tetrahedral chains. The strength of the [SiO 4 ] tetrahedral produces a very strong internal electric field for Ag 10 Si 4 O 13. Here, a novel and convenient synthetic strategy for nano-Ag 10 Si 4 O 13 based on a sol-gel method is proposed. A small band gap, an internal electric field and a small size ensure good efficiency for nano-Ag 10 Si 4 O 13 during all chemical dynamical processes, including charge excitation, charge separation and charge transfer. [ABSTRACT FROM AUTHOR]

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A clay-based TiO2 nanocomposite material was synthesized by a facile method, to investigate its structure and photocatalytic efficiency. The supported TiO2 nanoparticles were generated using a sol-gel method, and subsequently, mixed with a suspension of sepiolite. The material was recovered in powder form (Mc-80) and then calcined to properly arrange the crystal lattice of the TiO2 particles for use in heterogeneous photocatalysis (Mc-80-500). A powder X-ray diffractogram of Mc-80-500 revealed a dispersion of anatase and rutile phase TiO2 particles on the clay surface, exhibiting a size in the order of 4–8 nm. TEM images of Mc-80-500 confirmed the presence of isolated TiO2 beads on the surface of the fibrous sepiolite. The specific surface area of Mc-80-500 was larger than that of raw sepiolite and that of free TiO2 nanoparticles. Mc-80-500 was found to be more efficient in heterogeneous photocatalysis compared to other TiO2 materials based on sepiolite. Total depollution of a reactive dye (Orange G) was achieved after 1 h irradiation time, which is relatively quick compared to previous reports. The photocatalyst material can be washed with distilled water without chemical additives or calcination, and can be reused several times for photocatalysis, without loss of efficiency.

Titanium dioxide (TiO2) nanoparticles (NPs) were produced by simple sol-gel technique and annealed for 2 h in air. The impact of annealing temperature on the physical, morphological, photocatalytic, and optical properties was studied. X-ray diffraction (XRD) measurements proved that a gradual phase change from anatase to rutile occurred with increased annealing temperature. The crystal structures of the NPs were found to change at different temperatures; anatase phase at 450 °C, mixed-phase (anatase/Rutile) at 550–650 °C, and rutile phase at 750 °C. The rise in the annealing temperature improved the crystallinity of the NPs. The crystal and grain size of the NPs increased with the annealing temperature hence reducing the specific surface area due to the condensed boundaries between subunits of the NPs. As per the Kubelka-Munk equation, the bandgap reduced as the temperature elevated. The photocatalytic activity of the NPs was higher in the anatase/rutile mixed-phase than in the single anatase and rutile phase. Experimental results indicated that annealing temperature could effectively change the properties of the TiO2 NPs.