Photodegradation Of Rhodamine Research Articles

Magnetic separation, sunlight-driven photocatalytic activity, and antibacterial studies of Sm-doped Co0.33Mg0.33Ni0.33Fe2O4 nanoparticles.

Magnetic nanoparticles have emerged as a promising tool for wastewater treatment due to their unique properties. In this regard, Co0.33Mg0.33Ni0.33SmxFe2-xO4 (0.00 x 0.08) nanoparticles were prepared to examine their magnetic separation efficiency (MSE), photocatalytic, antibacterial, and antibiofilm performances. Pure nanoparticles, having the highest saturation magnetization (Ms = 31.87emu/g), exhibit the highest MSE, where 95.6% of nanoparticles were separated after 20min of applying a magnetic field of 150 mT. The catalytic performance of the prepared samples is examined by the photodegradation of rhodamine B (RhB) dye exposed to direct sunlight radiation. Improved photocatalytic activity is exhibited by Co0.33Mg0.33Ni0.33Sm0.04Fe1.96O4 nanoparticles, labeled as Sm0.04, where the rate of the degradation reaction is enhanced by 4.1 times compared to pure nanoparticles. Rising the pH and reaction temperature improves the rate of the photodegradation reaction of RhB. The incorporation of 15 wt% reduced graphene oxide (rGO) with Sm0.04 enhanced the rate of the reaction by 1.7 and 2.4 times compared with pure Sm0.04 sample and rGO, respectively. The antibacterial and antibiofilm activities against Escherichia coli, Leclercia adecarboxylata, Staphylococcus aureus, and Enterococcus faecium are assessed by the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) broth microdilution, the agar well diffusion, the time-kill assays, the biofilm formation, and destruction assays. The bacteria used in these assessments are isolated from wastewater. The nanoparticles exhibit a bacteriostatic activity, with a better effect against the Gram-positive isolates. Co0.33Mg0.33Ni0.33SmxFe2O4 (x = 0.00) nanoparticles have the best effect. The effect is exerted after 2-3h of incubation. Gram-positive biofilms are more sensitive to nanoparticles.

Optimization of preparation conditions of Bi-doped TiO2/montmorillonite composites and its photodegradation of Rhodamine B

In order to improve the photocatalytic degradation performance of titanium intercalated montmorillonite composites, the sol-gel method was used to intercalate bismuth/titanium polymerized hydroxyl cations into the interlayer of sodium-based montmorillonite (Na-MMT). The optimum synthesis conditions of Bi-doped TiO2/montmorillonite composite photocatalytic material (Bi/Ti-MMT) were investigated. Powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM) and UV–vis diffusion reflectance spectrum (UV-Vis DRS) had been used to study the formation of Bi/Ti-MMT. Under the conditions of Bi/Ti molar ratio of 7 %, montmorillonite suspension mass fraction of 2 %, calcination temperature of 600 ℃ and calcination time of 3 h, the Bi/Ti-MMT had the highest photocatalytic activity, the degradation rate of Rhodamine B (RhB) was 88.16 %. In Bi/Ti-MMT composites, TiO2 existed in anatase phase. Bi3+ replaced Ti4+ and was doped into the TiO2 lattice, which can inhibit the growth of TiO2 crystals and reduce the band gap. The photoresponse range of the composite material was broadened to visible light, which improved the utilization of light.

Charge-Selective Photocatalytic Degradation of Organic Dyes Driven by Naturally Occurring Halloysite Nanotubes

This study explores the use of Halloysite NanoTubes (HNTs) as photocatalysts capable of decomposing organic dyes under exposure to visible or ultraviolet light. Through a systematic series of photocatalytic experiments, we unveil that the photodegradation of Rhodamine B, used as a model cationic dye, is significantly accelerated in the presence of HNTs. We observe that the extent of RhB photocatalytic degradation in 100 min in the presence of the HNTs is ~four times higher compared to that of bare RhB. Moreover, under optimized conditions, the as-extracted photodegradation rate of RhB (~0.0022 min−1) is comparable to that of the previously reported work on the photodegradation of RhB in the presence of tubular nanostructures. A parallel effect is observed for anionic Coumarin photodegradation, albeit less efficiently. Our analysis attributes this discrepancy to the distinct charge states of the two dyes, influencing their attachment sites on HNTs. Cationic Rhodamine B molecules preferentially attach to the outer surface of HNTs, while anionic Coumarin molecules tend to attach to the inner surface. By leveraging the unique properties of HNTs, a family of naturally occurring nanotube structures, this research offers valuable insights for optimizing photocatalytic systems in the pursuit of effective and eco-friendly solutions for environmental remediation.

Photocatalytic Performances of ZnS/g-C3N4 Nanocomposites with Different Mass Ratios

In this study, we prepared a series of ZnS/graphitic-C3N4 nanocomposites in various mass percentages and morphological properties of all the nanocomposites were examined by utilizing SEM/EDX technique. The photocatalytic performances of ZnS/graphitic-C3N4 nanocomposites were evaluated by degradation of Rhodamine B molecules under visible light. The photocatalytic performances of all nanocomposites under various photocatalyst dosages and initial Rhodamine B concentrations were further investigated for determination of optimal conditions.the obtained results indicated that ZnS/graphitic-C3N4 nanocomposites show almost 2 times higher photocatalaytic performances than pure graphitic-C3N4 and ZnS nanoparticles. The scavenger studies showed that the superoxide radicals had a major role in the photodegradation and the photodegradation of Rhodamine B follows the pseudo-first-order kinetic.

Effect of acidic and basic leachants on the synthesis of ZnO nanoparticles from Egyptian zinc ore, their optical/surface characteristics and photocatalytic performance

It is of pivotal significance to optimize the parameters affecting the extraction of metals from natural ores to convert them to value-added products. Owing to their semiconducting nature, most metal oxides, including ZnO, have various electronic, optical, and photocatalytic applications. Hence, we are investigating the leaching of Zn from Smithsonite (an Egyptian ore) using acidic/basic leaching agents (leachants). The leached salts were employed in a co-precipitation method followed by calcination to obtain crystalline ZnO nanoparticles. Both photocatalytic performance of the ZnO nanoparticles obtained from acid leaching and basic leaching were investigated toward the photodegradation of Rhodamine B dye. The ZnO(A) prepared using the acid leaching route has achieved about 5.6-fold enhancement in the dye photodegradation% and 5.3-fold enhancement in the observed rate constant compared to ZnO(B) prepared from basic leaching. Finally, the superior photocatalytic activity of the ZnO(A) is attributed to the smaller particle size, larger surface area, and existence of some defects that enhanced the photocatalytic performance.

Investigation of the Photocatalytic Performance, Mechanism, and Degradation Pathways of Rhodamine B with Bi2O3 Microrods under Visible-Light Irradiation.

In the present work, the photodegradation of Rhodamine B with different pH values by using Bi2O3 microrods under visible-light irradiation was studied in terms of the dye degradation efficiency, active species, degradation mechanism, and degradation pathway. X-ray diffractometry, polarized optical microscopy, scanning electron microscopy, fluorescence spectrophotometry, diffuse reflectance spectra, Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, UV-visible spectrophotometry, total organic carbon, and liquid chromatography-mass spectroscopy analysis techniques were used to analyze the crystal structure, morphology, surface structures, band gap values, catalytic performance, and mechanistic pathway. The photoluminescence spectra and diffuse reflectance spectrum (the band gap values of the Bi2O3 microrods are 2.79 eV) reveals that the absorption spectrum extended to the visible region, which resulted in a high separation and low recombination rate of electron-hole pairs. The photodegradation results of Bi2O3 clearly indicated that Rhodamine B dye had removal efficiencies of about 97.2%, 90.6%, and 50.2% within 120 min at the pH values of 3.0, 5.0, and 7.0, respectively. In addition, the mineralization of RhB was evaluated by measuring the effect of Bi2O3 on chemical oxygen demand and total organic carbon at the pH value of 3.0. At the same time, quenching experiments were carried out to understand the core reaction species involved in the photodegradation of Rhodamine B solution at different pH values. The results of X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and X-ray diffractometer analysis of pre- and post-Bi2O3 degradation showed that BiOCl was formed on the surface of Bi2O3, and a BiOCl/Bi2O3 heterojunction was formed after acid photocatalytic degradation. Furthermore, the catalytic degradation of active substances and the possible mechanism of the photocatalytic degradation of Rhodamine B over Bi2O3 at different pH values were analyzed based on the results of X-ray diffractometry, radical capture, Fourier-transform infrared spectroscopy, total organic carbon analysis, and X-ray photoelectron spectroscopy. The degradation intermediates of Rhodamine B with the Bi2O3 photocatalyst in visible light were also identified with the assistance of liquid chromatography-mass spectroscopy.

Enhanced photocatalytic activity of SnO2/g-C3N4 nanocomposite synthesized using sonochemistry method

The SnO2/g-C3N4 nanocomposite materials were successfully synthesized via the solid reaction and sonochemistry methods. The properties of the obtained product were investigated using several methods: X-ray diffraction, UV-vis diffuse reflectance spectroscopy, and Scanning electron microscope. The photocatalytic properties of the samples were evaluated through the photodegradation of Rhodamine B solution. The results demonstrate that the SnO2/g-C3N4 prepared by the sonochemistry method exhibits higher photocatalytic activity than that prepared by the solid reaction method. This enhanced photocatalytic activity is attributed to the formation of heterostructures between SnO2 and g-C3N4 materials, resulting in the efficient separation of photo-generated electron-hole pairs. Furthermore, the nanocomposite exhibits a larger specific surface area compared to the product obtained through the solid reaction method.

Facile preparation and characterization of Zn2Ti3O8/g-C3N4 nanocomposites for degradation of rhodamine B under simulated sunlight

Zinc titanate (Zn2Ti3O8, ZTO) was initially synthesized using a straightforward and inexpensive Pechini approach, and subsequently Zn2Ti3O8/g-C3N4 (ZTO/CN) nanocomposites with varied contents were created using an ultrasonic-assisted co-precipitation process. Based on the appropriate bandgaps (2.0 eV and 2.7 eV), the photodegradation of rhodamine B (RhB) was studied. This is the first time that ZTO/CN nanocomposites are studied for the degradation of organic pollutants. The results showed that the best performance belonged to the sample with a mass ratio of 0.25 to 1 among different ZTO/CN nanocomposites. Therefore, 50 mg of ZTO/CN (0.25:1) degraded 89.0 % of 10 ppm RhB. Scavenger testing revealed that superoxide radicals and holes played significant parts in photodegradation processes.

Post-Synthetic Modifications of Ti(IV)-Based Metal-Organic Frameworks for Enhanced Photocatalysis and Conductivity

Metal-Organic Frameworks (MOFs) are coordination networks with organic ligands containing potential voids, ideal for guest-host interactions. These unique characteristics make them interesting materials for several different applications, including catalysis. Unfortunately, most MOFs feature metal oxide nodes that are insulting by nature, which limits their potential in electro- and photochemical catalysts. To combat these issues, post-synthetic modifications (PSM) can be used to tune MOF properties. This research reports on different PSMs incorporated into the Ti(IV)-based MOFs MIL-125(Ti) and MIL-125(Ti)-NH2. PSMs that introduce intentional defect states and dopant metal ions, such as Ce(IV), were explored to determine their influence on the photo-degradation of Rhodamine B in aqueous solution. Post-Synthetic Metal Exchange (PSME) was used to incorporate Ce(IV) at the Ti(IV) sites in MIL-125(Ti) and MIL-125(Ti)-NH2, and intentional defect states were introduced using formic acid during MOF synthesis. In addition, conductive organic polymers were utilized to make novel polymer-MOF hybrid composites that showed enhanced charge transport properties compared to pristine MOF. Ultimately, these results show how PSMs can be used to impart conductivity and enhance photocatalysis in the MOFs MIL-125(Ti) and MIL-125(Ti)-NH2.

Efficient utilization of ceramic waste (cyclone dust waste) for enhancing the photocatalytic performance of TiO2 nanoparticles toward Rhodamine B photodegradation

Owing to the increase in the world's population, industrial demands are significantly increasing, and air/water pollution has become a global threat that severely affects human health. Many pollutants are discharged into the ecosystem, ceramic dust/wastes cause air pollution and textile dyes are among the recalcitrant organic water pollutants. This requires efficient waste management and waste remediation. Photocatalysis is one of the most efficient technologies for treating organic pollutants, where TiO2 nanoparticles are the most widely used photocatalysts. However, the wide bandgap and rapid e-h recombination rates of TiO2 nanoparticles impede their practical applications. Herein, we are hitting “two birds with one stone” by utilizing ceramic waste powder in the fabrication of photocatalysts to degrade organic pollutants. The employed ceramic waste “cyclone dust waste (CDW)” was used as filler materials during the sol-gel synthesis of TiO2 photocatalyst. The synthesis method is a facile and cost-effective route because CDW was employed as obtained from the production line without any further processing. Different loading percentages of CDW were in-situ added to the TiO2 during the synthesis. x%CDW-TiO2 samples were investigated toward the photodegradation of Rhodamine B dye as a primary pollutant model, where 30%CDW-TiO2 nanocomposite was the optimum sample that achieved 2.6-fold enhancement in the RB photodegradation% compared to the bare TiO2. The physicochemical properties of the as-fabricated samples were investigated using different techniques, including XRD, HR-TEM, FE-SEM, DRS, and PL. It was found that the as-prepared CDW extended the light absorption capability of the 30%CDW-TiO2 nanocomposite toward the visible light. The PL results showed the reduction of e-h recombination rate in 30%CDW-TiO2 nanocomposite owing to the constructed Type-II/Z-scheme heterojunction. This work will open the door to the investigation of different wastes to be used as filler materials to be incorporated in the synthesis of value-added compounds.

Microwave assisted eco-benign synthesis of novel palladium nanoparticles (ACPs-PdNPs): A new insight into photocatalytic and biomedical applications

The increasing bacterial infections and water contamination are the most critical global challenge. To address these challenges, innovative approaches are required to generate safe and effective nanoscale materials that inhibit the growth of microbes and remove hazardous contaminants from water. In this study, we described for the first time the eco-benign synthesis of acid protease mediated palladium nanoparticles (ACPs-PdNPs) using Melilotus indicus leaf extract. A series of physicochemical characterizations were applied to evaluate the size, shape and crystalline structure of ACPs-PdNPs. The surface Plasmon resonance (SPR) peak at 343 nm examined in the U.V spectra and the FTIR peaks at 591 cm¯1 confirmed the formation of as prepared NPs. Moreover, the ACPs-PdNPs possessed an extremely small particle size (5–30 nm), brown in color with spherical morphology. The as-synthesized nanoparticles were screened for their biological activities and photocatalytic applications. The catalytic efficiency of ACPs-PdNPs were inquired by the photodegradation of Rhodamine B (Rh. B) dye. Based on the findings, only 20 min of irradiation were enough to degrade 99 % of Rh. B. The ACPs-PdNPs demonstrated exceptional antibacterial activity against Escherichia coli (E. coli) bacteria in both light and dark environments, with inhibition zones of 33 mm and 27 mm, respectively. In addition, 1,1-diphenyl-2-picryl-hydrazil (DPPH) radical scavenger potential of these nanoparticles was quite strong by scavenging 88 % of the DPPH radicals. Furthermore, the Michigan Cancer Foundation (MCF-7) women's breast cancer cell lines were strongly inhibited by the acid protease mediated ACPs-PdNPs with the IC50 value of 66.37 µg/mL. Due to their trivial size and substantial surface area, ACPs-PdNPs exhibited exceptional photocatalytic and biomedical applications.

Simple and fast synthesis of BiOBr/[Bi6O5(OH)3](NO3)5·3H2O composites for efficient photocatalytic degradation of RhB under visible light

In this study, a heterostructure photocatalyst consisting of Bi6O5(OH)3](NO3)5·3H2O (was denoted as BiOOHN) and BiOBr was fabricated via a simple and economic co-precipitation method. In this method, the amount of Br in the composition was controlled by changing the volume of hydrobromic acid (HBr) during the manufacturing process. The photocatalytic performance of the prepared samples by photodegradation of rhodamine B (RhB) solution under visible light radiation was investigated and the optimum amount of HBr was obtained. The results showed that BiOBr/BiOOHN composite has higher photocatalytic efficiency compared to pure BiOOHN and BiOBr, so that almost 100 % of RhB solution was degraded in the presence of BiOBr/BiOOHN composite photocatalyst during 100 min, while this value was equal to 0 % and 21 % for pure BiOOHN and BiOBr, respectively. Results indicated that the BiOOHN band gap is in the ultraviolet region (3.45 eV) and not possible to activate this sample to generate electron-hole pairs under visible radiation. While the energy gap of the samples synthesized in the presence of HBr was around 2.90 eV, which enables the activation of these compounds under visible radiation to generate electron-hole pairs for photocatalytic reactions. Therefore, the weak BiOOHN photocatalytic performance is attributed to the its wide band gap energy in comparison with other samples. Also, the better performance of composite samples compared to pure BiOBr is owing to the formation of a heterostructure between BiOOHN and BiOBr. It leads to better separation of electron-hole pairs at the interface of two semiconductors and hinders their recombination, which improves photocatalytic performance. Also, a mechanism for the photocatalytic reactions of RhB degradation was proposed based on experimental data and the experiment of trapping active species. According to this mechanism, the holes and free hydroxyl radicals (•OH) play a key role in the photocatalytic degradation reactions of RhB.

Morphological evaluation and boosted photocatalytic activity of N-doped ZnO nanoparticles prepared via Co-precipitation method

Pristine and nitrogen (N) doped zinc oxide (ZnNxO1-x, x = 0, 0.005, 0.01, and 0.02) nanoparticles (NPs) were successfully synthesized using chemical co-precipitation approach. The formation of pure crystalline wurtzite ZnO phase without any second phase during N-doping was confirmed by X-ray diffraction (XRD) analysis of N-doped ZnO samples. X-ray photoelectron spectroscopic (XPS) analysis ensured the effective inclusion of nitrogen into ZnO matrix. The morphological analysis revealed the formation of nanorods as a result of N-doping. The optical band gap calculated from UV–vis spectroscopy was observed to decrease up to 1 mol.% N doping followed by a subtle increase. Photoluminescence (PL) spectra revealed that electron-hole recombination was the least for 1 mol.% N doped ZnO NPs. ZnN0.01O0.99 NPs showed superior photocatalytic activity among all samples due to rod-shaped NPs and reduced electron-hole recombination, which was accessed by the photodegradation of Rhodamine B (RhB).

Chitosan/hybrid ceria supported nickel nanoparticles: Study of magnetic and optical properties, photodegradation of rhodamine B, and antimicrobial activity, with DFT

In this study, we explore the magnetic and optical properties of nickel nanoparticles decorated with chitosan/hybrid ceria (iron doped ceria) alongside their potential use in the photodegradation of rhodamine B dye. To support our experimental results, we use Density Functional Theory (DFT) analysis. In addition, the antibacterial activity of the synthesized nanocomposite is evaluated. The hybrid nanoparticles have interesting magnetic and optical characteristics, which make them a viable option for a variety of applications. The chitosan hybrid ceria-nickel nanoparticles also successfully photodegrade the dye rhodamine B, suggesting their potential uses in environmental remediation. Additionally, the nanocomposite antimicrobial activity against the gram-positive Streptococcus pneumoniae and gram-negative Klebsiella pneumonia, which cause a variety of diseases including pneumonia, urinary tract infection, sinusitis, osteomyelitis, meningitis, and septic arthritis, was evaluated demonstrating the nanocomposite ability to fight infectious infections. Overall, this paper thoroughly evaluates the nickel nanoparticles supported on the chitosan hybrid ceria, emphasizing their various features and prospective uses.

Photodegradation of Rhodamine B using gallium hybrids as an efficient photocatalyst.

Keeping in view the toxicity of the Rhodamine B, the present study is designed to remediate the water loaded with toxic dyes using gallium oxide and gallium hybrids as photocatalyst. Precipitation coupled with sonochemical method is adopted for the synthesis of gallium oxide while the post grafting method is adopted for the synthesis of gallium hybrids with the indole and its derivatives. FTIR spectra showed the characteristic absorption bands of gallium oxide and gallium hybrids at 400-700cm-1 and 1400-1600cm-1. SEM and XRD showed the micro-sized rectangular rod-shaped gallium oxide with rhombohedral geometry. The average crystallite size of gallium hybrids was 26-32nm calculated using the Debye Scherrer and Williamson-Hal models. The BET isotherm of gallium hybrids revealed the adsorption type-IV and hysteresis loop (H3) proposing multilayer and mesoporous structures with increase in surface area from 26 m2/g of gallium oxide to 31 m2/g of gallium-indole, 35 m2/g of gallium-methyl indole, and 37 m2/g of gallium-carboxylic indole. XPS showed the presence of gallium (3-14%), oxygen (28-32%), nitrogen (23-46%), and carbon (9-46%). The gallium oxide and gallium hybrids showed 47-72% optimum degradation of Rhodamine B under 2h of illumination at pH 7 and 0.03mg/L. The degradation rate followed a Langmuir-Hinshelwood model with R2 > 0.9.

Photodegradation of Rhodamine B and Phenol Using TiO2/SiO2 Composite Nanoparticles: A Comparative Study

Organic pollutants found in industrial effluents contribute to significant environmental risks. Degradation of these pollutants, particularly through photocatalysis, is a promising strategy ensuring water purification and supporting wastewater treatment. Thus, photodegradation of rhodamine B and phenol under visible-light irradiation using TiO2/SiO2 composite nanoparticles was within the main scopes of this study. The nanocomposite was synthesized through a wet impregnation method using TiO2 and SiO2 nanopowders previously prepared via a facile sol–gel approach and was fully characterized. The obtained results indicated a pure anatase phase, coupled with increased crystallinity (85.22%) and a relative smaller crystallite size (1.82 nm) in relation to pure TiO2 and SiO2 and an enhanced specific surface area (50 m2/g) and a reduced energy band gap (3.18 eV). Photodegradation of rhodamine B upon visible-light irradiation was studied, showing that the TiO2/SiO2 composite reached total (100%) degradation within 210 min compared to pure TiO2 and SiO2 analogues, which achieved a ≈45% and ≈43% degradation rate, respectively. Similarly, the composite catalyst presented enhanced photocatalytic performance under the same irradiation conditions towards the degradation of phenol, leading to 43.19% degradation within 210 min and verifying the composite catalyst’s selectivity towards degradation of rhodamine B dye as well as its enhanced photocatalytic efficiency towards both organic compounds compared to pure TiO2 and SiO2. Additionally, based on the acquired experimental results, ●O2−, h+ and e− were found to be the major reactive oxygen species involved in rhodamine B’s photocatalytic degradation, while ●OH radicals were pivotal in the photodegradation of phenol under visible irradiation. Finally, after the TiO2/SiO2 composite catalyst was reused five times, it indicated negligible photodegradation efficiency decrease towards both organic compounds.

Decoration of Monodisperse Silver Vanadate on Biomass‐Derived Porous Carbon: A Dual‐Purpose Catalyst for Detection of p‐Nitrophenol and Photodegradation of Rhodamine B

Decoration of Monodisperse Silver Vanadate on Biomass‐Derived Porous Carbon: A Dual‐Purpose Catalyst for Detection of p‐Nitrophenol and Photodegradation of Rhodamine B

Synthesis of zinc oxide photocatalysts from zinc-dust waste for organic dye degradation

Zinc-dust waste from a hot-dip galvanizing plant in the metal plating industry was successfully used as the starting material to synthesize zinc oxide (ZnO) nanopowder via a hydrothermal method. Effects of acid types in zinc-dust dissolving process and concentration of NaOH for precipitation on physical characteristics and photocatalytic activity of the synthesized ZnO were investigated. Elemental composition, phase and crystallite size, morphology with chemical composition, and specific surface area of the ZnO nanostructures were characterized by X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), and gas adsorption-desorption analysis, respectively. The photocatalytic performance of the prepared ZnO was evaluated by photodegradation of rhodamine B (RhB) under UV light irradiation. The ZnO nanostructures synthesized by dissolving zinc-dust with nitric acid, then precipitating with a solution of 6 M NaOH, and hydrothermal treatment at 170℃ for 8 h exhibited the highest dye degradation efficiency. It is up to 89.7% after UV irradiation for 240 min, which is comparable to the degradation efficiency of a commercial ZnO nanoparticles (92.7%). This work offers materials and synthesis method for alternative photocatalysts prepared from industrial waste that possess high photocatalytic activity for organic dye degradation.

Novel Sol-Gel Synthesis of TiO2 Spherical Porous Nanoparticles Assemblies with Photocatalytic Activity.

For this study, the synthesis of TiO2 nanomaterials was performed via a novel sol-gel method employing titanium butoxide as a metal precursor, Pluronic F127 as a templating agent, toluene as a swelling agent, and acidic water or ethanol as the reaction solvents. The method was designed by tailoring certain reaction parameters, such as the sequence of toluene addition, magnetic stirring, the type of reaction solvent, and the calcination conditions. Analysis of the specific surface area and porosity was carried out via N2 physisorption, whereas the morphological features of the solids were investigated via transmission electron microscopy. The crystalline structure of both the dried powders and the calcined materials was evaluated using X-ray diffraction analysis. It transpired that the different phase compositions of the solids are related to the specific synthesis medium employed. Under the adopted reaction conditions, ethanol, which was used as a reaction solvent, promoted the local arrangement of dispersed anatase particles, the specific arrangement of which does not lead to rutile transformation. Conversely, the use of water alone supported high-particle packing, evolving into a rutile phase. The photodegradation of Rhodamine B was used as a target reaction for testing the photocatalytic activity of the selected samples.

Controlled Architectures in Supported Photocatalysis: Exploring the Potential of Cold Plasma Discharge, Additive Manufacturing, and Fractal Geometry to Form Hierarchically Immobilized Ni-MOF/BiOI/AgVO3.

Herein, we explore the potential of innovative manufacturing techniques based on green chemistry principles, for the fabrication of convenient, performant, and stable supported photocatalysts to be used for water depollution. After giving some insight into the use of fractal geometry for the fabrication of tunable polymer supports for photocatalysts, we investigated the use of liquid crystal display (LCD) 3D printing to generate the fractal resin substrates to be used for the immobilization of semiconductor photocatalysts. Notably, confocal laser imaging was used as a first attempt for assessing the surface area of the fractal substrate. Immobilization methods based on cold plasma discharge (CPD) were employed to modify the surface of the polymer substrates and permanently anchor three different phases, namely, nickel-based metal-organic framework (Ni-MOF), BiOI, and AgVO3, in a hierarchical configuration. Herein, for the first time, we developed a plasma-initiated condensed in situ complexation-assisted precipitation (c-ISCAP) method that allowed 2D Ni-MOF to be synthesized directly onto the surface of a polymer substrate, in a single step. Not only this MOF coating was found to be strongly bound to the surface of the polymer substrate but also very uniform and fully functional, even when other inorganic phases were immobilized on the top of this layer. This chemical approach opens the way for the fabrication of hybrid materials with complex polymer substrates and MOF coatings that could be used in a range of possible applications, for instance as chemical sensors, electrodes, adsorbents, optical devices, etc. Our hybrid photocatalysts were tested via photodegradation of Rhodamine B (RhB) dye upon visible light activation, with recycling runs to assess their durability. It was found that the hierarchical heterojunction Ni-MOF/BiOI/AgVO3 showed an outstanding ability for the removal of RhB dye, owing to the activity of the Ni-MOF layer in terms of charge transfer, and also partly because of its adsorbing potential. The three photoactive phases demonstrated a strong synergistic effect through coupling. However, more importantly, our findings show that their immobilization itself, regardless of the method used, significantly modified their optoelectronic properties, hence most likely changing the overall mechanism of charge transfer in the heterojunction. The Ni-MOF phase, notably, was found to display a reduced bandgap when obtained by c-ISCAP, which contributed to enhance its activation by visible light irradiation. Finally, it was established that the fractal geometry had a significant impact on the efficiency of the supported catalysts, probably thanks to an increased immobilization ratio of photocatalyst mostly, owing to the larger surface area available.