Photodegradation Of Rhodamine Research Articles

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.

Irradiation time dependent of the ZnO/GO composite formation on the photodegradation of Rhodamine B

Rhodamine B (Rh B) is one of the dyes used in the dyeing of paints, acrylic, and fabrics as well as biological products. A high concentration of Rh B is highly toxic and dangerous to living organisms when directly discharged into water. Therefore, in this study, the degradation of Rh B in water by zinc oxide/graphene oxide (ZnO/GO) composite was investigated. The zinc oxide (ZnO) was recovered from zinc ash, waste from galvanization industries, by acid leaching process using hydrochloric acid (HCl), while the graphene oxide (GO) was synthesized by modified Hummers method. The nanocomposite of ZnO/GO was synthesized using microwave irradiation and characterized by means of Field Emission Scanning Electron Microscope (FE-SEM), X-Ray Diffraction (XRD), and Fourier Transform Infrared (FTIR). The effect of irradiation time during ZnO/GO nanocomposite formation on the photocatalysis activity of the ZnO/GO in degrading Rhodamine B under UV rays was studied. The irradiation time was varied for 6, 8, and 10 minutes. The characterization results confirm that ZnO, GO, and ZnO/GO have been successfully synthesized. The ZnO/GO nanocomposite was also responsive to UV rays and able to degrade Rh B, as one of the examples of water pollutants. The highest degradation of Rhodamine B is achieved by the ZnO/GO nanocomposite prepared at 10 minutes of irradiation. The results of this study demonstrate that microwave irradiation time affects the ability of the nanocomposite to degrade Rhodamine B.

Photocatalytic degradation of Rhodamine B dye by nanostructured powder systems containing nanoencapsulated curcumin or ascorbic acid and ascorbyl palmitate liposomal.

Due to inadequate treatment and incorrect management, wastewater with dyes has a great toxic potential as an environmental liability, representing a major concern. In this context, this work aims to investigate the potential application of nanostructured powdery systems (nanocapsules and liposomes) in the photodegradation of Rhodamine B (RhB) dye, under UV and visible irradiation. Curcumin nanocapsules and liposomes containing ascorbic acid and ascorbyl palmitate were prepared, characterized, and dried using the spray drying technique. The drying processes of the nanocapsule and the liposome showed yields of 88% and 62%, respectively, and, after aqueous resuspension of the dry powders, it was possible to recover the nanocapsule size (140nm) and liposome size (160nm). The dry powders were characterized by Fourier transform infrared spectroscopy (FTIR), N2 physisorption at 77K, X-ray diffraction (XRD), and diffuse reflectance spectroscopy (DRS-UV). Under UV irradiation, 64.8% and 58.48% of RhB were removed with nanocapsules and liposomes, respectively. While under visible radiation, nanocapsules and liposomes were able to degrade 59.54% and 48.79% of RhB, respectively. Under the same conditions, commercial TiO2 showed degradation of 50.02% (UV) and 42.14% (visible). After 5 cycles of reuse, there was a decrease of about 5% for dry powders under UV irradiation and 7.5% under visible irradiation. Therefore, the nanostructured systems developed have potential application in heterogeneous photocatalysis for the degradation of organic pollutants, such as RhB, as they demonstrated superior photocatalytic performance to commercial catalysts (nanoencapsulated curcumin > ascorbic acid and ascorbyl palmitate liposomal > TiO2).

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

Taking advantage of carbonaceous composite materials in electrocatalysis or photocatalysis is a promising pathway for transforming biomass resources into sustainable energy‐conversion systems. Herein, a carbonaceous composite catalyst based on the monodispersed silver vanadate nanoparticles (Ag3VO4 NPs) modification of biomass‐derived porous carbon (named as AVO/PC) is proposed for ultrasensitive and electrochemical rapid detection of p‐nitrophenol (p‐NP) under acidic condition. The radish‐derived three‐dimensional porous carbonaceous aerogels as supporter subtly introduced in the carbonization process of alkaline activation remarkably promote the physicochemical properties of the biomass‐derived porous carbon (PC), which can provide a favorable internal surface to load Ag3VO4 NPs. Subsequently, this electrochemical behavior of AVO/PC‐modified glassy carbon electrode (AVO/PC/GCE) exhibits high sensitivity (4.95 mA mM−1 cm−2) and a varied linear detection range (1 μmol L−1 ≈ 1 mmol L−1), as well as reproducibility and stability for p‐NP. Besides, the as‐prepared AVO/PC demonstrates the enhanced photocatalytic degradation performance of rhodamine B (RhB), and the photocatalytic rate reaches to 94% in visible light irradiation. The findings should be useful for designing and constructing dual‐purpose carbonaceous composite materials with potential applications in environmental monitoring and contaminant treatment.

Hydrazine-induced synthesis of CdS nanorings for the application in photodegradation

In this paper, CdS nanorings synthesized by a facile hydrazine-induced microwave method for the photodegradation of pollutants were reported for the first time. Different reaction method, microwave power, the category and dosage of pH regulating reagent, reaction temperature and reaction time were investigated. The formation of CdS nanorings from the self-assembly of nanoparticles was attributed to the coordination of hydrazine producing the dipole–dipole interaction among the uniform nanoparticles prepared by microwave method. The crystal phase, composition, morphology and surface property of CdS nanorings were characterized. The results showed that 100 nm-sized wurtzite CdS nanorings generated with the self-assembly of 5–8 nm nanoparticles, which presented mesoporous structures. To study the influence of ring-like structures on the photocatalysis, the photodegradation of rhodamine B (RhB) with CdS nanorings and nanoparticles was compared. The results showed that, CdS nanorings displayed higher photodegradation efficiency, which were originated from more favorable band edge potential and effective electron–hole separation producing more superoxide radical and holes as active specifies. The photodegradation path of RhB contained the process of the demethylation, the decarboxylation process, the chromophore cleavage and ring-open reactions. Finally, the available photodegradation of multiple pollutants and reusability of CdS nanorings were carried out.

Dramatic change in the photocatalytic activity of nanocrystalline La1-xNaxFeO3 (x = 0.0, 0.1, 0.2 and 0.3) perovskite oxides by the incorporation of Cu for effective removal of dyes

Wastewater treatment is a major issue that must be addressed since it damages nature and has a negative impact on living creatures. Dyes are the top most organic pollutants in wastewater that poses serious dangers to human health and the environment today. Therefore, the aim of this study is to eliminate these colored effluents, which are present in substantial amounts in wastewater, either singly or in mixtures. In this contest, we are reporting the synthesis of nano photocatalysts La1-xNaxFeO3 (x = 0.0, 0.1, 0.2 and 0.3) via sol-gel process and their corresponding Cu composite analogues by a simple chemical reduction method for the removal of dyes in aqueous solution. The prepared photocatalysts were thoroughly characterised using PXRD, BET, SEM, UV-DRS and VSM to investigate the structural, morphological, optical and magnetic properties. All the magnetic parameters (MS, MR &HC) increase with Na doping in both bare and nanocomposites. The photocatalytic activity of La1-xNaxFeO3 nano catalysts and their Cu composites was assessed through the photodegradation of rhodamine B (RhB) dye in aqueous solution under visible light. The outcomes exhibited that Cu nano composites showed excellent photocatalytic activity compared to the pristine materials due to their low band gap energies (1.61 eV). Moreover, the most active photocatalyst LaFeO3@Cu showed excellent stability after five runs, which demonstrated good stability and reusability. Because of exciting photocatalytic results, the study was further extended to the degradation of a few other organic dye contaminants such methylene blue (MB), methyl orange (MO) and their mixture using LaFeO3@Cu catalyst.

Design and Development of Novel Composites Containing Nickel Ferrites Supported on Activated Carbon Derived from Agricultural Wastes and Its Application in Water Remediation

Recently, efficient decontamination of water and wastewater have attracted global attention due to the deficiency in the world's water sources. Herein, activated carbon (AC) derived from willow catkins (WCs) was successfully synthesized using chemical modification techniques and then loaded with different weight percentages of nickel ferrite nanocomposites (10, 25, 45, and 65 wt.%) via a one-step hydrothermal method. The morphology, chemical structure, and surface composition of the nickel ferrite supported on AC (NFAC) were analyzed by XRD, TEM, SEM, EDX, and FTIR spectroscopy. Textural properties (surface area) of the nanocomposites (NC) were investigated by using Brunauer-Emmett-Teller (BET) analysis. The prepared nanocomposites were tested on different dyes to form a system for water remediation and make this photocatalyst convenient to recycle. The photodegradation of rhodamine B dye was investigated by adjusting a variety of factors such as the amount of nickel in nanocomposites, the weight of photocatalyst, reaction time, and photocatalyst reusability. The 45NFAC photocatalyst exhibits excellent degradation efficiency toward rhodamine B dye, reaching 99.7% in 90 min under a simulated source of sunlight. To summarize, NFAC nanocomposites are potential photocatalysts for water environmental remediation because they are effective, reliable, and reusable.

MIL-53(Fe)@perylene Diimide All-Organic Heterojunctions for the Enhanced Photocatalytic Removal of Pollutants and Selective Oxidation of Benzyl Alcohol

Organic semiconductors are promising materials for the photocatalytic treatment of pollutants and organic synthesis. Herein, MIL-53(Fe)@perylene diimide (PDI) organic heterojunctions were constructed by ultrasonic assembly using PDI as the co-catalyst, and PDI organic supramolecular material was uniformly distributed on the surfaces of MIL-53(Fe). The most effective M53@PDI-20 organic heterojunctions achieved 72.7% photodegradation of rhodamine B (10 mg/L) within 50 min and a 99.9% reduction in Cr(VI) (10 mg/L) for 150 min, and the corresponding apparent degradation rate constants were higher than a single component. Meanwhile, the conversion rate of benzyl alcohol over M53@PDI-20 achieved 91.5% for 5 h with a selectivity of above 90% under visible light exposure, which was more than double that of PDI. The well-matched band structures and the strong π–π bonding interactions between MIL-53(Fe) and PDI can increase the electron delocalization effect to facilitate the transfer and separation of photogenerated carriers. Lots of oxidative reactive species (h+, •O2− and •OH) also played a great contribution to the strong oxidation capacity over the heterojunctions system. This work suggests that MIL-53(Fe)@PDI organic heterojunctions may be a promising material for pollutant removal and organic synthesis.

Enhanced Toxic Dye Degradation Using Single Crystal Zn-doped Fe3O4 Octahedrons

In the present work, single crystalline octahedral Zn-doped Fe3O4 was prepared through a simple hydrothermal method and then analyzed. The possible mechanism for the formation of Zn-doped Fe3O4 octahedrons is discussed. Their photo-Fenton activity in photodegradation of Rhodamine B under visible light was sequentially investigated. The physicochemical properties of prepared ferrites were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The analysis of the results showed that synthesized products are uniform Zn-doped Fe3O4 octahedrons with high crystallinity. The experimental results manifested that Ostwald ripening processes and N2H4∙H2O amount plays an important role in the formation of the octahedrons. Also, octahedral Zn-doped Fe3O4 exhibited high photocatalytic capacity for dye degradation. • Zn-doped Fe3O4 octahedral-shaped were prepared by solvothermal method. • Ostwald ripening and N2H4.H2O play the important role in the formation of octahedral photocatalyst. • The catalysts exhibit high photo-Fenton activity. • Rhodamine degradation showed no significant change during four successive cycles.

Synergistic role of metal oxide loading cocatalysts on photocatalytic degradation of organic pollutants and inactive bacteria over template-free ZnFe2O4 nanocubes

For wastewater treatment, a highly reliable and ecologically friendly oxidation method is always preferred. This work described the production of a new extremely effective visible light-driven Ag2Ox loaded ZnFe2O4 nanocomposties photocatalyst using a wet impregnation technique. Under visible light irradiation, the produced Ag2Ox loaded ZnFe2O4 nanocomposties were used in the photodegradation of rhodamine B (RhB) and Reactive Red 120 (RR120) dyes. Analysis using X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy revealed that Ag2Ox nanoparticles were well dispersed on the surface of ZnFe2O4 NPs and that the Ag2Ox loaded ZnFe2O4 NPs were created. When compared with bare ZnFe2O4 NPs, Ag2Ox-loaded ZnFe2O4 nanocomposites showed better photocatalytic activity for RhB and RR120 degradation under visible light (>420 nm) illumination. The reaction kinetics and degradation methodology, in addition to the photocatalytic degradation functions of Ag2Ox-loaded ZnFe2O4 nanocomposites, were thoroughly investigated. The 3 wt% Ag2Ox loaded ZnFe2O4 nanocomposites have a 99% removal efficiency for RhB and RR120, which is about 2.4 times greater than the ZnFe2O4 NPs and simple combination of 1 wt% and 2 wt% Ag2Ox loaded ZnFe2O4 nanocomposites. Furthermore, the 3 wt% Ag2Ox loaded ZnFe2O4 nanocomposites demonstrated consistent performance without decreasing activity throughout 3 consecutive cycles, indicating a potential approach for the photo-oxidative destruction of organic pollutants as well as outstanding antibacterial capabilities. According to the findings of the experiments, produced new nanoparticles are an environmentally friendly, cost-efficient option for removing dyes, and they were successful in suppressing the development of Gram-negative and Gram-positive bacteria.

Enhancement of NIR-triggered photocatalytic activity of Ln3+-doped NaYF4@SiO2/Ag@TiO2 nanospheres through synergistic upconversion and plasmonic effect

The multishell-structured NaYF4:Yb,Tm,Nd@NaYF4:Yb,Nd@SiO2/Ag@TiO2 (UC@SiO2/Ag@TiO2) nanospheres were prepared for the first time, which possessed the enhanced NIR-triggered photocatalytic activity under the synergistic effect of upconversion and plasmons. The design of active-core@active-shell structure for NaYF4:Yb,Tm,Nd@NaYF4:Yb,Nd upconversion nanophosphors (Yb/Tm/Nd@Yb/Nd UCNPs) significantly improved their upconversion luminescence (UCL) efficiency, which was increased by 12 times after coating a Yb/Nd shell on Yb/Tm/Nd seed crystals via epitaxial growth. After introduction of Ag nanoparticles, the UCL intensity of the obtained UC@SiO2/Ag was further enhanced by 3.3 times compared with the bare UCNPs because the plasmon resonance frequency of Ag overlapped with the visible emission peaks of UCNPs, which permitted an effective surface plasmon-coupled emission, resulting in the increase of emission intensity for UCNPs. Therefore, the final UC@SiO2/Ag@TiO2 could absorb the plasmon-enhanced NIR-to-UV/Vis lights from UCNPs to obtain its photocatalytic activity. Significantly, the photodegradation of Rhodamine B under the action of UC@SiO2/Ag@TiO2 was 26.9 % higher than that under the action of UC@SiO2@TiO2. UC@SiO2/Ag@TiO2 also exhibited a better photocatalytic antibacterial activity against B. subtilis than UC@SiO2@TiO2. In the presence of UC@SiO2/Ag@TiO2, bacteria were completely killed after 15 min of 808 nm NIR illumination. Finally, the possible photocatalytic mechanism of UC@SiO2/Ag@TiO2 was discussed based on the results of scavenger test.

Fast and efficient green synthesis of CaWO4 NPs using eggshells as a biogenic calcium source: Structure, optical property, and morphology

In summary, we report a fast, easy, and low-cost green synthesis approach to obtain calcium tungstate nanoparticles (CaWO4NPs_GS) using eggshells as a source of calcium by the sonochemistry method at room temperature. These nanomaterials were structurally characterized by X-ray diffraction (XRD) and Rietveld refinement analysis, where a pure phase with very close structural parameters with calcium tungstate nanoparticles was synthesized at the conventional route (CaWO4NPs_CS). All vibrational Raman active modes characteristic of symmetry point C4h6 were confirmed. An optical band gap value (Egap = 3.92(2) eV) for CaWO4NPs_GS lower than for CaWO4NPs_CS (Egap = 3.92(2) eV) was archived, and that is associated with the intermediate electronic levels due to the oxygen vacancy and micro-strain effect. Field Emission Scanning Electron Microscopy (FE-SEM) images show several nanoparticles with a particle size of 62.7 ± 1.3 nm for CaWO4NPs_CS and 48.7 ± 1.2 nm for CaWO4NPs_GS, where all elements characteristic of calcium tungstate (Ca, W, and O) were appointed by Energy Dispersive X-ray (EDX) analysis. While the photocatalytic performance of CaWO4NPs_GS was 2.5 times faster than CaWO4NPs_CS in the photodegradation of Rhodamine B (RhB) dye in an aqueous solution under UV light in 120 min. Therefore, confirming that chicken eggshell is a promissory raw material as a biogenic source of calcium ions for synthesizing calcium tungstate with promissory photocatalytic properties.

Constructing recyclable photocatalytic BiOBr/Ag nanowires/cotton fabric for efficient dye degradation under visible light

In this study, a highly-efficient photocatalytic and recyclable BiOBr/Ag nanowires (AgNW)/cotton fabric (CF) composite was fabricated by successive ionic layer adsorption and reaction (SILAR) for rapid treatment of dye wastewater. The integration of AgNW and BiOBr aims to establish a channel for faster and easier charge transfer to enhance the photocatalytic performance. The chemical structure and morphology of BiOBr/AgNW/CF, as well as its photo-degradation of Rhodamine B (RhB) under visible light radiation were explored. Results reveal that BiOBr/AgNW/CF exhibits remarkably enhanced photocatalytic activity over BiOBr/CF, which degrades 97 % of RhB within 90 min. BiOBr/AgNW/CF still maintains 88 % of photocatalytic degradation capacity after five reusing cycles due to the effective encapsulation of BiOBr that protects AgNW from oxidation. Photoluminescence, electron spin resonance, and free radical trapping experiments confirm that the separation efficiency of photo-generated electron-hole pairs plays an important role in improving photocatalytic performance. In all, this work exhibits great potential in the development of textile-based photocatalytic materials that integrates two significant merits, the high degradation efficiency and easy recovery.