RhB Dye Research Articles

Sodium alginate hydrogel-encapsulated trans-anethole based polymer: Synthesis and applications as an eradicator of metals and dyes from wastewater

Clean and safe water resources are essential for environmental safety and human health. Hydrogels and biomass polymers have attracted considerable attention in recent years, considering their nontoxicity, controllable performance, and high adsorption capacity. The interpenetrating network described here is a combination of a biomass polymer and a hydrogel adsorbent was established, the biomass polymer microspheres were first prepared with the combination of biomass monomer trans-anethole and maleic anhydride copolymer. A simple, environmentally friendly, and facile method of incorporating biomass polymer into sodium alginate biopolymer was developed by introducing the cross-linking agents calcium chloride and glutaraldehyde into the biomass polymer. Furthermore, the biomass polymer sodium alginate hydrogel (BP@SA/H) was characterized by FTIR, XPS, SEM, and XRD. In order to test materials' performance, the removal of pollutants and the adsorption study were also investigated after and before adsorption toward metals and dyes in water. We examined the factors influencing the materials, adsorption capability, such as initial concentration, time, absorbent amount, and pH. Moreover, the maximum adsorption values for Pb+2 and Cd+2 were 734.9 and 722 mg/g. While the adsorption toward RhB dye are 745 mg/g. In addition, the adsorption results were investigated using kinetic and isothermal models, demonstrating that biomass polymer hydrogel adsorption is chemisorption. Therefore, the as-developed biomass polymer sodium alginate hydrogel (BP@SA/H) is an exceptional multifunctional material that can be used to remove hazardous pollutants from wastewater.

Insight into the relationship between the photostability and molecular structure of rhodamine dyes

It is still challenging to clarify the intrinsic relationship between the photostability and molecular structures of rhodamine dyes. Herein, we investigated the photostability of three rhodamine dyes RhB, Rh101, and Rh101-ME in water and 20%EtOH–H2O solutions under 525 nm LED light irradiation. The photostability of RhB is much higher than that of Rh 101 and Rh101-ME, indicating that forming rigid ring between the N-linked alkyl and xanthene can significantly decrease the photostability of rhodamine dyes, while the esterification of carboxyl on benzene ring can improve their photostability. The EPR analyses and radical trapping experiments proved that 1O2 is the most important reactive oxygen species responsible for dye degradation, and the Rh101 and Rh101-ME have higher 1O2 and •OH production rates than RhB. The cyclic voltammetry tests showed that forming rigid ring between the N-linked alkyls and xanthene can decrease the oxidation potential of RhB and consequently lower down its photostability. The theoretical calculations disclosed that the higher HOMO energy levels in ground states and lower singlet–triplet energy gaps of Rh101 and Rh101-ME are the main factor that results in their lower photostability when compared with RhB.

Hierarchical structure of 3D ZnO experimentally designed to achieve high performance in the sertraline photocatalysis in natural waters

Hierarchical nanostructures of 3D ZnO are considered great potential materials for many technological applications. In this study, we employed a chemometric approach to investigate the detailed effects of the synthetic parameters in the obtaining of ZnO. We applied the microwave-assisted solvothermal method of high control. Using Central Composite Design (CCD) and Principal Component Analysis (PCA) we identified that the proportions of solvents and physical parameters, efficiently controlled, were responsible for the formation of 3D ZnO structures in only 10 min. The physical–chemical properties of the nanostructures were characterized by XRD, Raman, HR-TEM, XPS, FTIR, MEV-EDS, FEG, DRS, Mott-Schottky and other methods, which led to the discovery of important characteristics that were treated by chemometry. As a consequence, the materials were efficient to produce •OH and O2•–, reaching high performance in sertraline (SRTL) degradation in up to five cycles of application. The transformation products (TP) were followed by mass spectrometry analysis, which allowed us to describe in detail the SRTL degradation mechanisms. The degradation efficiency after 5 cycles decreases by only 20% without any treatment on the recovered photocatalyst before reapplication. Photocatalytic studies using RhB dye reached 100% efficiency in 45 min under UV-C and 99% in 75 min under UV-A, showing that the photocatalyst has excellent performance for different classes of organic pollutants and light sources. In addition, phytotoxicity assays proved that by-products formed in the SRTL degradation process are not toxic to the Cucumis sativus species, proving the safety of using this photocatalyst for wastewater treatment. Therefore, the experimentally designed synthesis method is an alternative to obtaining hierarchical 3D ZnO structures that showed high efficiency for the SRTL degradation in environmental matrices.

Tailoring Homogeneous Hydrogel Nanospheres by Facile Ultra-Sonication Assisted Cross-Linked Copolymerization for Rhodamine B Dye Adsorption.

The present paper describes the design of shape-oriented hydrogel nanospheres using a facile ultrasonication-supported crosslinked copolymerization technique. The effect of variable monomer concentration on the homogeneity of hydrogel nanospheres was investigated. The chitosan-cl-poly(MMA) hydrogel nanospheres were well characterized using various techniques such as FTIR, XRD, TGA, SEM, and TEM. The chitosan-cl-poly(MMA) hydrogel nanospheres were studied for their swelling behavior and could potentially be used as a novel adsorbent for rhodamine B dye remediation from aqueous media. The study found that utilizing chitosan-cl-poly(MMA) nanohydrogel spheres at the optimal pH 5 increased RhB dye adsorption capacity from 7.9 to 17.8 mg/g (pH 2 to 5), followed by a slight reduction. Furthermore, when nanohydrogel concentration increased, adsorption capacity dropped from 18.03 to 2.8 mg/g, but adsorption percentage climbed from 90.2% to 97.8%. At an initial dye concentration of 140 mg/L, rhodamine B adsorption achieved 204.3 mg/g in 60 min. The rhodamine B dye adsorption study includes adsorption kinetics, isotherm, and thermodynamics analyses. The interpretation of the adsorption study revealed that Langmuir isotherms fit best with a qmax value of 276.26 mg/g, which is in close approximation with the experimental value, whereas pseudo-second-order kinetics explains the adsorption process rate. The interaction of RhB dye with chitosan-cl-poly(MMA) hydrogel nanospheres involves multiple forces such as electrostatic interactions, hydrogen bonding, van der Waals forces, etc.

Synthesis of cellulose cotton-based UiO-66 MOFs for the removal of rhodamine B and Pb(II) metal ions from contaminated wastewater

The presence of pollutants in drinking water has become a significant concern recently. Various substances, including activated carbon, membranes, biochar, etc., are used to remove these pollutants. In the present study, a new composite comprising cotton fabric and a mixture of Metal-Organic Frameworks (MOFs) was synthesized and used as an adsorbent for eliminating pollutants from wastewater. At first, the UiO-66 MOFs were prepared by a simple method of reacting Zirconium (IV) chloride (ZrCl4) and p-Phthalic acid (PTA) after successful preparation of UiO-66 then modified its surface with amino functional groups by reacting with APTES to obtain UiO-66-NH2. Moreover, the cellulose cotton fabric (CF) surface was modified with Polydopamine (PDA) and obtained CF@PDA. Further, with the help of EDC-HCl and NHS, the UiO-66-NH2 grafted on the surface of the CF@PDA and finally obtained CF@PDA/UiO-66-NH2. In addition, the adsorption study was performed toward RhB dye and Pb(II) metal ion pollutants. The maximum adsorption toward RhB dye was 68.5 mg/g, while toward Pb(II) metal ions was 65 mg/g. In addition, the kinetic study was also conducted and the result favoured the Pseudo-second order kinetic study. The adsorption isotherm was also studied and the Langmuir model was more fitted as compared with the Freundlich model. Moreover, the material has excellent regeneration and recycling ability after ten cycles. The significant adsorption ability, the novel combination of cotton and MOFs, and the recycling feature make our material CF@PDA/UiO-66-NH2 a promising potential absorbent material for wastewater treatment and even in other important areas of water research.

Advancing sustainable solutions: Harnessing polyaniline/BiOCl/GO ternary nanocomposites for solar-powered degradation of organic pollutant and photocatalytic hydrogen generation

Recently, polyaniline-based photocatalysts have gained great attention due to their narrow band gap (E = 1.77 eV), which enables them to absorb a significant amount of visible light (∼43%) in the solar spectrum. In this study, we have synthesized a ternary nanocomposite (PANI/BiOCl/GO) through an oxidative polymerization approach, incorporating polyaniline (PANI), graphene oxide (GO), and bismuth oxychloride (BiOCl). Different weight percentages of composites (GO/BiOCl: 0.5%, 1%, 2.5%, and PANI: 99.5%, 99%, 97.5%) were prepared and named as 0.5PBG, 1PBG, and 2.5PBG, respectively. The ternary nanocomposite's successful development, crystallinity, purity, porosity, and optical properties were evaluated through several spectroscopic and surface analysis techniques, including UV–Vis-DRS, PL, XRD, XPS, BET, and EDS analysis. FESEM and HRTEM images unveiled the porous characteristics of PANI, the morphology of exfoliated GO layers, and the nanoplate-like structure of BiOCl. The ternary nanocomposite was finally tested for its ability to degrade an organic dye, rhodamine-b (Rhb), and in the process also generate solar-light-driven green hydrogen by water half-splitting. The composite achieved about 90% detoxification (assigned from GC-TCD by analyzing the evolved CO2 gas after degradation) and 96% color removal of Rhb dye within 120 min. The degradation of Rhb by 1PBG displayed a first-order reaction, featuring a rate constant 7.25 times higher than that observed for pure PANI, 3.8 times higher than for pure GO, and 3.9 times higher than for pure BiOCl. Thus, the ternary composites achieve a good amount of synergy. Significantly, this reaction rate constant is 4.7 times greater than the rate observed with commercially used TiO2–P25 photocatalyst. Various reaction parameters including solution pH, different illumination areas, catalyst dosage, and the study of scavengers were investigated to understand their effects on the degradation reaction. The photocatalyst's reusability effectiveness was evaluated over 6 cycles, and its stability was subsequently confirmed through XRD and ICP-OES analysis. The LC-MS study revealed the identification of various intermediates and end products following the degradation reaction. The nanocomposite also produced 1000 ppm of hydrogen gas with an apparent quantum efficiency (AQE) of 17.97% when CH3OH was used as a sacrificial agent, 500 ppm (AQE of 9.69%) in the acidic conditions, and 600 ppm (AQE of 11.63%) in the basic conditions. In a broader perspective, this endeavor paves the way for exploring fresh opportunities in the utilization of this ternary nanocomposite. Its potential extends beyond accelerating dye degradation to encompass diverse solar-driven applications as well.

First fluorine doping of In2O3 films and its crucial role in enhancing photocatalytic activity

We prepared In2O3 film on the wire mesh of stainless steel by a facile hydrothermal method followed by annealing. To enhance the visible-light-responsive photocatalytic activity of the prepared In2O3 film, we in-situ doped the element fluorine by adding FTO glass as the fluorine source during the hydrothermal process. The prepared In2O3 and F-doped In2O3 films were characterized by XRD, SEM, HRTEM, XPS, UV–vis spectra, PL, and electrochemical measurement. The results show that In2O3 octagonal pyramids of cubic phase were formed. The fluorine doping promoted to growth of In2O3 pyramids and porous In2O3 pyramids help to adsorb RhB dye molecules. Beside, the fluorine doping introduced a new impurity level between the VB and CB of In2O3, thereby, decreasing the bandgap value from 2.84 to 2.60 eV. As a result, it extended the visible light absorption range and more photoinduced electrons and holes can be excited under simulated sunlight. Moreover, the doping inhibited the recombination of photogenerated carriers. It is worth noting that the fluorine doping changed the surface state of In2O3 and enhanced the chemical adsorption of dissociated oxygen species. It finally made RhB dye molecules strongly adsorbed the surface of F-doped In2O3 film. The photocatalytic activity of the F-doped In2O3 film was increased by 7.6 times compared with the pristine In2O3 film because of the combined action of the above reasons. The importance of active groups for RhB photodegradation is O2•− > h+ > e− > •OH.

Novel 3D@2D/2D HHSS@BiOBr/Znln2S4 S-scheme photocatalyst for efficient adsorption-photocatalytic-photosensitization synergistic degradation of organics

Constructing high-performance multifunctional visible-light-driven photocatalysts to remediate organic contaminants from wastewater is of great challenge. Herein, we report a novel 3D@2D/2D hierarchical heterogeneous structured HHSS@BiOBr/Znln2S4 (HBZ) with abundant sulfur vacancies nanocomposite. This unique photocatalyst was fabricated by in situ growth of BiOBr nanosheets on the surface of hierarchical hollow silica spheres (HHSS), followed by epitaxial growth of Znln2S4 nanosheets for effective degradation of TCH and RhB. The optimal sample HBZ-6 (60 wt% Znln2S4) exhibited adsorption-photocatalytic synergistic degradation rate up to 92.36% after 30 min visible light irradiation, which was 2.31 times higher than that of bare BiOBr. It is benefit from the strong adsorption capacity of HHSS and effective carrier separation of 2D/2D S-scheme BiOBr/Znln2S4 in the HBZ-6 photocatalyst. Furthermore, it was surprising to discover that the coloured dye RhB was 100% photodegraded by HBZ-6 photocatalyst in 2 min under visible light, which is much faster than that of TCH with low visible light absorption. This excellent degradation efficiency is attributed to adsorption-photocatalytic-photosensitization synergistic between RhB and HBZ-6, leading to the ultrafast dye-sensitized-assisted electron transfer process. This work provides progressive tactics to design 3D@2D/2D defect heterogeneous structures which can greatly promote the future development of catalytic systems for wider application.

Synergistic modulation of oxygen vacancies and carbon atoms in TiO2 via a simple pot‐in‐pot reaction for improved visible‐light‐driven photocatalytic performances

AbstractNovel synthesis methods are urgently expected for visible‐light‐driven photocatalysts. Hereby we report a series of TiO2‐based photocatalysts (T‐x) by using a simple pot‐in‐pot reaction approach. In this approach, two reaction media are isolated from each other by the crucible reactor. The obtained T‐x sample shows nanosheet‐aggregate structure and wide visible‐light absorption property with an optimal bandgap of 2.35 eV. Factors that influence the bandgap modulation, including nitrogen, fluorine, carbon and oxygen vacancy etc., are discussed in detail. Characterization results demonstrate a substantial increase of oxygen vacancies and carbon atoms in T‐x sample, which were proven to the main reason for the extended visible‐light absorption and enhanced photocatalytic performance. Under visible‐light irradiation, T‐x sample shows excellent photocatalytic degradation activity for RhB with a k value of 0.027 min−1 and good photoelectrochemical performance. Trapping experiments reveal that ⋅OH are the main active species to oxidize the RhB dye. This new pot‐in‐pot reaction approach enables synthesis of novel photocatalytic materials with wide visible‐light‐response.

A facile synthesis of Ag incorporated Bi2O3/CuS nanocomposites as photocatalyst for degradation of environmental contaminants

Binary Bi2O3/CuS (2, 3 & 5 wt%) and ternary Bi2O3/CuS (3 %)/Ag (3, 10 & 15 wt%) nanocomposites were successfully prepared by a facile precipitation and deposition methods. The prepared materials were characterized for different features by using various techniques in a matter of structure (XRD), constitutional elements (EDX), morphology characteristics (FESEM and HRTEM), optical (PL and UV-DRS) and photocatalytic properties. The photocatalytic performance of the prepared nanocomposites was tested on the organic pollutant, RhB dye. Bi2O3/CuS/Ag nanocomposites resulted the maximum activity in the acidic medium (99.3 % in 60 min) as compared to basic (10.9 % in 60 min) and neutral (1.22 % in 60 min) medium. As photocatalysts, ternary nanocomposite Bi2O3/CuS (3 wt%) /Ag (10 wt%) showed highest performance in degradation (99.3 % degradation in 60 min) than binary Bi2O3/CuS (3 wt%) sample (97.2 % degradation in 60 min). The increased photocatalytic efficiencies due to the refinement in the absorbance and obtained band gap in visible region (2.14 eV) and formation of heterojunctions due to which lifetime of the photo-induced electron-hole species is intensified by the decrement in recombination. Active species involved in the degradation reaction were also examined by scavenger studies and follows the order: holes > superoxide anion radical > hydroxyl radical.

Mn-doped BaFe12O19 nanoparticles synthesis via micro-emulsion route: Solar light-driven photo-catalytic degradation of CV, MG and RhB dyes and antibacterial activity

A pristine and Mn-doped BaMnxFe12-xO19 (x =0.0–0.3) NMs were synthesized via a facile micro-emulsion route. The impact of substitution was assessed across various properties including structure, ferroelectric behavior, dielectric characteristics, photocatalytic performance, and antibacterial activity. X-ray diffraction analysis confirmed the presence of a single-phase hexagonal structure of barium hexaferrite (BHF). The P-E analysis revealed the high coercivity, Remnant polarization and maximum polarization of doped materials versus pure BaFe12O19. Doping led to a reduction in the energy bandgap, consistent with the observed increase in polarization. The photocatalytic activity (PCA) of pure BaFe12O19 (BHF) was compared with highly substituted BaMn0.3Fe12O19 (BMHF5) for the degradation of Crystal Violet, Malachite Green and Rhodamine B dyes under visible light irradiation. The doped BMHF5 exhibited superior PCA (94.6, 92.2 and 96.5 (%) for CV, MG and RhB dyes, respectively). The doped material also showed promising antibacterial activity. Owing to the promising enhanced optical properties, BMHF5 has the potential for the treatment of wastewater under solar light irradiation.

Zircon-Type CaCrO4 Chromite Nanoparticles: Synthesis, Characterization, and Photocatalytic Application for Sunlight-Induced Degradation of Rhodamine B.

The degradation of organic dye pollutants is a critical environmental issue that has garnered significant attention in recent years. To address this problem, we investigated the potential of CaCrO4 chromite (CCO) as a photocatalyst for the degradation of cationic and anionic dye solutions under sunlight irradiation. CaCrO4 was synthesized via a sol-gel auto-combustion route and sintered at 900 °C. The Rietveld refined XRD profile confirmed the zircon-type structure of CaCrO4 crystallized in the tetragonal unit cell with I41/amd space group symmetry. The surface morphology of the sample was investigated by field emission scanning electron microscopy (FESEM), which revealed the polyhedral texture of the grains. Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) studies were carried out to analyze the elemental composition and chemical states of the ions present in the compound. Fourier transform infrared (FT-IR) spectroscopy analysis revealed the vibrational modes corresponding to the tetrahedral and dodecahedral metal oxide bonds. The optical band gap was approximated to be in the range of 1.928 eV by using the Tauc relation. The CaCrO4 catalyst with different contents (5, 20, 35, and 50 mg) was investigated for its photocatalytic performance for the degradation of RhB dye solution under sunlight irradiation using a UV-Vis spectrometer over the experimental wavelength range of 450-600 nm. The degradation efficacy increased from 70.630 to 93.550% for 5-35 mg and then decreased to 68.720% for 50 mg in 140 min under visible light illumination. The comparative study demonstrates that a higher degradation rate was achieved for cationic than anionic dyes in the order RhB > MB > MO. The highest deterioration (93.80%) was achieved for the RhB dye in 140 min. Equilibrium and kinetic studies showed that the adsorption process followed the Langmuir isotherm and pseudo-second-order models, respectively. The maximum adsorption capacity of 21.125 mg/g was observed for the catalyst concentration of 35 mg. From the cyclic test, it has been observed that the synthesized photocatalyst is structurally and morphologically stable and reusable. The radical trapping experiment demonstrated that superoxide and hydroxyl radicals were the primary species engaged in the photodegradation process. A possible mechanism for the degradation of RhB has been proposed. Hence, we conclude that CaCrO4 can be used as an efficient photocatalyst for the remediation of organic dye pollutants from the environment.

Sunlight driven photocatalytic degradation of RhB dye using composite of bismuth oxy-bromide kaolinite BiOBr@Kaol: Experimental and molecular dynamic simulation studies

This study reported the synthesis of a new eco-friendly photocatalyst nanocomposite based on kaolinite clay and bismuth oxybromide (BiOBr@Kaolinite) using a facile co-precipitation method in acidic medium. The prepared nanocomposite was characterized using several techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning microscopy electron (SEM), Transmission electron microscope (TEM), Energy-dispersive X-ray spectroscopy (EDX), UV–Vis diffuse reflectance spectra (DRS), and X-ray photoelectron spectroscopy (XPS). These techniques were used to determine the crystal phase, functional groups, morphology, elementary composition, chemical states, optical properties, and bad gap energy of as synthesized, respectively. The characterized materials were then applied for rapid photodegradation of Rhodamine B dye (RhB), indicating its effective use for the degradation of toxic organic pollutants under sunlight irradiation. The photocatalytic activity study showed that RhB dye (10 mg/L) was degraded within 30 min under sunlight irradiation. The degradation mechanism of RhB and the photocatalytic stability study of the nanocomposite BiOBr@0.4Kaol showed that, the high photocatalytic activity could be attributed to the charge transfer from kaolinite to BiOBr nanoparticles, which prevented the rapid recombination of the electron-hole pair induced during the photocatalytic process. Moreover, MD and DFT-D stimulations and adsorption calculations based on Monte Carlo were applied in this study. This study led to the development of an effective and environmentally friendly photocatalyst nanocomposite for the degradation of toxic organic pollutants in wastewater, highlighting its potential application in water treatment and depollution processes.

Rare earth ions (La3+, Nd3+) substituted cobalt–strontium spinel ferrites for photocatalytic degradation of textile dyes

Abstract In the industrial sector, productive and effective treatment of toxic dye-based color pollutants is a key issue. Lanthanum and neodymium substituted cobalt–strontium (Co–Sr) spinel ferrite (Co0.5Sr0.5RExFe2-xO4, x = 0.00 and 0.06) catalysts were synthesized and used to degrade Congo red and rhodamine B dyes from an aqueous solution mixture in this study. For this specific purpose, RE3+ ions substituted Co–Sr spinel ferrite nanoparticles with photocatalytic degradation ability were prepared through sol–gel method. The degradation of CR and RhB in recently synthesized nanoferrites was also examined. SEM and XRD were used to characterize the prepared samples. The optical band gap values of synthesized spinel ferrites were examined with the help of Tauc plots by using UV-visible absorption. It was determined that the energy bandgap ranged from 2.91 to 2.52 eV. For Co0.5Sr0.5Fe2O4, Co0.5Sr0.5La0.06Fe1.94O4, and Co0.5Sr0.5Nd0.06Fe1.94O4 nanoferrites, the rates of CR and RhB dye degradation were 73–90% and 45–85%, respectively, at pH 5–7. The kinetics models successfully described the degradation reaction as pseudo-first-order kinetics. It was, therefore, concluded that the prepared samples can be used as effective photocatalysts in order to eliminate hazardous pollutants present in wastewater.

Preparation, catalytic efficiency and mechanism of Fe3O4/HNTs heterogeneous Fenton-like catalyst

In situ anchor of Fe3O4 nanoparticles (NPs) onto the external surface of natural halloysite nanotubes (HNTs) was achieved by a simple one-pot solvothermal method. The Fe3O4/HNTs composites were characterized by XRD, SEM, TEM, FT-IR, VSM, and N2 adsorption-desorption. Characterization results showed that the magnetic Fe3O4 NPs formed tightly on the external surface of HNTs with good dispersion. Fe3O4/HNTs composites exhibited typical ferromagnetic property determined by VSM tests and could be recovered by an external magnet. Degradation experiments were conducted using the active dye RhB as the target probe to evaluate the Fenton-like catalytic efficiency of Fe3O4/HNTs composites obtained under different preparation conditions. The experimental results indicated that the degradation efficiency of RhB could reach more than 98 % within 10 min reaction time, when the initial pH was 3.5, initial RhB concentration was 100 mg L−1, H2O2 concentration was 1.96 mmol L−1, and catalyst dosage was 0.5 g L−1, realizing the rapid degradation of high concentration dye. Comparative investigations revealed that the Fenton-like catalytic efficiency of Fe3O4/HNTs for degrading high concentration RhB was much higher than that of Fe3O4 NPs. The heterogeneous Fenton-like catalytic mechanism of Fe3O4/HNTs was elucidated. Hydroxyl radicals (•OH) and superoxides radicals (•O2-) dominated the RhB degradation in the Fe3O4/HNTs-H2O2 system.

STRUCTURAL, OPTICAL, AND VISIBLE-LIGHT DRIVEN PHOTACATALYTIC PROPERTIES OF Yb-DOPED BiVO4 NANOPARTICLES PREPARED VIA RAPID SONOCHEMICAL PROCESS

This work represents the synthesis and structural, morphological, and optical characterization of rare-earth Yb-doped BiVO4 materials with different Ytterbium (Yb3+) contents (0% - 5%). Yb-doped BiVO4 specimens in form of fine nanoparticles were synthesized by a rapid and facile sonochemical process. The structural and morphological characterizations were observed by X-ray diffraction technique (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Important optical properties of the prepared samples were investigated by the diffuse reflectance technique and the corresponding optical band gaps were calculated by the mean of the Kullbelka-Munk equation. From the characterized results, it is acknowledged that incorporated Yb dopant has a significant effect on the crystalline structure of BiVO4 by reducing in monoclinic phase in the pristine sample while the increasing Yb doping composition resulted in the mixed phases of monoclinic and tetragonal phases since Yb3+ ions could probably induce the stabilization of the tetragonal phase in BiVO4 material. Moreover, extensive doping with Yb3+ exhibits considerable influence on not only structural but also optical and relevant visible - driven photocatalytic properties of BiVO4 by means of the color degradation of RhB dye solution.

CeO2-decorated reduced graphene oxide for lubricative, anticorrosive and photocatalytic purposes

CeO2 decorated reduced graphene oxide (CeO2@rGO) nanocomposites synthesized using a hydrothermal method were studied for their tribological, anti-corrosive and photocatalytic applications. Results showed that CeO2 nanoparticles with an average diameter of ∼12.24 nm were uniformly distributed and covalently bonded onto the surface of rGO. When the nanocomposites were added into PAO5w-40 lubricating oil, the coefficient of friction in the friction test was 31.9% lower than that using the pure lubricating oil. The corresponding wear mechanism was changed from oil-film lubrication to reaction film lubrication, which is mainly attributed to the filling effect of nanostructured CeO2 powers and lubrication effect of rGO. The nanocomposites were also added into chromium-free Dacromet coating and the corrosion current density in the corrosion test was decreased by an order of magnitude. This is mainly due to the formation of various chemical bonds and passivation layer on the modified coating, which improves its density. It is also attributed to the uniformly dispersed rGO, which forms a conductive channel, resulting in the preferred corrosion of the Zn–Al alloy in the coating thus achieving an effective protection effect to the substrate. When the composites were applied as the photocatalyst in an RhB solution under the irradiation of ultraviolet light, the RhB dye was effectively removed with an efficiency up to 90.5%, because the rGO can extend the life time of active electron-hole pairs and prevent CeO2 nanoparticles from severe agglomeration.

1,10-Phenanthroline-5-amine derived N-doped carbon dots for long-lived visible-light-activated room temperature phosphorescence in the matrix and information encryption application

Room temperature phosphorescence (RTP) materials have received a lot of attention. However, it is still a challenge to realize the practical application of RTP excited under visible light. Herein, five different carbon dots (CDs) were prepared using 1,10-phenanthroline-5-amine (Aphen) as the co-carbon source and nitrogen source, and several polymer-based RTP films were prepared by simple doping. It was found that the phosphorescence emission behavior of polymer films was changed by the surface state structure of different CDs. Non-radiative transition of the triplet excitons of Aphen structure on the CDs surface was effectively inhibited by the hydrogen bonding interaction and the fixed domain-limiting effect of the polymer matrix. Meanwhile, the Aphen structure was bound to the CDs through covalent interaction, which further suppressed the molecular vibration, realizing the efficient organic RTP. The phosphorescence lifetime of the prepared ACCDs-PVA films reached 352.88 ms with a photoluminescence quantum yield of 36.7%. In addition, the dye RhB was co-doped in the ACCDs-PVA system to modulate the afterglow color of the materials via the triplet to single-state energy resonance transfer (TS-FRET) process. Finally, we also developed stable ACCDs-EPO RTP material by exploiting the dense three-dimensional network structure and hydrophobic property of the cured epoxy resin (EPO) matrix. The as-constructed long-lived RTP materials can be employed in information encryption.

Enhanced piezocatalytic performance of (Bi1/2Na1/2)(1-x)BaxTiO3 piezoelectric material with morphotropic phase boundary for degradation of RhB

Piezoelectric catalysis has been considered a promising technology in water pollution control. In this report, environmental-friendly (Bi1/2Na1/2)(1-x)BaxTiO3(BNBT-x) piezoelectric materials with the morphotropic phase boundary (MPB) were prepared by one-step solvothermal method. The piezocatalytic activities of the BNBT-x piezoelectric materials were examined by the degradation of RhB dye solution. The results demonstrate that the BNBT-6 catalyst with the MPB exhibit a higher piezocatalytic performance of up to 98.95% compared to pure BNT. In addition, the BNBT-6 catalyst exhibits good reusability, which is of great significance for practical applications. This work opens a route to design and develops high-performance piezocatalysts.

Contrasting photocatalytic performance of quantum-dot sensitized p-type and n-type TiO2 hierarchical nanocomposites under visible light

In recent times, titanium dioxide (TiO2) has acquired greater attention owing to its efficient photocatalytic activity, low cost, stability, non-corrosive, high availability, and nontoxicity towards the environment and humans. However, two major drawbacks including a wide band gap of around ∼3.2 eV and a high recombination rate of the photogenerated charge carriers restrict its capability in practical application. In this work, we deposited metal chalcogenide-based quantum-dots of lead sulfide (PbS QDs) on P25-, p-type and n-type TiO2 nanoparticles by pseudo-successive ionic layer adsorption and reaction (p-SILAR) process to form hierarchical nanocomposite and studied the corresponding photocatalytic activity under visible light. Concurrently, improved optoelectronic characteristics were recorded for n-TiO2/PbS hierarchical nanocomposite due to low charge recombination evidenced from photoluminescence (PL) spectra and optimum PbS deposition evidenced from EDX analysis as compared to p-TiO2 and P25–TiO2. The n-TiO2/PbS hierarchical nanocomposite degrades 74.4% RhB dye under visible light in 120 min. The structural, morphological, and photocatalytic characteristics were investigated by scanning and transmission electron microscopy, PL spectra, UV–Vis spectrophotometry, and Fourier transforms infrared spectra. This work might offer new understandings on P25-, p- and n-TiO2/PbS hierarchical nanocomposites with improved photocatalytic performance for visible-light activated degradation of RhB.