Solution Of Rhodamine Research Articles

Application of Three-Dimensional Porous Aerogel as Adsorbent for Removal of Textile Dyes from Water

The textile industry is one of the most important industries in the European Union. The main environmental problems of the textile industry are the high water consumption, the generated pollution, the variety of chemicals used and the high energy demand. Recently, adsorbents with a large specific surface area and low weight, such as aerogels, have attracted great interest as promising materials for removing dyes from polluted water. Cellulose aerogels are inexpensive and non-toxic. Langmuir and Freundlich isotherms were chosen as the best method to describe the performance of the adsorbent. In this study, the adsorption efficiency of Congo red, Naphthol green B, Rhodamine B and Methylene blue were determined by using an adsorbent synthesized from paper and cardboard waste. The total organic carbon concentration was chosen as an indicator of the concentration of the dyes in the solutions. The aerogel capsules had 5% cellulose content. It was found that the adsorption capacity of the aerogel in the solutions of Congo red varied from 0.028 mg/g to 14.483 mg/g; in the solutions of Naphthol green B, from 0.013 mg/g to 7.698 mg/g; in the solutions of Rhodamine B, from 0.020 mg/g to 8.768 mg/g; and in the solutions of Methylene blue, from 0.024 mg/g to 13.538 mg/g.

Visible-light-driven BiOI and GO/BiOI photocatalysts for organic pollutants degradation and hydrogen production using low power sources

BiOI and (3 wt%)GO/BiOI visible-light-driven photocatalysts were obtained by a one-pot solvothermal method and successfully applied to the degradation of single and binary dye solutions of rhodamine B (RhB) and methylene blue (MB) and H2 production using very low-power sources. The GO/BiOI with hierarchical flower morphologies exhibited the highest activity, achieving RhB and MB photodegradation percentages (%Xdye) of 100% and 80%, respectively, in 240 min employing a simple 19 W white LED array. Furthermore, GO/BiOI dosage and RhB initial concentration play an essential role in dye degradation, and scavenger assays confirmed that holes and superoxides are the main species causing RhB oxidation. TOC analysis determined an efficiency of 70%, and after three uses, the GO/BiOI attained a %XRhB of 84%. The H2 evolution was performed under 2 W UV light, yielding 323.25 μmol/h∙g of H2 for BiOI, and the addition of GO nanosheets increased the photoactivity of GO/BiOI up to 63% (509.61 μmol/h∙g). The catalytic activity of GO/BiOI is superior to values reported in the literature considering nominal power consumption (kWh) vs. efficiency of RhB degradation or H2 production.

High-throughput fluorescence quantification method based on inner filter effect and fluorescence imaging analysis

The application of the inner filter effect (IFE) in fluorescent substance determination is gaining popularity. In this paper, a theory of the fluorescence distribution along with the excitation light path is derived from our previous research about the spatial micro-element method. According to the relationship between the summation of fluorescence intensities along the vertical direction at a certain position on the excitation light path and the position, a high-concentration and wide-range fluorescent substance quantification method based on the IFE and fluorescence imaging analysis is proposed. Correspondingly, a high-throughput fluorescent substance quantification detection system is constructed. In order to validate the method, solutions of rhodamine B in different concentrations are used for principle validation, concentration prediction, and experimental investigation on the influence of integration time and lens distortion. The high-throughput system enables the simultaneous measurement of six samples, realizing the high-concentration and wide-range quantification of rhodamine B (100–600 mg/L) with high precision (R2 = 0.9992, MRE = 2.34 %). By setting the filter wheel, the system can measure the concentration of fluorescent substances with different emission wavelengths. The improvement of experimental device is expected to reduce the single sample capacity to tens of microliters and increase the overall sample quantity to tens or even hundreds. The proposed method and system are beneficial to fluorescence measurement in fields such as biomedicine and dye research and to the improvement of high-throughput fluorescence quantitative PCR instruments.

Postnatal survival of phrenic motor neurons is promoted by BDNF/TrkB.FL signaling.

The number of motor neurons (MNs) declines precipitously during the final trimester before birth. Thereafter, the number of MNs remains relatively stable, with their connections to skeletal muscle dependent on neurotrophins, including brain-derived neurotrophic factor (BDNF) signaling through its high-affinity full-length tropomyosin-related kinase receptor subtype B (TrkB.FL) receptor. As a genetic knockout of BDNF leads to extensive MN loss and postnatal death within 1-2 days after birth, we tested the hypothesis that postnatal inhibition of BDNF/TrkB.FL signaling is important for postnatal phrenic MN (PhMN) survival. In the present study, we used a 1NMPP1-sensitive TrkBF616A mutant mouse to evaluate the effects of inhibition of TrkB kinase activity on phrenic MN (PhMN) numbers and diaphragm muscle (DIAm) fiber cross-sectional area (CSA). Pups were exposed to 1NMPP1 or vehicle (DMSO) from birth to 21 days old (weaning) via the mother's ingestion in the drinking water. Following weaning, the right phrenic nerve was exposed in the neck and the proximal end dipped in a rhodamine solution to retrogradely label PhMNs. After 24 h, the cervical spinal cord and DIAm were excised. Labeled PhMNs were imaged using confocal microscopy, whereas DIAm strips were frozen at ∼1.5× resting length, cryosectioned, and stained with hematoxylin and eosin to assess CSA. We observed an ∼34% reduction in PhMN numbers and increased primary dendrite numbers in 1NMPP1-treated TrkBF616A mice. The distribution of PhMN size (somal surface area) DIAm fiber cross-sectional areas did not differ. We conclude that survival of PhMNs during early postnatal development is sensitive to BDNF/TrkB.FL signaling.NEW & NOTEWORTHY During early postnatal development, BDNF/TrkB signaling promotes PhMN survival. Inhibition of BDNF/TrkB signaling in early postnatal development does not impact PhMN size. Inhibition of BDNF/TrkB signaling in early postnatal development does not impact the number or CSA of DIAm fibers.

Entangled Two-Photon Absorption in Transmission-Based Experiments: Deleterious Effects from Linear Optical Losses.

Recently different experimental schemes have been proposed to study the elusive phenomenon of entangled two-photon absorption (ETPA) in nonlinear materials. The attempts to detect ETPA using transmission-based schemes have led to results whose validity is currently under debate because the ETPA signal can be corrupted or emulated by artifacts associated with linear optical losses. The present work addresses the issue of linear losses and the corresponding artifacts in transmission-based ETPA experiments through a new approach that exploits the properties of a Hong-Ou-Mandel (HOM) interferogram. Here, we analyze solutions of rhodamine B (RhB), commonly used as a model of a nonlinear medium in ETPA studies. Then, by using the HOM interferometer as a sensing device, we first demonstrate the equivalence of the standard transmission vs pump power ETPA experiments, presented in many reports, with our novel approach of transmission vs two-photon temporal delay. Second, a detailed study of the effects of optical losses, unrelated to ETPA, over the HOM interferogram is carried out by: (1) characterizing RhB in solutions prepared with different solvents and (2) considering scattering losses introduced by silica nanoparticles used as a controlled linear loss mechanism. Our results clearly expose the deleterious effects of linear optical losses over the ETPA signal when standard transmission experiments are employed and show how, by using the HOM interferogram as a sensing device, it is possible to detect the presence of such losses. Finally, once we showed that the HOM interferogram discriminates properly linear losses, our study also reveals that under the specific experimental conditions considered here, which are the same as those employed in many reported works, the ETPA was not unequivocally detected.

Enhanced photo-Fenton degradation of dyes under visible light with recyclable γ-Fe2O3/CQDs: Catalyst preparation, performance and mechanism insight

A low band gap and visible light-responsive heterogeneous Photo-Fenton catalyst of γ-Fe2O3/CQDs micron composite was prepared under the one-pot hydrothermal method. The Photo-Fenton degradation of γ-Fe2O3/CQDs towards dye solution of rhodamine B(RhB), methyl blue (MB), and methyl orange (MO) was studied comparatively with α-Fe2O3. The γ-Fe2O3/CQDs exhibited remarkable catalytic performance for various dyes and with a first-order rate (k) of 14 times higher than that of initial α-Fe2O3 with a low concentration of H2O2 of 0.049 mmol. L−1 and a wider pH range of 3.1–7.1. The microstructure of the compounds was observed by XRD, SEM, TEM, FT-IR, and XPS characterization results suggested that the γ-Fe2O3/CQDs nanocomposite was formed through the stable Fe–O–C bonds, thus, the band gap decreased, and it is more favorable for the distance of holes and electrons. The free radical trapping experiment and EPR analysis indicated that •OH and 1O2 were the major active species during the typical photo-Fenton reaction. What's more, the γ-Fe2O3/CQDs also exhibited good stability and magnetic properties. DFT conclusion shows that the mechanism of the potential determination step (PDS) on α-Fe2O3(220) is the cleavage of H2O2 with an energy barrier of only 0.08 eV, which is 0.54 eV lower than that of OH* on γ-Fe2O3(220). Thus it can be deemed that γ-Fe2O3/CQDs perform much higher catalytic activity for the dissociation of H2O2 than α-Fe2O3. This work gives a feasible and economical countermeasure of visible light Photo-Fenton dispose of dye wastewater with a recyclable magnetic γ-Fe2O3/CQDs micron catalyst.

Hydrocarbon-Impacted Soils Supported Mn for Organic Pollutant Oxidation

Hydrocarbon-impeded soil (HIS) is solid waste from spills or leaks during industrial activities that negatively impact the environment. This study aims to utilize HIS as catalyst support on MnO2 to degrade RhB (RhB) solution using Peroxymonosulfate (PMS) and to determine the optimum conditions for the catalyst to degrade RhB. The catalyst was synthesized by reacting HIS, calcined with KMnO4 with various catalyst supports with high and low Total contain Petroleum Hydrocarbon (TPH). The process degradation of Rhodamine Solution was carried out with various catalysts, PMS, and RhB concentrations. The catalyst was characterized using X-ray diffraction (XRD), Nitrogen gas adsorption-desorption (BET), and Scanning Electron Microscope-Energy Disperse Spectroscope (SEM-EDX). In this study, the best catalyst performance was MnO2@H-TPH, which could activate PMS to degrade RhB with dye removal of 98% in about 180 min, at conditions 10 g/L RhB, 0.1 g/L catalyst, and 3 g/L PMS with the activation energy of 16.3 kJ/mol.

DETECTION OF RHODAMINE VIA SURFACE ENHANCED RAMAN SPECTROSCOPY UTILISING AG NANOWIRES

Rhodamine, which is extensively used as a synthetic dye in food industry, is regarded as an illegal additive by European Food Safety Authority because of its carcinogenic and toxicological properties. Since it’s a colourless material at low concentrations such as 10-7 M, its detection via spectroscopical methods is very challenging and crucial in terms of food safety issues. Surface Enhanced Raman Spectroscopy (SERS) provides a fast and cheap method for detection of such molecules at ultra-low concentrations. It is based on the principle of boosting Raman signals, which have low intensity by nature, by utilising metal nanoparticles in order to enhance Raman signals by creating hot-spots. In this study Ag nanowires were synthesized, their crystal structure is characterized via XRD analysis, their surface morphology and radius are determined via SEM images and EDS analysis was performed for determining their chemical composition. Afterwards, rhodamine solutions which were prepared at 10-4 – 10-7 M was dropcasted onto Ag nanowire solutions. After selecting three characteristic Raman peaks belonging to the Rhodamine molecule, which are located at 612, 1189 and 1362 cm-1, detection of Rhodamine was performed at these ultra low concentrations. As a result, one can conclude that, Ag nanowires can be utilized as possible SERS substrates for detection of Rhodamine at low concentrations by exhibiting significant reproducibility, stability and recyclability.

A novel magnetic photocatalyst SnO2/SrFe12O19 applied in degradation for Rhodamine B

A novel photocatalyst SnO2/SrFe12O19 (SS) was fabricated by a two-step hydrothermal method, and was characterized by XRD, SEM, EDS, XPS, BET, UV-Vis DRS. The photocatalytic activity was assessed through degrading solution of Rhodamine B (RhB) under simulated solar irradiation. The results showed that composite of wt 5% SrFe12O19 (SS-5) had superior photocatalytic activity, and the degrading ratio could reach 83.8% within 120 min, which was more than the pure phase SnO2. Moreover, specific surface area, cumulative pore volume, and average adsorption pore size of SS-5 slightly enhanced, the light absorption range expanded to the visible light direction, and the band gap energy decreased. Meanwhile, the VSM test showed that the magnetization saturation of SS-5 was 1.42 emu/g, and magnetic separation could be achieved. In the photocatalytic degradation process, RhB was successfully degraded under the effect of superoxide radical (·O2−), and photogenerated hole (h+). Based on these findings, possible photocatalytic mechanism was investigated and explained. The fabricated SnO2/SrFe12O19 could be used as a valuable photocatalyst for the treatment of sewage.

Comparative Study of Rhodamine B Treatment: Assessing of Efficiency Processes and Ecotoxicity of By-Products

In this work, a comparative study between two processes was performed—biodegradation and photocatalysis, as an advanced oxidation process—to discover which one is more efficient to degrade Rhodamine B, a synthetic dye widely used in the textile and food industries. The advantage of this study is that it correlates treatment efficiency with the ecotoxicity of the by-products resulting from the treatments. Since the COVID-19 pandemic, it has been difficult to use activated sludge because of the risk factor of COVID-19 infection. Therefore, biodegradation tests were conducted with the yeast Saccharomyces cerevisiae in this study. For the photocatalysis assays, TiO2 doped with 5 per cent Cerium was used as a catalyst under UV light irradiation. S. cerevisiae cannot reduce RhB by biodegradation. However, a 13 per cent biosorption was observed with an uptake capacity of 4.2 mg g−1 dry matter of S. cerevisiae cultivated in the presence of 5 mg L−1 of RhB after 150 min. At a 5 mg L−1 of RhB concentration, the 6 h photocatalysis treatment led to 55% color removal and 8.6% COT reduction. The biodegradability of the photocatalyzed solution increased since the BOD5/COD ratio raised from 0.10 to 0.42. In the presence of glucose as a source of carbon, yeast can grow on the by-products generated by photocatalysis. The phytotoxicity of RhB in solution was measured using the germination index (GI) of watercress seeds. The GI decreases by 75% for an RhB solution of 100 mg L−1 compared to the control sample. The by-products of the photocatalytic treatment, using crustaceans Daphnia magna and conducted with solutions of Rhodamine B, induced a decrease of 24% in the GI. Lethality test. After 3 or 6 h of treatment, no increase in immobilization or mortality of D. magna was observed compared to the negative control.

Highly efficient Z-scheme Ag3PO4/PtNPs/g-C3N4 photocatalyst for degradation of organic pollutants in water

Organic pollutants in water cause serious waste of water resources. Therefore, it is important to design efficient photocatalysts to address the problem of waste water. Herein, solid Z-scheme heterojunction photocatalyst, Ag3PO4/PtNPs/g-C3N4, was prepared via in-situ deposition. Under xenon lamp (full wavelength) irradiation, the catalyst efficiently degraded solutions of rhodamine B and phenol within 9 min and 30 min, respectively. This shows better photodegradation performance (99.4% of Rh B, and 97.0% of phenol) than other catalysts and demonstrates that the synergistic effect of its three components results in improved photocatalytic activity. Furthermore, holes and superoxide radicals were identified as main active species during catalysis with Ag3PO4/PtNPs/g-C3N4 based on scavenging experiments of active species and electron spin resonance detection results. In proposed photocatalytic mechanism, PtNPs act as a bridge and accelerate charge transfer on ternary Ag3PO4/PtNPs/g-C3N4. This study provides ternary Z-scheme heterojunction photocatalyst construction for application in the treatment of organic pollutants.

A smart and sustainable pathway for abatement of single and binary mixtures of dyes through magnetically retrievable Ca4Fe9O17 anchored on Biochar matrix

In this work, the author developed Ca4Fe9O17/biochar (CFB) via a green method through a facile co-precipitation procedure involving egg shells as calcium precursor and investigating its performance in single as well as binary solution of methylene blue (MB) and rhodamine B (RhB). The CFB nanocomposite was characterized by XRD, SEM, TEM, XPS, Raman, FTIR, BET, and VSM. ESR studies show the presence of hydroxyl (·OH) and superoxide (O2·¯) radicals, which are primary radical species for pollutant degradation. The average crystalline size of CFB nanocomposites was found to be 32.992 nm using XRD, whereas TEM analysis indicates a particle diameter of 35–36 nm. The degradation efficacy of MB and RhB dyes was achieved at 99.2% and 98.6%, respectively, in a single solution, whereas 99.4% and 99.2%, respectively, in a binary solution within 36 min. Additionally, an iron cluster was formed during the degradation process of MB dye. The degradation of organic contaminants and generation of iron clusters from the degraded dye products were both expedited by the remarkable extension effect of the Ca4Fe9O17 in the CFB nanocomposites. The three processes were achieved using CFB nanocomposite: (1) the advanced oxidation process; (2) degradation of MB and RhB dye in single as well as binary solution with enhanced efficiency, (3) the production of the iron cluster from degraded products. Thus, these three steps constitute a smart and sustainable way that leads to an effective effluent water treatment system and the generation of iron clusters preventing secondary pollution.

Effect of lithium codoping on the structural, morphological and photocatalytic properties of Nd-doped ZnO

Nanostructured ZnONd nanoparticles (NPs) codoped with lithium at low temperature and short synthesis time were prepared using the polyol method, and the influence of different lithium contents at constant atomic concentration of Nd was evaluated. The resulting materials were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller analysis (BET), X-ray photoelectron spectroscopy (XPS), and optical spectroscopies (photoluminescence (PL), cathodoluminescence (CL) and Raman). X-ray diffraction patterns demonstrate that the materials are polycrystalline with a wurtzite structure with no secondary phases in the concentrations evaluated. The unit cell parameters were determined, and the crystallite size was calculated considering the three most intense diffraction peaks. TEM shows that the particles are polycrystalline with no amorphization. Raman analysis further confirms the wurtzite hexagonal structure of the particles. Morphological and size studies using SEM and TEM show that the most remarkable change is the evolution from hemispherical ZnO NPs to spindle-shaped particles for Li–Nd doped ZnO. The surface chemistry, as studied by X-ray photoelectron spectroscopy (XPS), confirms the incorporation of Nd3+. The study of the photocatalytic behavior of the Li–Nd codoped ZnO NPs reveals that the ZNL0.5 sample exhibits the highest photocatalytic activity using a solution of Rhodamine B (2.5 ppm) as a reference.

Quantitative PEEM and Raman Study of Nanorough Au SERS-Active Substrates for Molecular Sensing Applications

Surface-enhanced Raman scattering (SERS) is a well-established surface-sensitive technique for detecting trace amounts of molecular analytes. While the impact of surface singularities on plasmonic materials has been widely studied, the fabrication of cost-effective, efficient SERS substrates remains a challenge. In this paper, we present the study of large-area nanorough Au SERS-active substrates, elaborated by thermal evaporation deposition by photoemission electron microscopy (PEEM), a high-resolution near-field mapping technique, to access the statistical properties of the hot-spot distribution. We experimentally demonstrate that the near-field PEEM and far-field Raman statistical signatures of nanorough Au surfaces are quantitatively correlated when used for molecular sensing. The maximum of the SERS signal of thiophenol (TP) molecules diluted to 10–6 M is observed near the film percolation threshold for which the hot-spot density is maximum. Finally, SERS measurements from solutions of TP, crystal violet, and rhodamine B molecules at 10–8 M demonstrated the sensitivity of our substrates for molecular sensing.

In-silico, in-vitro and ex-vivo evidence of combining silymarin phytopharmaceutical with piperine, and fulvic acid for enhancing its solubility and permeability

Non-alcoholic fatty liver disease is one of the leading causes of death worldwide. Even if with such a high mortality there is no definite treatment approved. Thus, there is a need to develop a formulation which can have multiple pharmacological activities. Herbal drugs are among the most promising compounds that act by different pharmacological actions. For increasing the bio-activity of Silymarin we had isolated five active biomarker molecules from silymarin extract (as a Phytopharmaceutical) in our previous work. It possesses lower bioavailability due to poor solubility, lesser permeability and first pass metabolism effect. Therefore, from the literature we had screened two bioavailability enhancers i.e. piperine and fulvic acid for overcoming the drawbacks associated with silymarin. Hence, in this study we had first explored the ADME-T parameters and then evaluated their in-silico activity for different enzymes involved in inflammation and fibrosis. Interestingly, it was found that besides the bioavailability enhancing property, piperine and fulvic acid also shown anti-inflammatory and anti-fibrotic action, particularly more activity was demonstrated by fulvic acid than piperine. Furthermore, the concentration of the bioavailability enhancers i.e. 20% FA and 10% PIP were optimized by QbD assisted solubility studies. Moreover, the percentage release and apparent permeability coefficient of the optimized formulation was found to be 95% and 90%, respectively as compared to 6.54*106 and 1.63*106 respectively by SM suspension alone. Furthermore, it was found that plain rhodamine solution penetrated only up to 10 um whereas, formulation penetrated up to 30 um. Thus, combining these three, can not only increase the bioavailability of silymarin, but might also, increase the physiological action synergistically.

Photocatalytic Decolourization of Rhodamine B by Modified Photo-Fenton Process with Quasicrystals – Preliminary Research

Abstract A novel photocatalytic process using a modification of photo-Fenton reaction, with sodium percarbonate (SP), as an alternative source of H2O2, and alloy Al65Cu20Fe15 containing, among others, quasicrystals (of the percentage composition Al65Cu20Fe15), being a source of iron ions, effectively decolourizes the aqueous solution of rhodamine B (RB; solution of 5 mg/l). The source of UV radiation was a lamp with a power of 36 W. The experiments were carried out at pH = 7 and reaction time (from 5 to 60 min). The increase in SP concentration (in the range of 8.3 to 33.3 g/l) significantly increased the degree of degradation of RB and the reaction rate. However, the use of quasicrystals, in the range of 8.3 to 33.3 g/l, was also important in the modified photocatalytic photo-Fenton process. The best degradation effects of RB (95%) were obtained for the highest SP concentration of 33.3 g/l and the lowest quasicrystal concentration of 8.3 g/l. On the other hand, visual decolourization of RB was obtained with an efficiency of 70% for SP and quasicrystal concentrations of 16.7 g/l and 16.7 g/l, respectively, after 45 minutes, and for SP and quasicrystal concentrations of 33.3 g/l and 8.3 g/l, respectively, after the time of 20 minutes. The best RB degradation effects in the comparative method (UV/Na2CO3·1.5H2O2 without the addition of quasicrystals) were only 52.7%. The obtained results encourage further research to optimize the conditions of the proposed method and to investigate its applicability to other types of dyes and pollutants.

Spectral Considerations of Entangled Two-Photon Absorption Effects in Hong-Ou-Mandel Interference Experiments.

Recently, different experimental methods intended to detect the entangled two-photon absorption (ETPA) phenomenon in a variety of materials have been reported. The present work explores a different approach in which the ETPA process is studied based on the changes induced in the visibility of a Hong-Ou-Mandel (HOM) interferogram. By using an organic solution of Rhodamine B as a model of nonlinear material interacting with entangled photons at ∼800 nm region produced by spontaneous parametric down-conversion (SPDC) Type-II, the conditions that make possible to detect changes in the visibility of a HOM interferogram upon ETPA are investigated. We support the discussion of our results by presenting a model in which the sample is considered as a spectral filtering function which fulfills the energy conservation conditions required by ETPA, allowing us to explain the experimental observations with good agreement. We believe that this work represents a new perspective to studying the ETPA interaction, by using an ultrasensitive quantum interference technique and a detailed mathematical model of the process.

Ch][TAPSO] As an Efficient Ionic Liquid Catalyst for One‐Pot Synthesis ofTetrahydro‐4H‐chromenes and 3,4‐Dihydropyrano[c]chromenes

AbstractCholinium N‐Tris(hydroxymethyl)methyl‐3‐amino‐2‐hydroxypropanesulfonate [Ch][TAPSO] has been found as an efficient ionic liquid catalyst for the synthesis of tetrahydro‐4H‐chromenes and 3,4‐dihydropyrano[c]chromenes in water and EtOH : Water (3 : 2) respectively. [Ch][TAPSO] being a basic IL has also been observed to extract acidic compounds such as rhodamine B from IL‐ immiscible organic solvent such as acetone through acid‐base interaction. The extraction process of fluorescent dye rhodamine B was determined by ultraviolet‐visible (UV‐Vis) spectroscopy. The observed percentage extraction rate is 100 % upto 6 mM solution of rhodamine in acetone. This method results in faster reaction with operational simplicity and excellent yields of the products. Furthermore, the catalyst has a great capacity for reutilisation.

A 3D oxalate‐bridged [CuIIFeII] coordination polymer as molecular precursor for CuFe2O4 spinel—photocatalytic features

AbstractA 3D heterometallic oxalate‐bridged coordination polymer [CuIIFeII2(H2O)(terpy)(C2O4)3]n (terpy = 2,2′:6′,2″‐terpyridine) (1) was investigated both as photocatalyst for the organic dye removal and as a single‐source precursor for the preparation of the copper ferrite (CuFe2O4) nanocrystals by thermal processing. The dual functionality of 1 was supported by the degradation of aqueous solutions of rhodamine B (RhB) and methylene blue (MB) solutions under visible (Vis) and ultraviolet (UV) light irradiation, powder X‐ray diffraction data collection at room temperature, and the optical and scanning electron microscopy analyses. A close inspection of the X‐ray diffraction patterns unveiled qualitative and quantitative information on the phase composition obtained after the single‐source molecular precursor route to spinel oxide. By optimizing the temperature levels and setting the controlled heating rate at 6 h of holding time, the phase composition of thermal processing of 1 was evaluated—thermal treatment of 1 at 950°C for 6 h and a heating/cooling rate of 10°C min−1 resulted in the formation of solely tetragonal spinel phase of CuFe2O4, whereas the formation of both tetragonal and cubic CuFe2O4 phases was observed at 950°C by the heating rate of 30°C min−1. To obtain the high‐temperature cubic CuFe2O4 oxide, compound 1 was heated and then quenched at 925°C, which led to the formation of the cubic spinel ferrite as the main crystalline oxide phase. Moreover, the photocatalytic properties of the t‐CuFe2O4 spinel were investigated under the same conditions as for 1. The optical bandgap energies were estimated from UV–Vis absorption spectra for both metal oxide and precursor powder.

Combining physical vapor deposition structuration with dealloying for the creation of a highly efficient SERS platform.

Nanostructured noble metal thin films are highly studied for their interesting plasmonic properties. The latter can be effectively used for the detection of small and highly diluted molecules by the surface-enhanced Raman scattering (SERS) effect. Regardless of impressive detection limits achieved, synthesis complexity and the high cost of gold restrict its use in devices. Here, we report on a novel two-step approach that combines the deposition of a silver-aluminum thin film with dealloying to design and fabricate efficient SERS platforms. The magnetron sputtering technique was used for the deposition of the alloy thin film to be dealloyed. After dealloying, the resulting silver nanoporous structures revealed two degrees of porosity: macroporosity, associated to the initial alloy morphology, and nanoporosity, related to the dealloying step. The resulting nanoporous columnar structure was finely optimized by tuning deposition (i.e., the alloy chemical composition) and dealloying (i.e., dealloying media) parameters to reach the best SERS properties. These are reported for samples dealloyed in HCl and with 30 atom % of silver at the initial state with a detection limit down to 10-10 mol·L-1 for a solution of rhodamine B.