Rhodamine B Research Articles

A Dual Emission Fluorescence Probe Based on Silicon Nanoparticles and Rhodamine B for Ratiometric Detection of Kaempferol.

In this paper, blue fluorescent silicon nanoparticles (SiNPs) with outstanding optical properties and robust stability were synthesized by a simple one-step hydrothermal method. By introducing red emissive rhodamine B (RhB) into SiNPs solution, a dual emission nanoprobe (SiNPs@RhB) was constructed, which showed excellent pH stability, salt resistance and photobleaching resistance. The SiNPs@RhB probe could emit two peaks at 444nm and 583nm under 365nm excitation. It was found that the fluorescence intensity of the two emission peaks decreased in different degrees with the addition of different concentrations of kaempferol (Kae). According to this phenomenon, a novel ratiometric fluorescence method was established for the detection of Kae via utilizing SiNPs@RhB as nanoprobe. The detection range and limit of detection (LOD) were 0.5 ~ 150 µM and 0.24 µM, respectively. The ratiometric fluorescence method exhibited the superiority of rapid detection, excellent stability, wide linear range and high sensitivity. The detection mechanism was studied by ultraviolet visible absorption spectra, fluorescence spectra and fluorescence lifetime. Furthermore, the method was applied to the detection of Kae in real samples (kaempferia powder, sea buckthorn granules and sea buckthorn dry emulsion).

A highly efficient and stable PtNi bimetallic nanoparticles modified on Mo2C decorated N-doped carbon flowers catalysts for the remediation of environmental pollutants

The unregulated discharge of nitroaromatics (NAs) and organic dye contaminants into aquatic ecosystems is a growing global concern, highlighting the urgent need for the development of effective wastewater treatment technology. In this study, we prepared Mo2C decorated on N- doped carbon flowers supported with PtNi bimetallic (PtxNiy@Mo2C/NCF) nanoparticles using the self-polymerization of dopamine and followed by the chemical reduction methods. These catalysts, with varying Pt:Ni ratios, were designed for the highly efficient catalytic reduction of NAs and rhodamine b (RhB) under the mild reaction conditions. The HR-TEM images confirmed the formation of spherical PtNi bimetallic NPs with an average diameter of 1.68 ± 0.6 nm. The prepared PtxNiy@Mo2C/NCF catalysts exhibited significantly higher catalytic efficiency for 4-nitrophenol (4-NP) reduction compared to their respective monometallic counterparts using NaBH4. Particularly, the Pt0.75Ni0.25@Mo2C/NCF catalyst showed superior catalytic activity with the apparent rate constant (kapp: 0.6703 min−1) and TOF (17.0 × 10−7 mol mg−1 min−1) and high recyclability over eight consecutive recycles. Furthermore, the Pt0.75Ni0.25@Mo2C/NCF catalyst also exhibited high catalytic activity for other NAs and RhB dye reduction with excellent yields. This enhanced catalytic activity of Pt0.75Ni0.25@Mo2C/NCF catalyst could be ascribed to the synergistic effect of the bimetallic systems, leading to more efficient reactions. Additional experiments were conducted on a fixed bed reactor to demonstrate that the Pt0.75Ni0.25@Mo2C/NCF catalyst effectively reduce both 4-NP and RhB dye over 15 successive runs. This work may pave the way for using PtxNiy@Mo2C/NCF catalysts in various wastewater treatment applications.

Visible light-improved periodate activation of natural chalcopyrite particles towards effective pollutants degradation

The aim of this paper is to build an efficient and low-cost advanced oxidation system to realize the antibiotic wastewater purification which has a realistic significance. In this study, a system of visible light-assisted activation of natural chalcopyrite to activate periodate was adopted to remove tetracycline (TC). The results demonstrated that the removal efficiency (100% within 60 min) of TC in the CuFeS2/PI/Light system was significantly improved compared to the CuFeS2/PI system or PI process alone, and the degradation rates of TC in the CuFeS2/PI/Light system were 5.9 times higher than that of the CuFeS2/PI system, which is attributed to the synergistic effect of light and PI activation. The system also effectively degraded sodium butyl xanthate (SBX), chlortetracycline hydrochloride (CTC) and Rhodamine B (RhB), while the efficiency of the degradation process was further enhanced in natural water quality. The active substance quenching experiment revealed that [Formula: see text]OH, 1O2, O2[Formula: see text], IO4[Formula: see text] and IO3[Formula: see text] were the main substances to achieve effective TC removal. In addition, the cycling of Cu[Formula: see text]/Cu[Formula: see text] and Fe[Formula: see text]/Fe[Formula: see text] present in chalcopyrite improved the activation of PI. Further, visible light is conducive to the valence cycling of Cu and Fe, as well as the production of more oxidizing free radicals, thus achieving the synergy of photocatalysis and PI activation. This study provides a low-cost and efficient advanced oxidation pathway for the removal of antibiotic wastewater.

High-efficient separation of photoinduced charge carriers in CoFe2O4-ZnO magnetic heterostructures mediated by oxygen vacancies

In this work, magnetic heterostructures were obtained by the in-situ growth of various ZnO amounts on the preformed CoFe2O4 nanoparticles. The X-ray diffraction characterization shows the presence of both ZnO and CoFe2O4 crystalline phases, and the crystallite size is about 13–14 nm for both components. X-Ray Photoelectron Spectroscopy (XPS) analysis revealed a CoFe2O4 inversion degree of 0.7. The composite samples demonstrated an extended absorption edge into the visible range. The sample’s magnetic properties were investigated by vibrating-sample magnetometer (VSM) and correlated with Electron Paramagnetic Resonance (EPR) results. The magnetic behavior was attributed to the combination of CoFe2O4 and ferromagnetic ZnO. The emergence of a ferromagnetic phase within ZnO was elucidated to originate from charge/spin transfer of spin-up polarized states from the CoFe2O4 Fermi level into empty oxygen vacancies of ZnO. High efficiency in Rhodamine B (RhB) degradation under visible light was observed in the prepared composite materials, particularly with an optimal CoFe2O4-ZnO ratio of 1:5, achieving an 81 % degradation rate within 6 h. The proposed photodegradation mechanism, based on various spectroscopic and magnetic investigations, highlights the role of spin transfer and oxygen vacancies in facilitating reactive oxygen species (ROS) generation for pollutant degradation.

Enhanced photocatalytic degradation of organic pollutants via black phosphorus-mediated electron transfer in g-C3N4/BiOI: Degradation mechanisms and biotoxicity assessment

Photocatalysis is a promising strategy for organic pollutant removal, yet developing a capable photocatalyst remains challenging. Using black phosphorus (BP) as an electron buffer material, the ternary composite photocatalysts of xBP/g-C3N4/BiOI were prepared through a straightforward hydrothermal method. Tetracycline (TC) and Rhodamine B (RhB) removals were 100 % (120 min) and 99 % (90 min) by photocatalytic process on 2.5 %BP/g-C3N4/BiOI under xenon lamp irradiation. Photoluminescence and electrochemical measurements confirmed BP's role in reducing charge transfer barriers between g-C3N4 and BiOI, achieving effective separation of photogenerated electrons. The degradation mechanisms of TC and RhB on 2.5 %BP/g-C3N4/BiOI were revealed by the quenching experiments, electron paramagnetic resonance spectroscopy tests, three-dimensional excitation-emission matrix fluorescence spectrum, and liquid chromatography-mass spectrometry analyses. Plant toxicity assessment experiments confirmed the non-toxic nature of the TC and RhB degradation solutions. Plants grown in the treated solutions exhibited declining trends in both Malondialdehyde and Peroxidase indices compared to untreated solutions. This study offers a fresh approach to advanced photocatalyst design using charge transfer buffer materials.

Photocatalytic degradation of rhodamine B dye pollutants by Fe3O4/SiO2 core-shell magnetic nanocomposite functionalized with TiO2.

Significant efforts have been dedicated to creating recyclable and efficient methods for treating waste dyes, including rhodamine B (RhB). Nevertheless, challenges such as complex operational techniques, high costs, energy consumption, and inefficacy in dye removal persist. Here, the synthesis and application of TiO2/Fe3O4/SiO2 for photocatalytic degradation of RhB dye pollutants have been explored. This research was initiated with magnetite (Fe3O4) synthesis using the coprecipitation method, followed by silica (SiO2) extraction from rice husk waste using the sol-gel process, and a hydrothermal method for synthesizing titanium dioxide (TiO2) and TiO2/Fe3O4/SiO2 nanocomposite. The crystalline structure of TiO2/Fe3O4/SiO2 was obtained with Fe3O4 as the core, while TiO2 and SiO2 as the shell. The particle size analysis showed the nanosize of TiO2/Fe3O4/SiO2 (1.04 ± 0.46nm). TiO2/Fe3O4/SiO2 nanocomposite boasts a high surface area of 48.025 m2/g, 2.2 times higher than unmodified TiO2. This nanocomposite also displayed paramagnetic properties with a saturation magnetization of 9.117emu/g, facilitating easy separation in photocatalytic applications. The photocatalytic activity of TiO2/Fe3O4/SiO2 exhibited effectively degraded RhB, achieving a degradation rate of 53.58% and an excellent rate constant of 0.7303min-1. The RhB photodegradation in this study requires a moderate irradiation time (60min), uses only a tiny amount of photocatalyst (100mg), and does not need additional chemicals. Moreover, this study has another advantage of utilizing rice husk as a silica source, offering an eco-friendly and sustainable approach.

Boosting the piezocatalytic performance of BaTiO3-based materials via phase boundary and defect co-engineering

Recently, piezocatalytic technology has been recognized as an efficient and viable strategy for the remediation of aquatic environments. Herein, a synergistic strategy of phase boundary and defect co-engineering has been proposed to enhance the piezocatalytic performance of BaTiO3-based ceramic materials: a ceramic system material ((1-x)BaTiO3-x(Ca0.9Sr0.1)(Sn0.5Hf0.5)O3, (1-x)BT-xCSSH) was constructed to achieve the coexistence of multiple ferroelectric phases by co-doping ions in the A/B-sites, and defect engineering was realized by a high-temperature annealing. The 0.95BT-0.05CSSH ceramic exhibits the coexistence of rhombic (R), orthorhombic (O), and tetragonal (T) phases, with multiple spontaneous polarization directions and low polarization rotational energy barriers, thereby demonstrating high piezoelectricity (d33 = 450 pC/N) and thus outstanding piezocatalytic performance. The degradation rate/reaction rate constant of the 0.95BT-0.05CSSH ceramic material for rhodamine B (RhB) is 71.35 %/13.5 × 10−3 min−1. After undergoing a high-temperature annealing, the catalytic activity of the 0.95BT-0.05CSSH ceramic is further improved, resulting in a degradation rate/reaction rate constant of 92.84 %/28.5 × 10−3 min−1 for rhodamine B (RhB). The catalytic activity of the 0.95BT-0.05CSSH material is enhanced by the generation of abundant oxygen vacancies during high-temperature annealing, which facilitates the separation and migration of electron-hole pairs. In this study, we propose a novel strategy to upgrade the piezocatalytic performance of BaTiO3-based piezoelectric materials, which is useful for the remediation of aquatic environments.

Degradation of organic pollutants in natural magnetite-activated peroxymonosulfate system enhanced by hydroxylamine: Catalytic performance, reaction pathway, and enhancement mechanism

The degradation of organic pollutants using natural minerals in advanced oxidation process gains increasing interest due to abundant resources, rich active metals, and easy engineered preparation, but it is limited by the relatively low catalytic performance of natural minerals. The enhanced pollutant degradation in natural mineral/peroxymonosulfate (PMS) system has been rarely studied. In this work, the enhancement of hydroxylamine natural magnetite/PMS system was innovatively proposed. In comparison with the natural magnetite/PMS system, the degradation efficiency of Rhodamine B (RhB) was increased by 61.82 % after the addition of hydroxylamine, and the RhB degradation followed a pseudo-first-order kinetic model with a rate constant of 0.1040 min−1. The Fe2+/Fe3+ conversion efficiency was improved by the synergistic effect of hydroxylamine, which was demonstrated by X-ray photoelectron spectroscopy and determination of the Fe2+ concentration in the reaction system. The influence of process factors on the degradation process was examined, including hydroxylamine concentration, catalyst dosage, PMS concentration, initial pH, temperature, inorganic anions, and humic acid. The hydroxylamine-assisted natural magnetite/PMS system exhibited a wider pH range (3−11) and good reusability (degradation efficiency of 90.30 % for the seventh run). Besides, the effective degradation of different organic pollutants was obtained, including methyl organic, malachite green, tetracycline, sulfadiazine, and ofloxacin. Sulfate radical, hydroxyl radical, and singlet oxygen were mainly reactive oxygen species in the reaction system. The energy consumption was only 4.33 kWh/kg, significantly lower than previously reported systems, showing a significant environmental application value.

Surprising Effects of Al2O3 Coating on Tribocatalytic Degradation of Organic Dyes by CdS Nanoparticles

With a band gap of 2.4 eV, CdS has been extensively explored for photocatalytic applications under visible light irradiation. In this study, CdS nanoparticles have been investigated for the tribocatalytic degradation of concentrated Rhodamine B (RhB) and methyl orange (MO) solutions. For CdS nanoparticles in a glass beaker, 78.9% of 50 mg/L RhB and 69.8% of 20 mg/L MO solutions were degraded after 8 h and 24 h of magnetic stirring using Teflon magnetic rotary disks, respectively. While for CdS nanoparticles in a beaker with Al2O3 coated on its bottom, 99.8% of the RhB solution was degraded after 8 h of magnetic stirring and 95.6% of the MO solution was degraded after 12 h of magnetic stirring. Moreover, another contrast was observed between the two beaker bottoms—a new peak at 250 nm in UV–visible absorption spectra was only observed for the MO degradation by CdS in the as-received glass beaker, which indicates that MO molecules were only broken into smaller organic molecules in that case. These findings are meaningful for expanding the catalytic applications of CdS and for achieving a better understanding of tribocatalysis as well.

(Ce, Nd) co-doped TiO2 NPs via hydrothermal route:Structural, optical, photocatalytic and thermal behavior

Rare earth (Ce, Nd) doped/co-doped titania (TiO2) nanoparticles were successfully produced by hydrothermal route. Titanium isopropoxide (IV), cerium nitrate hexahydrate and neodymium nitrate hexahydrate were utilized as raw/starting materials. The effect of Ce and Nd doping/co-doping in TiO2 were studied through different complementary tools such as XRD, FTIR, FE-SEM, EDX, XPS, UV–Visible, PL, photocatalytic and thermal analysis. XRD spectra revealed anatase tetragonal phase and cubic phase due to titania and ceria nanoparticles respectively. The crystallite size, lattice constants, volume and no. of unit cell were determined through XRD data. Optical studies revealed the band gap, urbach energy, extinction coefficient, refractive index, optical conductivity and photoluminescence emission wavelength. FTIR spectra investigated the chemical bondings and functional groups present in prepared samples. Optical absorption spectra confirmed that absorption edge is red shifted, indicating a decrease in band gap from 3.5 to 3.0 eV with the incorporation of rare earth ions (Ce, Nd) in TiO2 matrix. The rate of electron-hole pair recombination was reduced through co-doping of (Ce, Nd) in TiO2 lattice as exhibited by reduction in intensity of photo luminescence spectra. The photocatalytic efficiency was enhanced with the integration of rare earth metal ions in TiO2 matrix for different dyes such as rhodamine B (RhB) and malachite green (MG) with visible light irradiation. The degradation efficiency of (Ce, Nd) co-doped TiO2 NPs against RhB and MG dyes was found to be 89 and 95 % respectively. TGA analysis was carried out to find weight loss during different thermodynamic phases such as dehydration, decomposition and combustion, and crystallization. Various thermodynamic parameters such as activation energy, entropy and enthalpy were estimated by thermal analysis.

Plant-based synthesis of Selenium-doped Silver/Magnesium Oxide/Zinc Oxide nanocomposite using Mentha pulegium to investigate their photocatalytic and biological properties

In this study, the photocatalytic test and biological effects of Selenium-doped Silver/ Magnesium Oxide/ Zinc Oxide nanocomposite (Se-doped Ag/MgO/ZnO) have been studied. The samples were synthesized by a green method with Mentha pulegium plant extract and investigated by different analyses. The outcomes of X-ray and FESEM display crystal nature and flower-like morphology. According to the ICP results, the removal efficiency of Pb+2 ions was equal to 72 %. The photocatalytic test of the nanocomposite investigated to degradation of organic dyes, and the results show that the degradation percentage of RhB (Rhodamine B), EBT (Eriochrome Black T), MO (Methyl Orange), and MB (Methylene Blue) dyes were about 73 %, 96 %, 99 %, and 97 % respectively. Also, the toxicity of the Se-doped Ag/MgO/ZnO) was studied against the cancer B16F0 cell line and the IC50 value was reported as 269.6 μg/mL.

Localization and Orientation of Dye Molecules at the Surface of a Levitated Microdroplet in Air Revealed by Whispering Gallery Mode Resonances.

Microdroplets offer unique environments that accelerate chemical reactions; however, the mechanisms behind these processes remain debated. The localization and orientation of solute molecules near the droplet surface have been proposed as factors for this acceleration. Since significant reaction acceleration has been observed for electrospray- and sonic-spray-generated aerosol droplets, the analysis of microdroplets in air has become essential. Here, we utilized whispering gallery mode (WGM) resonances to investigate the localization and orientation of dissolved rhodamine B (RhB) in a levitated microdroplet (∼3 μm in diameter) in air. Fluorescence enhancement upon resonance with the WGMs revealed the localization and orientation of RhB near the droplet surface. Numerical modeling using Mie theory quantified the RhB orientation at 68° to the surface normal, with a small fraction randomly oriented inside the droplet. Additionally, low RhB concentrations increased surface localization. These results support the significance of surface reactions in the acceleration of microdroplet reactions.

Novel S-scheme β-Cu2V2O7/Ni/Pg-C3N4 heterojunction photocatalyst for sunlight-induced degradation of RhB

A novel S-scheme β-Cu2V2O7/Ni/Pg-C3N4 nanocomposite photocatalyst has been advantageously established by propelling β-Cu2V2O7 nanoparticles (NPs) on the top layer of porous graphitic carbon nitride (Pg-C3N4) nanosheets (NSs) using a facile co-precipitation approach. Implementing photoelectrochemical and physicochemical techniques, the crystallinity, purity, optical quality, morphology, chemical composition, and charge separation efficiency of the produced samples were examined. The outcomes indicate that metallic Ni and β-Cu2V2O7 NPs were perfectly encapsulated onto the Pg-C3N4 NSs and well-matched band structures between both semiconductors facilitate the creation of an S-scheme charge transfer path. The fabricated pristine and β-Cu2V2O7/Ni/Pg-C3N4 composite samples were utilized as a catalyst for the removal of rhodamine B (RhB) dye under sunlight irradiation. The β-Cu2V2O7/Ni/Pg-C3N4 nanocomposite exhibits exceptional activity within 60 min of radiation exposure (RhB- 98.56%), whereas β-Cu2V2O7 and Pg-C3N4 show reduced activity (RhB-34.4% and 45.68%). The favourable impact of S-scheme nanocomposite establishment boosted photocatalytic behavior using the intrinsic electric field among Pg-C3N4 NSs and β-Cu2V2O7 and surface plasmon resonance (SPR) effect of metallic Nickel (Ni) NPs for delivering e− and h+ pairs and prolonging the life of charge carriers. According to radical scavenging experiments •O2− is the primary reactive species followed by •OH radicals. The produced nanocomposite has the potential to be employed in large-scale photocatalytic water treatment, as evidenced by the photocatalyst's excellent efficiency and reusability after five consecutive experiments.

Facile fabrication of carbon nanotubes/zinc oxide decorated poly(vinyl alcohol) electrospun nanofiber membrane and its photocatalytic performance

AbstractThe carbon nanotubes/zinc oxide (CNTs/ZnO) nanocomposites were immobilized on the poly(vinyl alcohol) (PVA) membrane for highly reutilization rate in photocatalytic degradation of RhodamineB (RhB) based on the combination of electrospinning and ultrasonication treatment. The results revealed that the CNTs are successfully compounded with ZnO, and the surface of nanofibers was uniformly covered with CNTs/ZnO nanoparticles. Under visible light irradiation, the CNTs/ZnO@PVA nanocomposites displayed excellent photocatalytic activity with 98.4% of RhB degradation rate within 3 h illumination. In comparison with pure PVA, and CNTs/ZnO with equivalent loading capacity on CNTs/ZnO@PVA film suspended in aqueous solution, the synthesized CNTs/ZnO@PVA film degrades RhB dye more efficiently. Furthermore, the photocatalytic activity of CNTs/ZnO@PVA nanocomposites did not change significantly even after five recycles, indicating a certain degree of reusability. The mechanism of enhanced photocatalytic activity was proposed. The as‐prepared flexible CNTs/ZnO@PVA nanocomposites could be employed as a promising material for the practical photocatalytic degradation of wastewater.

Enhancement of growth perfection and optical transmission in rhodamine B-doped KDP single crystal for photonic applications

In recent years, because of the rapid development persisting in the modern electronic industries, materials with the ability to produce highly efficient harmonic generation have acquired great demand as they are suitable for high-speed devices and the progressing field of optical communication systems. The present work reports the growth, diffraction and spectroscopic features of the pure and Rhodamine B (RB)-doped potassium dihydrogen phosphate (KDP) crystals. The crystals were grown by employing the conventional slow evaporation technique. The XRD and UV–visible spectral studies have been carried out to examine the structural and optical behavior of the grown crystals. An optical microscopic technique has been utilized to explore the surface features of the crystals. Based on the growth features and the observed analytical results, it is authenticated that the RB-doped KDP crystal possesses a better crystalline nature and optical transmittance than the pure KDP crystal thereby it is strongly suggested for the applications of photonic devices.

Ag nanoparticle functionalized vertical WS2 nanoflakes as SERS substrate for chemical sensing

Two-dimensional transition metal dichalcogenides (TMDCs) present a unique opportunity as Surface Enhanced Raman Scattering (SERS) substrates due to their superior optical properties. Here, vertically oriented tungsten disulfide (WS₂) flakes were synthesized on a silicon (Si) substrate using the pulsed laser deposition (PLD) technique. The WS₂ flakes were employed as SERS substrates for detecting low concentrations of environmental pollutants, like Rhodamine B (RhB) and Methyl Orange (MO) dyes, achieving promising enhancement factors of approximately 10⁷ with a 532 nm excitation laser. To further enhance the plasmonic activity of the vertical WS₂ flakes, silver nanoparticles (NPs) were decorated on their surface via thermal evaporation. The Ag NP-functionalized WS₂ flakes exhibited superior detection capabilities compared to pristine WS₂ flakes, achieving remarkable sensitivity at ultralow concentrations of 10⁻¹⁶ M for RhB and 10–17 M for MO dye, with enhancement factors of the order of 10⁸. The SERS performance of the WS₂-Ag substrate was also evaluated using a 633 nm laser, successfully detecting Methylene Blue (MB) dye at an ultralow concentration of 10⁻¹³ M. Prolonged exposure to RhB, MO, and MB dyes can cause cancer, neurotoxicity, and respiratory irritation. Thus, sensitive detection of these dyes at ultralow concentrations is highly crucial. A charge transfer mechanism between WS₂ and RhB dye molecules is proposed, along with the contribution of Ag NPs, to explain the enhanced detection capabilities of the nanocomposite SERS substrate.

Strongly tribocatalytic dye degradation of high-entropy powder through harvesting friction

The omnipresent friction can be harvested to generate electricity, thereby facilitating redox reactions to degrade dye wastewater, which can be named as tribocatalysis. Here, it’s experimentally found that the high-entropy CoCrFeMnNi powder synthesized via the Vacuum Induction Gas Atomization (VIGA) technique, can behave the obvious tribocatalytic Rhodamine B (RhB) dye degradation performance. In the tribocatalysis dye degradation process, friction occurs at the interface between the catalyst’s surface and the stirring Teflon rod. The tribocatalytic RhB dye degradation ratios of the high-entropy CoCrFeMnNi powder catalysts at stirring speeds of 200 rpm, 400 rpm, 800 rpm, 1000 rpm, and 1200 rpm are 14.7 %, 70.3 %, 93.2 %, 99.4 %, and 99.8 %, respectively. It’s also found that the RhB dye degradation ratio can be slightly enhanced under an external DC magnetic field provided by a commercial NdFeB magnet, which may be attributed to the magnetically-induced enhancement of separation efficiency of these positive and negative carriers. After being recycled for 3 times, the CoCrFeMnNi powder can still degrade 90.8 % RhB dye. The CoCrFeMnNi powder with the excellent tribocatalytic activity is potential for application in dye wastewater treatment through utilizing the friction energy in the environment.

Acid Mediated In‐Situ Catalytic Cleavage/Making of C=N Bonds in Bis‐Hydrazone Uranyl Complexes: Exploration of Photophysical, Electrochemical, Dye Sorption Properties and DFT Studies

AbstractTwo new uranium complexes [UO2L2(H2O)] (where L2=diacetyl bis‐isonicotinoyl hydrazone) complex 1, and [UO2(L1)2] (where L1=diacetylmonoxime isonicotinoylhydrazone) complex 2, have been synthesized by precisely adjusting the pH values of the reaction system. Complex 1 was formed in an acidic ethanolic solution (pH=3) through an in‐situ acid catalytic reaction of diacetylmonoxime isonicotinoylhydrazone and UO2(NO3)2.6H2O, while complex 2 was acquired in a neutral medium (pH=7) through self‐assembly of two ligands and one uranium (VI) metal centre. Both complexes were thoroughly characterized by elemental analysis, UV‐Visible spectroscopy, IR spectroscopy, NMR, TGA, cyclic voltammetry, and powder X‐ray diffraction. The studies indicate that the bis‐hydrazone in complex 1 is a dianionic tetradentate N2O2 donor, whereas in complex 2 it is a monoanionic tridendate N2O donor. The formation of complex 1 was further confirmed by a single‐crystal X‐ray diffraction study, which revealed the role of a water molecule in forming a pentagonal bipyramidal geometry of [UO2L2(H2O)]. Photophysical studies revealed that complexes 1 and 2 exhibited low band gap values of 2.07 and 2.12 eV, respectively, indicating their semiconducting nature. From the CV measurements, the higher negative potentials of the complexes 1 & 2 {1, −0.6 V and 2, −0.5 V vs. ferrocenium/ferrocene (Fc+/Fc)} in DMSO are assigned to the presence of {UO2}2+/{UO2}+ couple signifying their redox active nature. Dye adsorption studies show that both the complexes were able to remove 90 % of Methylene blue (MB) and Rhodamine B (RhB) from the solutions with the concentration of 10−5 M. The structural insights and electronic properties of Ligand HL1 and complex 1 were further explored by density functional theory (DFT) calculations.

Enhanced Photocatalytic Degradation of Organic Dyes by Cerium‐Doped Zinc Oxide Nanocones

AbstractCerium‐doped zinc oxide (Ce‐ZnO) nanocones with cerium concentrations of 0, 0.5, 1, and 2 % were synthesized using a sol‐gel method. Their effectiveness as photocatalysts for degrading dyes such as Rhodamine B (RhB), Methylene Orange (MO), and Methylene Violet (MV) was evaluated. The optical and structural properties, particle size distribution, and morphology of these nanocones were examined using X‐ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet‐visible (UV‐Vis) spectrophotometry. XRD results confirmed that the nanocones were highly crystalline with a hexagonal wurtzite structure, and a noticeable blue shift was observed in the Ce‐doped ZnO nanocones compared to pure ZnO. The photocatalytic performance under UV exposure showed that cerium doping significantly improved the degradation of RhB, MO, and MV. Notably, ZnO nanocones doped with 1 % cerium exhibited the highest photocatalytic efficiency, achieving 100 % degradation of RhB within 60 minutes. Additionally, 1 % Ce‐ZnO nanocones demonstrated degradation efficiencies of 86.3 % for MO and 74.9 % for MV within the same time frame.

Effect of NiAl alloy microparticles deposited in flexible SERS substrates on the limit of detection of rhodamine B molecules.

Flexible-SERS (FSERS) substrates were fabricated by depositing Ni64Al36(NiAl)-alloy-microparticles and/or spherical Ag-NPs (sizes of 10-40 nm) on recycled plastics, which had an aluminum layer on their surface. First, FSERS substrates made of Al + Ag-NPs and an area of 1 cm2 were used to detect rhodamine B (RhB) molecules. The limit-of-detection (LOD) for RhB was 8.35 × 10-22 moles (∼503 molecules), and the enhancement factor (EF) was 3.11 × 1015. After adding NiAl-microparticles to the substrate, the LOD decreased to 8.35 × 10-24 moles (∼5 molecules) and the EF was increased to 2.05 × 1017. Such EF values were calculated with respect to substrates made only with Al + NiAl-alloy (without Ag-NPs), which did not show any Raman signal. Other FSERS substrates were made with graphene-layer + Ag-NPs or graphene-layer + NiAl-alloy + Ag-Nps, and the best LOD and EF values were 8.35 × 10-22 moles and 6.89 × 1015, respectively. Overall, combining the Ag-NPs and NiAl-alloy microparticles allowed for the zeptomole detection of RhB. This was possible due to the formation of Ag aggregates around the alloy microparticles, which enhanced the number of hotspots. If no alloy is present in the FSERS substrates, the detection of RhB is lowered. Overall, we presented a low-cost FSERS substrate that does not require expensive Au films or Au-NPs (as previously reported) to detect RhB at the zeptomole level.