Conventional Hydrothermal Route Research Articles

Development of novel Ce doped ZnO/graphene based sensor for electrochemical investigation of potassium-competitive acid blocker: Vonoprazan

The present study reports the synthesis of a Ce-doped ZnO/r-GO nanocomposite via a conventional hydrothermal route. The synthesized nanocomposites were utilized for the purpose of sensitive and selective detection of vonoprazan (VPN). The composite’s morphological, structural, and electrochemical properties were thoroughly characterized. This study focuses on the utilization of a glassy carbon electrode that has been modified with Ce-doped ZnO/r-GO for the purpose of detecting the potassium-competitive acid blocker VPN, which is commonly used in the treatment of peptic ulcer. The detection methods employed in this study include voltammetric and square wave techniques. The composite material exhibited exceptional efficacy as an electron (e−) transfer mediator during the oxidation of VPN. The modified electrode exhibited a discernible reaction for SWV assessments in relation to VPN identification, achieving a minimal detection threshold of 1.8 × 10−8M and an extensive range of linearity spanning from 2.0 × 10−7 M to 8.0 × 10−6 M, given ideal circumstances. The rate constant for charge transfer (ks) was determined to be 1.17 × 10−6 cm s−1, and an estimation of the electrochemical active surface area yielded a value of 0.081 cm2. The sensor that was artificially created demonstrated favorable selectivity, enduring stability, and notable reproducibility. The sensor has been utilized for the purpose of analyzing human serum and urine samples, yielding favorable recovery outcomes.

Erythritol assisted facile green synthesis of bismuth-rich photocatalyst Bi7O9I3 with enhanced photocatalytic degradation performance

In this work, Bi7O9I3 with efficient photodegradation performance was facilely and greenly synthesized by the synergistic effect of erythritol and sodium hydroxide at room temperature and atmospheric pressure, where erythritol was first used to produce bismuth-rich photocatalysts. This novel synthetic route has several outstanding features such as green chemistry, high yield, mild conditions, high efficiency, use of simple equipment and inexpensive raw materials. The structural, morphological, optical and photoelectrochemical properties of as-synthesized samples were investigated by XRD, XPS, FT-IR, TEM, UV–vis DRS, BET, PL, EIS and PC analysis. The optimal Bi7O9I3-0.1 photocatalyst achieved 97.6% degradation efficiency of 20 mg/L bisphenol A (BPA) at pH 6.5 with catalyst dosage of 0.34 g/L within 60 min under simulated sunlight irradiation, which 2.09 times higher than that of Bi7O9I3 prepared by the conventional hydrothermal route. Bi7O9I3-0.1 also exhibited higher photodegradation efficiency for a variety of organic pollutants such as tetracycline (TC, 93.1%), ciprofloxacin (CIP, 76.8%), phenol (73.2%), rhodamine B (RhB, 96.2%) and methylene blue (MB, 94.2%). The primary oxidative species inducing BPA degradation were •O2– and h+ determined by scavenger and EPR tests, and the carriers transfer mechanism in Bi7O9I3 was postulated. The photodegradation pathway of BPA was proposed on the basis of LC/MS analysis. The biological toxicity of degradation intermediates was reduced compared to that of BPA according to ECOSAR analysis. Reusability runs demonstrated the chemical and structural stability of the synthesized Bi7O9I3. This work provided a simple route to synthesize bismuth-rich photocatalysts for the degradation of environmental pollutants.

Amine-free synthesis of high-silica MFI zeolite by the conventional hydrothermal route

High-silica MFI zeolite can hardly be prepared by the conventional hydrothermal synthesis route in the absence of amines, which is ascribed to the competitive growth of quartz, magadiite, or kenyaite phase. In this work, these impurity phases were excluded from the synthetic gel through a low-temperature crystallization method, while the growth of zeolite phase was promoted by seed-directed and C2H5OH filling. Consequently, well-crystallized ZSM-5 samples with controllable Si/Al ratios (46–205) and uniform particle sizes were successfully prepared, and the crystallization process was tracked by multiple characterization techniques, pointing toward a nonclassical particle attachment crystallization process. Interestingly, we found that the optimal C2H5OH/SiO2 ratio can be proportionally reduced by decreasing the H2O/SiO2 ratio in the synthetic gel. More importantly, the obtained high-silica MFI zeolite exhibited a much higher catalytic stability than the conventional sample synthesized using tetrapropylammonium as the template during the methanol-to-propylene and n-butene cracking reactions, which may be attributed to its fewer defect sites determined by 1H magic angle spinning nuclear magnetic resonance techniques. Overall, this work provides an efficient route for the large-scale production of high-silica ZSM-5 samples.

Improved H2S sensitivity of nanosized BaSnO3 obtained by hydrogen peroxide assisted sol-gel processing

Barium stannate is a mixed-metal oxide with a perovskite structure and unique electric, catalytic, and sensing properties. Surface chemistry determines gas sensing behavior, which depends on materials synthesis and processing methods. A novel technique was invented for obtaining BaSnO3 nanoparticles using a hydrogen peroxide assisted sol-gel process. However, to date, the sensing behavior of such prepared barium stannate nanoparticles has not been investigated. In this work, we obtained pure and La-modified BaSnO3 by the hydrogen peroxide-assisted sol-gel method and comparatively studied the composition, microstructure, and gas sensing behavior using as a reference barium stannate prepared by a conventional hydrothermal route. The increased sensitivity and selectivity to H2S were observed for the sol-gel obtained BaSnO3, and the sensing behavior was improved at temperatures higher than 150 °C by La(5%)-modified of barium stannate. The sensing mechanism was revealed by in situ infrared and Raman spectroscopy. The superior sensitivity and selectivity of the sol-gel obtained materials were attributed to lower surface contamination by adsorbed carbonate groups compared to hydrothermally obtained BaSnO3. The surface modification by La3+ species further reduced the carbonate impurity and enhanced the adsorption and oxidation of H2S gas at the BaSnO3 surface.

From CsKTaF7 to CsNaTaF7 : Alkali Metal Cations Regulation to Generate SHG Activity.

Inorganic metal halides play important roles in wide range of areas including fluorescence, X-ray detection, and nonlinear-optics. Herein, two new mixed alkali metal tantalum fluorides, CsKTaF7 and CsNaTaF7 , have been obtained based on the strategy of cations regulation in A2 MF7 (A represents monovalent cations and M is d0 transition-metal cation) system by a conventional hydrothermal route. CsKTaF7 crystallizes in the centric Pnma space group, while CsNaTaF7 crystallizes in the polar Cmc21 space group and exhibits moderate and phase-matchable NLO activity. Both halides possess large optical band gaps above 5.0 eV. The crystal structure evolution, optical properties, and detailed theory calculations of these two halides were elucidated in this work.

Microfluidic Study of Bacterial Attachment on and Detachment from Zinc Oxide Nanopillars.

Nanopillars can influence how bacterial cells attach to a surface. Herein, we investigated whether self-assembled zinc oxide (ZnO) nanopillars synthesized on glass substrates via the conventional hydrothermal route possess anti-biofouling properties either by reducing the amount of initially attached cells or promoting the detachment of cells from the surface or both. To avoid complications associated with manual intervention methods of assessing bacterial attachment on nanopillar surfaces, we implemented a microfluidic approach. In our study, we synthesized two nanopillar topographies: a low surface density of ZnO nanopillars and a high surface density of ZnO nanopillars. Next, we mounted microfluidic channels to each of these substrates. This microfluidic approach allowed us to gently flow Pseudomonas aeruginosa, Staphylococcus aureus, or Bacillus subtilis cells onto the nanopillars for initial attachment before systematically increasing the flowrate to attempt to detach remaining attached cells without introducing air-liquid interface artefacts during the assay. Generally, initial bacterial attachment was similar across all substrates. However, cells consistently detached more readily from high-surface-density nanopillars compared to low-surface-density nanopillars. Electron microscopy revealed that cells that attached to high-surface-density nanopillars rested atop the nanopillars, fully exposed to microfluidic shear, whereas many cells became trapped in the void space between neighboring low-surface-density nanopillars, shielding these cells from detachment. Our findings indicate that self-assembled ZnO nanopillars can provide anti-biofouling properties under submerged flow but only if synthesized at high surface density.

Photocatalytic degradation of malachite green and methylene blue over reduced graphene oxide (rGO) based metal oxides (rGO-Fe3O4/TiO2) nanocomposite under UV-visible light irradiation

Reduced graphene oxide based iron oxide modified titania (rGO-Fe3O4/TiO2) was developed as a low-cost, stable, and reproducible photocatalyst, synthesized by conventional hydrothermal route. Structural and morphological features were investigated by X-Ray diffraction (XRD), Thermogravimetric analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). The incorporation of rGO-Fe3O4 to TiO2 shifted the light absorption of TiO2 from ultraviolet (UV) to visible region. The band gap energy of the synthesized photocatalyst rGO-Fe3O4/TiO2 reduced to 2.6 eV as compared to TiO2 (3.2 eV) which shifted the light absorption into visible region in order to utilize the solar energy effectually. The as-proposed rGO-Fe3O4/TiO2 and TiO2 photocatalysts were used for the photo-degradation of malachite green (MG) and methylene blue (MB) degradation. The as-prepared photocatalyst rGO-Fe3O4/TiO2 exhibited commendable photocatalytic efficiency (99%) comparative to pure TiO2 (67%) under visible light in 55 min for MG degradation. The active species were also identified using various scavengers by trapping holes and radicals generated during the photocatalytic degradation process. Subsequently, such photo-degradation output inferred that this ternary nanocomposite partakes a great potential for visible light driven MG and MB photocatalytic degradation.

Zinc and Sulfur Codoped Iron Oxide Nanocubes Anchored on Carbon Nanotubes for the Detection of Antitubercular Drug Isoniazid

Zinc and sulfur codoped iron oxide nanocubes on functionalized multiwalled carbon nanotubes (Zn@S-FeNC/f-CNTs) were synthesized by a conventional hydrothermal (HT) route followed by ultrasonication...

Cobalt-substituted iron-based wolframite synthesized via polyol route for efficient oxygen evolution reaction

Binary tungsten oxides with a wolframite crystal structure, such as FeWO4 and CoWO4, have poor electrocatalytic activity for the oxygen evolution reaction (OER). However, the incorporation of a third element into the crystalline framework increased the OER activity in an alkaline medium. Specifically, Co0.5Fe0.5WO4 prepared through a polyol route generated a current density of 10 mA cm−2 at a considerably small overpotential (η) and Tafel slope (331 mV and 36.8 mV dec−1, respectively). This overpotential value was superior to those of Co0.5Fe0.5WO4 fabricated through a conventional hydrothermal route (η at 10 mA cm−2 = 360 mV) and commercial RuO2 (365 mV), a benchmark catalyst for the OER. The turnover frequency (TOF) of the polyol-synthesized Co0.5Fe0.5WO4 was estimated to be 0.235 s−1 at an overpotential of 400 mV, while stable operation at 10 mA cm−2 was maintained for at least 24 h.

Photometric features and intense blue light emanation of Nd3+ doped SrTiO3 based nanophosphor for multi-functional applications

Abstract Herein, a series of SrTiO3:Nd3+ (1–11 mol %) nanophosphors has been prepared via a conventional hydrothermal route. Their anti-counterfeiting and latent fingerprint visualization applications are reported, which show important level-III features and unclonable tags. The cubic structure was confirmed by powdered X-ray diffraction studies with space group Pm-3m (No-221). The photoluminescence (PL) characterization results evinced that the nanophosphor emits intense blue light. The optimized nanophosphors were used to visualize latent fingerprints through recognizing level I-III ridges by a reduced background hindrance and can be utilized for visualizing latent fingerprints on difficult substrate surfaces with superior sensitivity, high contrast and selectivity. Further, a furthermost possible stochastic process to make unclonable anti-counterfeiting tags using optimized nanophosphor was designed to reduce counterfeit products. Therefore, it is believed that this optimized nanophosphor for visualization of latent fingerprints as well as unclonable anti-counterfeiting tags will find widespread use in forensic investigations and product safety applications.

Urea and surfactant assisted hydrothermal growth of ceria nanoparticles

Cerium oxide nanoparticles were prepared via a modified hydrothermal approach to reduce the reaction durations in the conventional hydrothermal route. Urea and NaOH were used together for the fast growth of ceria nanocubes within a short reaction period. The formation of Ce-O-Ce bonds to grow CeO2 nuclei with the help of urea, and the anisotropic growth in the base medium led to the formation of nanocube morphology. Cetyltrimethylammonium bromide (CTAB) was added further in the precursor solution as a capping and structure directing agent that directed the growth of ceria nanostructures from spherical to irregular polygonal morphology. Ceria nanocubes of 18−20 nm sizes with highly reactive (1 0 0) faces were formed after hydrothermal reaction. On the other hand, CTA+ group reduced the particle sizes to 8−10 nm with the (1 1 1) exposed stable faces. In addition, ceria nanostructures obtained with the assistance of surfactants show intrinsic oxygen vacancies and enhanced concentrations of Ce3+ in cubic fluorite structure. Furthermore, band gap and Urbach energy calculations show that the increase in structural disorder and contribution of the defects in ceria morphologies of the order: nanocubes < nanoplates < polygonal nanostructures < nanospheres. The present research indicated a novel approach to synthesize ceria nanoparticles within short reaction durations.

Crystallization of as-Mesocellular Silica Foam into Hierarchical TS-1 Zeolites by Conventional Hydrothermal and Dense-Gel Routes for Oxidation Reactions.

Crystallization of as-mesocellular silica foam (as-MCF) into TS-1 zeolites by conventional hydrothermal and dense-gel routes is reported. The TS-1 synthesized through the dense-gel route (TS-1-d) showed higher meso-macroporosity (0.311 vs 0.233 cm3/g), smaller particle size (130 vs 305 nm), and enhanced external surface area (86 vs 31 m2/g) than that synthesized under conventional hydrothermal conditions (TS-1-h). These might suggest that an organic template from as-MCF acted as mesoporogen in the dense-gel synthesis; however, segregation of the organic template and the synthesis mixture occurred in the conventional hydrothermal synthesis. The obtained TS-1 from the crystallization of as-MCF showed an enhanced framework Ti. The turnover frequencies (h–1) of TS-1-d toward hydroxylation of phenol and oxidation of dibenzothiophene (DBT) were 2 and 5 times, respectively, higher than those by TS-1-h. The DBT conversion by TS-1-d reached >99.0%, while it was only 63% by TS-1-h, suggesting the potential of TS-1-d for deep desulfurization of the fuels. Consequently, the crystallization of as-mesoporous materials through the dense-gel route is a promising approach to prepare TS-1 zeolites with smaller particle sizes and enhanced mesoporosity.

A Facile Microwave-Assisted Hydrothermal Synthesis of Graphene Quantum Dots for Organic Solar Cell Efficiency Improvement

Carbon-based nanomaterials have successively remained at the forefront of different research fields and applications for years. Understanding of low-dimension carbon material family (CNT, fullerenes, graphene, and graphene quantum dots) has arrived at a certain extension. In this report, graphene quantum dots were synthesized from graphene oxide with a microwave-assisted hydrothermal method. Compared with conventional time-consuming hydrothermal routes, this novel method requires a much shorter time, around ten minutes. Successful formation of quantum dots derived from graphene sheets was verified with microscopic and spectroscopic characterization. Nanoparticles present a diameter of about 2-8 nm, blue emission under ultraviolet excitation, and good dispersion in polar solvents and can be collected in powder form. The synthesized graphene quantum dots were utilized as a hole transport layer in organic solar cells to enhance the cell quantum efficiency. Such quantum dots possess energy levels (Ec and Ev) relevant to HOMO and LUMO levels of conductive polymers. Mixing P3HT:PCBM polymer and graphene quantum dots of sufficient extent notably helps reduce potential difference at interfaces of the two materials. Overall efficiency consequently advances to 1.43%, an increase of more than 44% compared with pristine cells (0.99%).

Surface plasmons enhanced band-edge emission in Ni nanoparticles decorated ZnO nanorods arrays architecture

We report nickel (Ni) nanoparticles (NPs) surface plasmons assisted enhanced photoluminescence behaviour in Ni-decorated ZnO NRs arrays architecture. ZnO NRs arrays architecture was grown on the Si substrate by a conventional hydrothermal route, followed by Ni NPs were decorated on the surface of ZnO NRs arrays architecture by pulsed laser deposition technique. The XRD and Raman analyses confirm the grown nanostructure is in hexagonal wurtzite structure. On Ni NPs decoration, a more than 14-fold enhancement in the band-edge emission with simultaneous suppression in the visible emission is observed. The improved PL emission can be attributed to the resonant coupling between the exciton emission of ZnO NRs arrays and the surface plasmons of Ni NPs. The energy band diagram demonstrates the interfacial charge transfer that takes place from the trapping states of ZnO NRs arrays architecture to Ni NPs, then surface plasmons bands of Ni NPs to the conduction band of ZnO NRs arrays architecture. Our experimental results reveal the decoration of Ni NPs on ZnO NRs arrays architecture is an effective means to tailor the optical properties of ZnO nanostructures.

Preparation and characterization of antimony sulphide nanostructure

Designing and Controlling of the size and morphology of the nanostructured materials is important for photovoltaic and photocatalytic applications. Herein, we report a new efficient approach to prepare different nanostructures of antimony sulphide. The conventional hydrothermal routes can be modified to control the size and morphology of the materials we have been prepared pedicellate flower-like nanostructure of antimony sulphide by quenched hydrothermal method (modified hydrothermal method). The prepared nanostructured materials were analysed using XRD, SEM. The powder X-ray diffraction pattern shows the Sb2S3 crystals belong to the orthorhombic phase with calculated lattice parameters a = 1.190 nm, b = 1.132 nm, and c = 0.390 nm. The morphological changes have been recorded using scanning electron microscope.

In situsynchrotron pair distribution function analysis to monitor synthetic pathways under electromagnetic excitation

In situpair distribution function analysis reveals that electromagnetic radiation exposure during SnO2nanoparticle growth alters local atomic structure and the synthetic pathway compared to conventional hydrothermal synthesis routes.

Efficient synthesis of high silica SSZ-13 zeolite via a steam-assisted crystallization process

High silica SSZ-13 zeolite was synthesized by an efficient and green steam-assisted crystallization (SAC) method under a low alkalinity and low organic templates amount system. The as-prepared samples were characterized by XRD, SEM, N2 adsorption–desorption, TG–DTG and NH3-TPD. The results showed that the SAC method can not only remarkably improve zeolite yield but also enhance the crystallization rate of SSZ-13 zeolite compare to conventional hydrothermal route. Meanwhile, it was also found that the various content of the organic structure directing agent (N,N,N-trimethyladamantammonium hydroxide, TMAdaOH) in the dry gel can adjust flexibly the crystal size, morphology and acidity of samples. The zeolite samples with smaller particles and more strong acidity amount were more likely obtained under the higher TMAdaOH/SiO2 ratio (0.2) condition. In addition, the catalytic evaluation in methanol-to-olefins (MTO) reaction showed that the high silica SSZ-13 catalysts synthesized by SAC method exhibited longer lifetime and comparative selectivity to ethylene and propene than those of the SSZ-13s obtained by conventional hydrothermal route. Thus, the SAC route is believed to be a competitive strategy to synthesize high silica SSZ-13 zeolites with improved MTO catalytic performance.

One-pot grinding method to BiO(HCOO)xI1−x solid solution with enhanced visible-light photocatalytic activity

Considering that conventional hydrothermal route to prepare photocatalysts is energy-consumable and difficult to scale-up, herein, uniform bismuth oxide formate (BiOHCOO; BiOR) nanosheets were firstly prepared from solid-state chemical reaction by a facile room-temperature grinding method. Furthermore, since BiOR could only respond to UV light, thin-nanosheet-based flowerlike BiO(HCOO)xI1−x solid solutions were synthesized via a one-pot method by adding KI into the BiOR reaction mixture and continuously grinding for an additional duration. As compared with BiOR, the resulting solid solution with x = 0.57 possessed narrower band gap, optimal energy levels and higher surface areas, leading to much higher visible-light photocatalytic activity for multiple pollutants degradation including rhodamine B (RhB), malachite green (MG) and colorless bisphenol A (BPA). This work demonstrates an easily-handling and eco-friendly solid-state reaction route to solid solutions with excellent visible-light photocatalytic activity. Good photocatalytic performance was also confirmed by electrochemical techniques.

Preparation of delafossite–type CuFeO2 powders by conventional and microwave–assisted hydrothermal routes for use as photo–Fenton catalysts

In this work, delafossite–type CuFeO2 powders were prepared by conventional hydrothermal and microwave–assisted hydrothermal routes and employed as potential catalysts in photo–Fenton reaction. The degradation efficiency of Reactive Red 141 dye under visible light was investigated. The solids were characterized by XRD, FTIR, N2 adsorption–desorption isotherms, SEM/EDX and diffuse reflectance spectroscopy. The sample prepared by microwave irradiation presented higher values of specific surface area and total pore volume as well as smaller band–gap energy. The synergistic effects of these properties favored the superior catalytic activity when compared to the material prepared by the conventional hydrothermal route. About 98% of dye degradation was obtained at 30 min for the CuFeO2 sample prepared by microwave irradiation against 84% at 150 min for that prepared by conventional method. In addition, the CuFeO2 catalyst prepared by microwave route showed high chemical stability and dye degradation efficiency after four cycles.

Synthesis of zeolite P1 from fly ash under solvent-free conditions for ammonium removal from water

In this work, zeolite P1 is synthesized from fluidized bed fly ash (FA) via a solvent-free process. The formation of zeolite P1 is investigated as a function of crystallization reaction time. The solid mixture of FA and Na2SiO3·9H2O with a mole ratio of Na:Al:Si = 1.5:1:1.7 can be converted to zeolite P1 at 80 °C for 24–96 h. XRF, XRD, SEM/EDS, FTIR, TG/DSC and BET techniques are used to test the properties of resultant zeolite products. The efficiencies of the resultant zeolite for ammonium adsorption are evaluated on factors including solution pH, NH4+ ions concentration, temperature and adsorption time. The kinetic data and adsorption equilibrium data fit satisfactory with the Ho's pseudo-second-order kinetic model and Langmuir model. The maximum ammonium adsorption capacity of zeolite P1 (22.9 mg/g) can be reached within 40 min at optimal pH of 6. The adsorption performance is higher than many of the natural zeolites and closely similar to the zeolites synthesized from fly ash through the conventional hydrothermal route. Our study not only provides new insights into the preparation of zeolite from fly ash, but also reveal that the zeolite P1 synthesized through solvent-free route is a promising material for ammonium removal.