Wet Chemical Synthesis Route Research Articles

Deciphering the influence of support in the performance of NiFe2O4 catalyst for the production of hydrogen fuel and nanocarbon by methane decomposition

Wet chemical synthesis route was used to synthesis nickel ferrite (NiFe2O4) nanoparticle. Later on the synthesized NiFe2O4 were supported on the surface of three traditional supports such as Al2O3, MgO and TiO2 to get NiFe2O4/Al2O3, NiFe2O4/TiO2 and NiFe2O4/MgO catalysts. The activity profile of each catalyst was evaluated in a fixed-bed reactor for direct methane decomposition at 800 °C. For both fresh and spent catalysts, many characterization techniques have been employed mainly XRD, FESEM, HRTEM, Raman spectroscopy, TGA, and nitrogen adsorption-desorption isotherm. X-ray powder diffraction studies revealed that all synthesized catalysts have a cubic spinel crystal structure. The XRD confirm the presence of NiFe2O4 particles in the component of fresh NiFe2O4/MgO, NiFe2O4/TiO2 and NiFe2O4/Al2O3 catalysts. Temperature Program Reduction (TPR) unveiled the presence of Ni oxides and Fe oxides by displaying reduction peaks in their respective temperature regions. The N2 adsorption-desorption isotherms of the fresh all catalysts reveal that these catalysts have a mesoporous structure. Activity data concluded NiFe2O4/MgO to be the most active catalysts among the tested catalysts methane conversion magnitude of 41.13 % and H2 formation rate of 84.40 × 10−5 mol H2 g−1 min−1. On the other hand, the H2 formation rate drastically declined and very poor activity of both NiFe2O4/TiO2 and NiFe2O4/Al2O3 catalysts was observed in the current work. XRD patterns, FESEM images and TGA analysis of spent NiFe2O4/MgO catalyst shown the filamentous carbon formation which secondarily confirm its higher activity, while its absence in catalysts of NiFe2O4/TiO2 and NiFe2O4/Al2O3. TGA analysis of the carbon deposited on the NiFe2O4/MgO catalyst showed that the amount of carbon was approximately 64 wt%. It was suggested that the formation of nickel-iron carbide revealed by XRD studies of spent catalysts may be the factor related to their poor activity while discussing the structure-activity relationship. Likewise, the higher degree of dispersion related to NiFe2O4/MgO as displayed by XRD, FESEM and TPR investigations, played a vital role in accelerating the rate of hydrogen formation.

Detection of water pollutants using super-hydrophobic porous silicon-based SERS substrates.

Super hydrophobic porous silicon surface is prepared using a wet chemical synthesis route. Scanning electron microscopic investigation confirms a correlation between pore size and reaction time. SERS substrates are prepared by silver nanoparticle deposition on porous silicon surface. They exhibit excellent characteristics in terms of sensitivity, reproducibility, stability, and uniformity. They could detect rhodamine 6G in femtomolar range with SERS enhancement factor of ~ 6.1 × 1012, which is best ever reported for these substrates. Molecule-specific sensing of water pollutants such as methylene blue, glyphosate, andchlorpyrifos, is demonstrated for concentrations well below their permissible limits along with excellent enhancement factors. Porous silicon substrate functionalized with Ag nanoparticles demonstrates to be a promising candidate for low-cost, long-life, reliable sensors for environmental conservation applications.

One pot synthesis of nanostructured bismuth fluoride tailored for symmetric supercapacitor performance

Organic molecule stabilized face-centered cubic structured bismuth fluoride (BiF3) nanoparticles (NPs), space group: Fm-3 m, were prepared using a wet chemical synthesis route for symmetric supercapacitor application. For freestanding three electrode system, at current density (Cd) 3.3 A.g−1, the material displayed a maximum specific capacitance (SCp) value 717.3 F.g−1. The symmetric device based on BiF3 attained a maximum specific capacity (SC) value of 228.4 mAh.g−1 at 0.06 A.g−1. At the current density of 0.30 A.g−1, the device displayed the energy density (Ed) and power density (Pd) values of 0.17 Wh.kg−1 and 343.7 W.kg−1, respectively. Furthermore, the fabricated symmetric supercapacitor displayed 90% of capacity retention and 95% of coulombic efficiency at 0.12 A.g−1 for 1000 galvanostatic charge–discharge (GCD) cycles. The symmetric supercapacitor based on BiF3 NPs exhibited excellent electrochemical performance, which could be an appropriate choice for application in different integrated energy storage systems.

Optimizing performance: Achieving high capacitance and cycling durability in alkaline electrolyte with SnO2/SnSe||AC/KOH-based aqueous hybrid supercapacitor

A facile wet-chemical assisted synthesis route is adapted to prepare a novel SnO2/SnSe nanocomposite for the time to construct an aqueous asymmetric hybrid supercapacitor (AAHSC). The detailed characterization reveals the appropriate formation of micro flower-like SnO2-SnSe nanocomposite-covered with SnSe network to provide a conductive support and facilitate charge transport during the electrochemical processs. Compared with pure SnO2 micro flowers and SnSe electrodes, the SnO2-SnSe nanocomposite electrode delivers a brilliant charge storage performance. A rapid charge transport pathways was accomplished due to the lowest charge transfer resistance, resulting in a high capacitance and improved charge storage properties in an aqueous alkaline electrolyte solution with incredible reversibility and rate capability. Inspired by the excellent charge storage and capacitive properties, a two-cell mode-based AAHSC was built with SnO2-SnSe nanocomposite (cathode) and activated carbon (AC) as an anode (symbolized as SnO2-SnSe||AC/KOH) displayed the highest energy of 33.4 Wh/kg at a maximum power of 4003.7 W/kg, operating in a voltage of 1.6 V with excellent cycling stability of 89.5 %.

Ab initio investigations on the structural and optical properties of sol-gel synthesized bismuth telluride nanoparticles

Bismuth telluride nanopowders are prepared by a simple but efficient wet chemical synthesis route namely Sol-gel auto-combustion. X-ray diffraction (XRD) and Scanning Electron Microscopic (SEM) analyses were used to study the structural and morphological characteristics. The crystallinity of the produced samples were verified using XRD, and composition was confirmed by Energy Dispersive x-ray analysis (EDAX) measurements. The optical characterization of the prepared bismuth nanopowders were also carried out using Diffused Reflectance Spectroscopy (DRS) and Raman spectroscopic analysis. The optical bandgap of the prepared nanopowder is found to be 3.27 eV. Raman active modes of the sample are also reported. The optical properties of the Bismuth telluride nanopowder are rarely reported. The optical constant evaluation of the prepared sample point towards the probable application of these materials in optoelectronic devices in addition to its conventional thermoelectric applications.

Dielectric capacitance and energy storage performances of organic molecule stabilized hexagonal lead iodide with a layered network

Nanostructured lead iodide particles were synthesized by applying a wet chemical synthesis route in presence of aminobenzene and fluoro-aminobenzene as ligands. The ligands were performed as the stabilizer of the particles. Two types of devices were designed using aminobenzene and fluoro-aminobenzene stabilized lead iodide. The dielectric capacitance, AC-conductivity, field-driven polarization and energy storage performances of the devices were investigated under varying temperature and frequency conditions. The electrical performance of fluoro-aminobenzene stabilized lead iodide-based device exhibited superior performance than that of aminobenzene-stabilized lead iodide-based devices. The fluoro-aminobenzene based device showed the maximum dielectric constant value 398 under the frequency of 100 Hz at 80 °C and maintained a low dielectric loss and high quality factor within the frequency range from 100 Hz to 2 kHz. Both the devices demonstrated the small polaron hopping conduction mechanism. The fluoro-aminobenzene based device maintained a fatigue-free unipolar hysteresis loop under 4 kV/mm with the maximum polarization value of 0.21 μC/cm2 and attended a stable charge and discharge energy density for the period of 103 cycles.

Photoluminescence properties of Eu3+-doped Na2CaSiO4 phosphor prepared by wet-chemical synthesis route

The present investigation focuses on the development of Eu3+ activated phosphors for near ultraviolet (NUV) excited light emitting diode (LED) applications. In this investigation, we have synthesized a series of Na2CaSiO4:Eu3+phosphors via wet-chemical method and characteristic of synthesized phosphors have been analyzed by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Thermo gravimetric analysis– Differential thermal analysis (TGA–DTA) and photoluminescence (PL) techniques. The recorded excitation band indicates a broad excitation band centered at 262 nm due to charge transfer (CT) band and sharp peaks at 395 nm and 466 nm due to 7F0→5L6 and 7F0→5D2 transition of Eu3+ ions. The highest excitation intensity was observed at 396 nm wavelength. Therefore under 396 nm excitation, the emission spectrum showed characteristics peaks located at 595 nm and 615 nm, which are attributed due to the 5D0→7F1 and 5D0→7F2 transition of Eu3+ ions. Emission spectra shows dominant emission peak at orange region around 595 nm due to the magnetic dipole transition of5D0→7F1. In addition, the effects of the Eu3+ ions on the emission intensity were investigated, it was found that the emission intensity increases as the concentration of Eu3+ ions increases up to 0.5 mol%. Thereafter, PL emission intensity was decreased due to concentration quenching. The CIE Chromaticity coordinate of the prepared phosphor was located in the orange region around (0.584, 0.421) with high color purity. As per the investigation of prepared Na2CaSiO4:Eu3+phosphors, it was concluded that it is a promising candidate for lighting and display applications.

Ruthenium and Nickel Molybdate-Decorated 2D Porous Graphitic Carbon Nitrides for Highly Sensitive Cardiac Troponin Biosensor.

Two-dimensional (2D) layered materials functionalized with monometallic or bimetallic dopants are excellent materials to fabricate clinically useful biosensors. Herein, we report the synthesis of ruthenium nanoparticles (RuNPs) and nickel molybdate nanorods (NiMoO4 NRs) functionalized porous graphitic carbon nitrides (PCN) for the fabrication of sensitive and selective biosensors for cardiac troponin I (cTn-I). A wet chemical synthesis route was designed to synthesize PCN-RuNPs and PCN-NiMoO4 NRs. Morphological, elemental, spectroscopic, and electrochemical investigations confirmed the successful formation of these materials. PCN-RuNPs and PCN-NiMoO4 NRs interfaces showed significantly enhanced electrochemically active surface areas, abundant sites for immobilizing bioreceptors, porosity, and excellent aptamer capturing capacity. Both PCN-RuNPs and PCN-NiMoO4 NRs materials were used to develop cTn-I sensitive biosensors, which showed a working range of 0.1–10,000 ng/mL and LODs of 70.0 pg/mL and 50.0 pg/mL, respectively. In addition, the biosensors were highly selective and practically applicable. The functionalized 2D PCN materials are thus potential candidates to develop biosensors for detecting acute myocardial infractions.

Insights into the gas sensor materials: Synthesis, performances and devices

Recently, the intelligent, smart gas sensing devices have shown great prospects in applications of gas component recognition and concentration detection, which largely depends on the precise structures and compositions of sensing layers. Various synthetic strategies are promising for the scalable production and performance optimization of the sensing materials. In this review, different gas sensing materials with controlled preparation such as wet-chemical synthesis, electrospinning method, vapor-phase synthesis and exfoliation routes are summarized. Then, the representative design strategies and gas sensing performances in gas sensors are also discussed. Finally, the recent progress of some gas sensing devices is presented, with the emphasis on their device structure, circuit design, and applications. It is believed that this review will provide some guidelines for designing novel gas sensing materials with controllable synthetic methods and sensing behaviors for advanced gas sensors.

Identifying the formation of antimony-based sesquioxide phase materials via wet and solid-state chemical synthesis routes — a detailed study

Identifying the formation of antimony-based sesquioxide phase materials via wet and solid-state chemical synthesis routes — a detailed study

Hierarchical CuO nanostructured materials for acetaldehyde sensor application

A nanocrystalline CuO with mixed morphologies (nanorods, nanoplates and nanoparticles) were prepared using simple room temperature wet chemical synthesis route. The nanostructured CuO material was characterized using FESEM, TEM, EDS, elemental mapping, UV–visible spectroscopy, and BET surface area techniques for various physicochemical characteristics. The gas sensor device was fabricated using CuO nano-powder and its acetaldehyde gas sensing properties was investigated. The CuO sensor showed excellent sensing response towards 20–100 ppm acetaldehyde. The acetaldehyde response of the CuO sensor was recorded at various operating temperatures as well as concentrations. The responses of 418% and 115% were noted for 100 ppm and 20 ppm acetaldehyde concentration at 180 °C respectively. The higher selectivity of the CuO sensor was observed towards acetaldehyde among various gases. The transient response of the sensor was observed to be consistent with concentrations. The dynamic repetitive response of the sensor was tested at 100 ppm acetaldehyde that revealed to be same. The sensor's stability was tested and observed to be quite stable. A brief acetaldehyde sensing mechanism for CuO sensor was elucidated. The easy and large-scale formation of CuO nanostructures without growth controlling surfactants, and the good selectivity of the high response acetaldehyde sensor at relatively low operating temperatures may pave pathway for future gas sensor technology.

New Insights on the Nickel State Deposited by Hydrazine Wet-Chemical Synthesis Route in the Ni/BCY15 Proton-Conducting SOFC Anode.

Yttrium-doped barium cerate (BCY15) was used as an anode ceramic matrix for synthesis of the Ni-based cermet anode with application in proton-conducting solid oxide fuel cells (pSOFC). The hydrazine wet-chemical synthesis was developed as an alternative low-cost energy-efficient route that promotes ‘in situ’ introduction of metallic Ni particles in the BCY15 matrix. The focus of this study is a detailed comparative characterization of the nickel state in the Ni/BCY15 cermets obtained in two types of medium, aqueous and anhydrous ethylene glycol environment, performed by a combination of XRD, N2 physisorption, SEM, EPR, XPS, and electrochemical impedance spectroscopy. Obtained results on the effect of the working medium show that ethylene glycol ensures active Ni cermet preparation with well-dispersed nanoscale metal Ni particles and provides a strong interaction between hydrazine-originating metallic Ni and cerium from the BCY15 matrix. The metallic Ni phase in the pSOFC anode is more stable during reoxidation compared to the Ni cermet prepared by the commercial mechanical mixing procedure. These factors contribute toward improvement of the anode’s electrochemical performance in pSOFC, enhanced stability, and a lower degradation rate during operation.

Structural, magnetic and magnetoelectric investigations on CoFe2O4 prepared via various wet chemical synthesis route : A Comparative Study

Magnetostrictive materials are potential candidates for many applications such as sensors, actuators, transducers, and other magnetoelectric applications. Cobalt Ferrite (CoFe2O4) has proven to be favourable in comparison to commonly used magnetostrictive materials due to its high magnetostriction coefficient and it’s preparation being cost effective. This work deals with the preparation of CoFe2O4 (CFO) using four different wet chemical synthesis techniques in the form of autocombustion, co-precipitation, sol–gel and hydrothermal methods. Same conditions of heat treatment have been maintained for all the methods which facilitates a fair comparison of the performance of the samples prepared by various methods. The prepared CFO samples were subjected to subsequent characterization of their structural, magnetic, magnetostrictive and magnetoelectric properties. Static and dynamic magnetoelectric measurements were carried out on trilayered composites comprising of CFO synthesized by hydrothermal and sol–gel methods. Effect of in-plane and transverse compressive stress on the magnetoelectric response of CFO/PZT/CFO trilayered structure have been studied. All the experimental characterisations indicated the sample synthesized by hydrothermal method to yield better properties. The results thus reveal the importance of synthesis route towards attaining an improved magnetic, magnetostrictive and magnetoelectric properties of CFO.

Metal Oxide-Based Photocatalytic Paper: A Green Alternative for Environmental Remediation

The interest in advanced photocatalytic technologies with metal oxide-based nanomaterials has been growing exponentially over the years due to their green and sustainable characteristics. Photocatalysis has been employed in several applications ranging from the degradation of pollutants to water splitting, CO2 and N2 reductions, and microorganism inactivation. However, to maintain its eco-friendly aspect, new solutions must be identified to ensure sustainability. One alternative is creating an enhanced photocatalytic paper by introducing cellulose-based materials to the process. Paper can participate as a substrate for the metal oxides, but it can also form composites or membranes, and it adds a valuable contribution as it is environmentally friendly, low-cost, flexible, recyclable, lightweight, and earth abundant. In term of photocatalysts, the use of metal oxides is widely spread, mostly since these materials display enhanced photocatalytic activities, allied to their chemical stability, non-toxicity, and earth abundance, despite being inexpensive and compatible with low-cost wet-chemical synthesis routes. This manuscript extensively reviews the recent developments of using photocatalytic papers with nanostructured metal oxides for environmental remediation. It focuses on titanium dioxide (TiO2) and zinc oxide (ZnO) in the form of nanostructures or thin films. It discusses the main characteristics of metal oxides and correlates them to their photocatalytic activity. The role of cellulose-based materials on the systems’ photocatalytic performance is extensively discussed, and the future perspective for photocatalytic papers is highlighted.

Structures and Role of the Intermediate Phases on the Crystallization of BaTiO3 from an Aqueous Synthesis Route.

Carbonate formation is a prevailing challenge in synthesis of BaTiO3, especially through wet chemical synthesis routes. In this work, we report the phase evolution during thermal annealing of an aqueous BaTiO3 precursor solution, with a particular focus on the structures and role of intermediate phases forming prior to BaTiO3 nucleation. In situ infrared spectroscopy, in situ X-ray total scattering, and transmission electron microscopy were used to reveal the decomposition, pyrolysis, and crystallization reactions occurring during thermal processing. Our results show that the intermediate phases consist of nanosized calcite-like BaCO3 and BaTi4O9 phases and that the intimate mixing of these along with their metastability ensures complete decomposition to form BaTiO3 above 600 °C. We demonstrate that the stability of the intermediate phases is dependent on the processing atmosphere, where especially enhanced CO2 levels is detrimental for the formation of phase pure BaTiO3.

Binder-free pseudocapacitive nickel cobalt sulfide/MWCNTs hybrid electrode directly grown on nickel foam for high rate supercapacitors

In this study, in-situ decoration of a binder-free pseudocapacitive NiCo2S4 and NiCo2S4/MWCNTs hybrid electrode has been synthesized via a wet chemical synthesis route on Ni foam. The hybrid electrodes of bimetallic metal sulfides were investigated using the X-ray diffraction technique and scanning electron microscopy. The electrochemical technique was used to investigate the electrochemical properties of the synthesized bimetallic metal sulfide materials. The good galvanostatic discharge time of 1077 s, the areal capacitance of 5.38 F/cm2, and specific capacitance of 2210 F/g were observed for NiCo2S4/MWCNTs hybrid electrode materials, respectively at 3 mA/cm2. The results show that the addition of highly conductive, MWCNTs, and the synergic effects of bimetallic sulfides (Ni, Co) greatly contribute to the excellent electrochemical properties, making the NiCo2S4/MWCNTs hybrid electrode as a potential material for supercapacitor applications.

Pore penetration of porous catalyst supports by in-situ-adsorbed, agglomeration-quenched nanoparticles from pulsed laser ablation in supercritical CO2

To synthesize nanoparticles for catalytic applications, pulsed laser ablation (PLA) in liquids has been established as a cost-effective method complementary to wet-chemical synthesis routes. Due to mass transport limitations in water, recent studies conducted PLA in supercritical CO2 (scCO2) to use the superior transport properties. Unfortunately, PLA in scCO2 so far led to the formation of bigger particles and agglomerates, which are unfavorable for the application as catalytically active material. As will be shown in this paper, the former are being avoided by means of an in-situ deposition approach of gold and platinum in scCO2 in presence of mesoporous γ-Al2O3 support. Transmission electron microscopy reveals that the resulting nanoparticle size is quenched while careful adjustment of the mixing conditions during PLA is shown to significantly reduce the agglomeration tendency. Cross-sections of the heterogeneous catalyst prove, that the nanoparticles penetrate the mesoporous support up to 109 nm deep.

Preparation of single-layer graphene based on a wet chemical synthesis route and the effect on electrochemical properties by double layering surface functional groups to modify graphene oxide

In this paper, we reported the effect of secondary intercalation by introducing a hydroxyl group (–oxide by hydroxyl (OH)) on the surface of graphene (GO) to prepare a large quantities of low-layer graphene. The (Scanning Electron Microscope) SEM,(Transmission Electron Microscope) TEM and (Atomic Force Microscope) AFM analyses showed that the graphene distribution was uniform with an atomic thickness of approximately 1–2 layers. The standardless standard quantitative analysis indicated that the O content was only 3.53% and the impurity element content was only 0.29%, which indicated that the graphene was reduced. (X-ray photoelectron spectroscopy) XPS and FT-IR analyses demonstrated that most oxygen-containing functional groups between the graphene sheets were converted and removed. When tested as a supercapacitor electrode, RGO-C2 exhibited significant electrochemical enhancement and better cycle stability than an electrode produced by a conventional modified Hummers’ method. The specific capacity, energy density and power density of RGO-C2 are respectively 278.91 F g−1, 38.74 W h kg−1, and 50 W kg−1. This experimental study can provide research guidance for the design of modification of oxygen-containing functional groups on the surface of GO.

Cerium Oxide Nanoparticles and Their Efficient Antibacterial Application In Vitro against Gram-Positive and Gram-Negative Pathogens.

In this study, the antibacterial activity of cerium oxide nanoparticles on two Gram-negative and three Gram-positive foodborne pathogens was investigated. CeO2 nanoparticles (CeO2 nps) were synthesized by a Wet Chemical Synthesis route, using the precipitation method and the Simultaneous Addition of reactants (WCS–SimAdd). The as-obtained precursor powders were investigated by thermal analysis (TG–DTA), to study their decomposition process and to understand the CeO2 nps formation. The composition, structure, and morphology of the thermally treated sample were investigated by FTIR, Raman spectroscopy, X-ray diffraction, TEM, and DLS. The cubic structure and average particle size ranging between 5 and 15 nm were evidenced. Optical absorption measurements (UV–Vis) reveal that the band gap of CeO2 is 2.61 eV, which is smaller than the band gap of bulk ceria. The antioxidant effect of CeO2 nps was determined, and the antibacterial test was carried out both in liquid and on solid growth media against five pathogenic microorganisms, namely Escherichia coli, Salmonella typhimurium, Listeria monocytogenes, Staphylococcus aureus, and Bacillus cereus. Cerium oxide nanoparticles showed growth inhibition toward all five pathogens tested with notable results. This paper highlights the perspectives for the synthesis of CeO2 nps with controlled structural and morphological characteristics and enhanced antibacterial properties, using a versatile and low-cost chemical solution method.

Pt mechanical dispersion on non-porous alumina for soot oxidation

A sustainable mechanical method to disperse Pt particles on the surface of non-porous α-Al2O3 microparticles is reported. The hierarchical Pt/α-Al2O3 catalyst possesses a metal specific surface area one order of magnitude lower than the state-of-the-art γ-Al2O3 – supported Pt catalysts of similar metal composition and high alumina specific surface area. The relatively large size of the Pt particles seems to favor the catalytic soot oxidation in spite of their relatively low dispersion. As a result, the temperature of half conversion (T50 = 440 °C) is lower when compared with conventional Pt/γ-Al2O3 prepared by the wet impregnation chemical synthesis route.