Wet Chemical Technique Research Articles

New Synthesis Strategies for Transition-Metal Phosphide Based Water Splitting Electrocatalysts

Transition metal phosphides (TMPs) have emerged as an intriguing class of efficient electrocatalyst finding widespread application in hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Currently adopted wet chemistry and solid-gas synthesis techniques rely on the use of surfactants/ toxic organic solvents or toxic gas which restricts facile fabrication of TMPs. Moreover, hybridizing TMPs with suitable carbon support (graphene, carbon nanotubes etc.) favorably optimizes the electrochemical activity of TMPs. However, this is often achieved via post-synthesis modification further complicating the synthesis procedure.In an attempt to overcome these limitations, we have recently developed a solid state, phosphine free method to fabricate Co2P nanoparticles encapsulated N, P co-doped CNTs. These as prepared catalysts were applied as a bi-functional electrocatalyst for HER and OER. In order to increase the surface area and loading of Co2P nanoparticles, we next designed Co2P encapsulated CNTs grafted N, P co-doped hollow spheres via MOF-templated strategy with superior catalytic activity compared to Co2P@CNTs.[1] [2]We then introduced sub-2nm IrP2 nanoparticles encapsulated bilayer N, P co-doped graphene as a novel electrocatalyst which exhibits better HER activity than benchmark Pt/C in acid, neutral as well as the alkaline medium. Interestingly, careful tuning of the reaction parameters also enables the synthesis of phase pure Ir2P.In conclusion, the versatile strategy developed here can be extended to fabricate a variety of TMPs with widely varied applications.[1] D. Das and K.K. Nanda, Nano Energy, 2017, 30, 303-311[2] D. Das, A.Das, M.Reghunath and K.K Nanda, Green Chemistry, 2017,19, 1327-1335

A novel surface modification of silicon nanowires by polydopamine to prepare SiNWs/NC@NiO electrode for high-performance supercapacitor

In this article, we synthesized a ternary silicon nanowire arrays (SiNWs)-based composite electrode by a novel wet-chemical technique for the application in high-performance supercapacitors. Initially, the polydopamine (PDOP) was loaded as the modifier to enhance the surface hydrophilicity properties of the SiNWs. Meanwhile, PDOP serves as the nitrogen-doped carbon source. Subsequently, the conformal PDOP layer was used as the template to guide the preferential deposition of the nickel oxide (NiO) precursor. Finally, the SiNWs/NC@NiO composite electrode was obtained by a one-step calcination process. The existence of the N-doped carbon was characterized by the XPS and element analysis characterizations. The FE-SEM characterizations revealed the formation processes of NiO nanoflakes precursor on PDOP layer. The N-doped carbon and nickel oxide play a synergistic role in enhancing the electrochemical performance in aqueous electrolytes. The as-prepared SiNWs/NC@NiO composite electrode shows an areal specific capacitance as high as 110 mF/cm2 at the current density of 1.0 mA/cm2.

Ag2O/GO/TiO2 composite nanoparticles: synthesis, characterization, and optical studies

Ag2O/GO/TiO2 composite nanoparticles were synthesized via a two-stage route including wet chemical and sol-gel techniques. The phase regarding the composition and morphology of composite nanoparticles was characterized using X-ray diffraction (XRD), Fourier transfer infrared (FT-IR) spectroscopy, and field emission scanning electron microscopy (FESEM). The structural studies revealed the successful formation of 300-nm Ag2O/GO/TiO2 composite spheres self-assembled to 35-nm particle aggregates. UV-Vis diffuse reflectance spectroscopy (DRS) was utilized to investigate optical properties. The results indicated an absorption edge in the UV region with a band-gap equivalent to 3.2 eV for Ag2O/GO/TiO2 composite nanoparticles. The morphological features of the sample were investigated with a Zeiss (EM10C, Germany) transmission electron microscope (TEM) operating at 100 kV.

Facile High Throughput Wet-Chemical Synthesis Approach Using a Microfluidic-Based Composition and Temperature Controlling Platform.

The wet-chemical technique has been widely applied in material synthesis. In recent years, high throughput (HT) technique has shown its potential in parallel synthesis and the investigation of synthesis parameters. However, traditional ways of HT parallel synthesis require costly equipment and complex operating procedures, restricting their further applications. In this paper, we prepared a cost-effective and timesaving microfluidic-based composition and temperature controlling platform to carry out HT wet-chemical synthesis in a facile and automated workflow. The platform uses a microfluidic chip to generate 20–level concentration gradients of the two reagents and uses 100–channel reactor arrays for wet-chemical synthesis with 5–level temperature gradients. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were applied to characterize Co–Ni bimetallic powder materials synthesized under 100 different reaction conditions. X-ray photoelectron spectroscopy (XPS) was conducted to confirm the oxidation state of the products. This platform not only enables one-step determination of the minimum reaction temperature required for a wet-chemical system but also provides a significant increase in efficiency compared with the traditional wet-chemical approach. The microfluidic-based composition and temperature controlling platform shows promise in facile, efficient, and low-cost HT wet-chemical synthesis of materials.

An ecofriendly nanocomposite of bacterial cellulose and hydroxyapatite efficiently removes lead from water

An environmentally friendly nanocomposite adsorbent composed of two renewable biomaterials, bacterial cellulose (BC) nanofibrils and hydroxyapatite (HA) nanocrystals, was synthetized by an in situ wet chemical precipitation technique, using clam shell biowaste as feedstock. HA nanocrystals embedded in an ultrafine BC network were confirmed and characterized trough different instrumental techniques (SEM, FTIR, XRD, EDS, surface charge and BET analysis), describing its nanostructure, chemical composition and thermal stability. The adsorptive removal of lead ions by the nanocomposite was investigated through batch experiments conducted under different pH, contact times and Pb(II) initial concentrations, proving that the process was highly favorable according to the Langmuir isotherm model (monolayer adsorption) with chemisorption as the main mechanism and kinetic data obeying a nonlinear pseudo-second order kinetic model. The developed nanocomposite showed a strong removal capacity of Pb(II) both in batch experiments (192 mg/g) and packed-bed column systems (188 mg/g), placing this new nanocomposite among top-performing BC-based biomaterials for lead removal.

Synthesis and structural characterization of Ca12Ga14O33

Ca12Ga14O33 was successfully synthesized using a wet chemistry technique to promote the homogenous mixing of the Ca and Ga cations. Rietveld refinements on X-ray and neutron powder diffraction data confirm that the compound is isostructural to Ca12Al14O33, however, with a significantly larger lattice parameter allowing for the cages that result from the framework arrangement to expand. In naturally occurring Ca12Al14O33, the mineral mayenite, these cages are occupied by O2− anions, however, experimental studies exchanging the O2− anions with other anions has led to a host of applications, depending on the caged anion. The functional nature of the structure, where framework distortions coupled with cage occupants, are correlated to electronic band structure and modifications to the framework could lead to interesting physical properties. The phase evolution was tracked using thermogravimetric analysis and high temperature X-ray diffraction and showed a lower formation temperature for the Ca12Ga14O33 analogue compared to Ca12Al14O33 synthesized using the same wet chemistry technique. Analyzing both X-ray and neutron powder diffraction using the Rietveld method with two different starting models results in one structural model, with one Ca position and the caged O on a 24d special position, being preferred.

Deposition of Cell Culture Coatings Using a Cold Plasma Deposition Method

Collagen coatings were applied onto polystyrene microplates using a cold atmospheric pressure plasma process. The coatings were compared to standard wet chemical collagen thin films using microscopy, surface energy, infra-red spectroscopy, electrophoresis, and cell culture techniques. Thin films were also deposited on gold electrodes using both coating methods and their structural and barrier properties probed using cyclic voltammetry. While the wet chemical technique produced a thicker deposit, both films appear equivalent in terms of coverage, porosity, structure, and chemistry. Significantly, the cold plasma method preserves both the primary and secondary structure of the protein and this results in high biocompatibility and cell activity that is at least equivalent to the standard wet chemical technique. The significance of these results is discussed in relation to the benefits of a single step plasma coating in comparison to the traditional multi-step aseptic coating technique.

Non-enzymatic simultaneous detection of acetylcholine and ascorbic acid using ZnO·CuO nanoleaves: Real sample analysis

A facile wet-chemical technique used to prepare the zinc oxide doped copper oxide nanoleaves (ZnO·CuO nanoleaves) in alkaline phase. ZnO·CuO nanoleaves were examined using a variety of conventional techniques for example UV–Visible, FTIR, XRD, FESEM equipped XEDS, and XPS. A non-enzymatic sensor was prepared with modification of a slightly deposited of ZnO·CuO nanoleaves onto a flat GCE, which fabricated through a conducting nafion polymer matrix in order to detect selective acetylcholine and ascorbic acid simultaneously. Analytical performances such as sensitivity, LOD, LOQ, LDR, and durability of the selective acetylcholine and ascorbic acid sensors were examined through a conventional current–voltage method. Calibration graphs of acetylcholine and ascorbic acid sensors were found linear (R2 = 0.9049 and 0.9201) over a good concentration range (100.0 pM–100.0 mM) respectively. Sensitivity (317.0 and 94.94 pAμM-1cm−2), LOD (14.7 and 12.0 pM), and LOQ (490.0 and 367.0 mM) of acetylcholine and ascorbic acid sensors were calculated correspondingly from the slope of the linear portion of calibration graph. Preparation of ZnO·CuO nanoleaves using wet-chemical technique is an excellent approach for the advancement of nanomaterial based on sensor development in support of enzyme free detection of biological molecules for the safety in healthcare and biomedical fields. This expected sensor applied for the specific determination of acetylcholine and ascorbic acid in real samples (Human, mouse, and rabbit serum, orange juice, and urine) and found satisfactory and acceptable results.

The adsorption of HEC and PVA as surfactants on SrTiO3 surface: A theoretical, experimental and applied investigation

Surfactants at solid/liquid interface could effectively improve the wettability of the liquid to the solid. Both the atomic force microscope (AFM) and theoretical calculations were applied to illustrate the mechanisms of behaviors of nonionic polymer surfactants represented by hydroxyethyl cellulose (HEC) and polyvinyl alcohol (PVA) at the solid/liquid interface of surfactant-assisted Pechini sol-gel method. The results clarified that the contact angles of surfactant-added sol reduced from64.92° ± 0.42° to 44.04° ± 0.37° and 48.53° ± 0.52° and the surfactants adsorbed on the solid in the form of disk shape, of diameter d = 500 nm and 100 nm for HEC and PVA, respectively. In addition, the adsorption energies between the oxygen atoms of the hydrophilic groups and the metal ion sites of the solid surface are -0.13 eV atom−1 for HEC and -0.04 eV atom−1 for PVA, respectively, indicating that the ion paring played a crucial role in improving the wettability of the sol to the solid. Furthermore, Bi-based superconductors with various morphologies could be prepared using surfactant-assisted Pechini sol-gel method with excellent crystallinity and transition temperatures of ∼70 K, exhibiting potential prospect in the preparation of functional oxide materials with different morphologies by wet-chemical technique.

Optoelectronic properties of facile synthesized orthorhombic cesium lead bromide (CsPbBr3)

CsPbBr3 has been synthesized via a wet chemical technique instead of colloidal hot injection route. Crystalline structure and chemical composition of the material have been assured by Rietveld refinement and energy dispersive X-ray spectroscopy. Photoresponse capability of CsPbBr3 nanocrystal in cubic phase has been already explored. Here, intrinsic optoelectronic properties of orthorhombic CsPbBr3 have been investigated in detail. A prototype photodetector has been fabricated on a transparent conducting oxide-coated glass by using silver as the other electrode material. The photo-responsibility of CsPbBr3 arises due to the combined effect of electron–hole pair generation and trapping within material and recombination. The non-linearity of I–V characteristics clearly reveals the formation of well-established Schottky contact at perovskite–ITO junction. Responsivity of the detector increases from 1.4 to 1.73 mA W−1 after enhancing the irradiance from 25 to 100 mW cm−2 at 8 V bias voltages. Linear dynamic range has been accounted to study the linear photosensitivity of the device. In order to investigate the stability and reversibility, photocurrent has been measured under ON/OFF condition of frequency 20 s. The quantitative contribution of polycrystalline grain and grain boundary to charge mobilization has been evaluated by fitting the Cole–Cole plot under different solar intensities.

Evidence of large exchange bias effect in single-phase spinel ferrite nanoparticles

Sm3+ doped spinel cobalt ferrite nanoparticles with a generic formula CoSmxFe2−xO4 (x = 0.00, 0.06, 0.12 and 0.18) were prepared using wet chemical co-precipitation technique. The structural, optical, magnetic and dielectric characteristics of the samples were investigated carefully. The phase purity and growth of spinel cubic structure was verified by room temperature x-ray diffractograms. Mean crystallite size was observed within the range of 6 nm to 15 nm as calculated from Scherrer’s formula. A blue shift in the indirect optical band gap was noticed with increasing Sm percentage as observed in UV–vis spectra due to the nanosize effect. Superparamagnetic nature at 300 K was detected for all Sm doped ferrite samples. Field cooled (150 kOe) M-H loops obtained at 5 K revealed a large amount of exchange bias field (≈4 kOe) together with high coercivity for the sample having smallest sized particles. Dielectric responses of all samples showed that the hopping of electrons was the fundamental charge conduction mechanism and grain boundaries play a crucial role in determining the dielectric properties.

Synthesis and Studies of Electro-Deposited Yttrium Arsenic Selenide Nanofilms for Opto-Electronic Applications

Nanocomposite films grown by incorporating varying concentrations of Yttrium, a d-block rare-earth ion, into the binary chalcogenide Arsenic selenide host matrix is here presented. Films were grown via the wet-chemical electro-deposition technique and characterized for structural, optical, surface morphology, and photoluminescence (PL) properties. The X-ray Diffraction (XRD) result of the host matrix (pristine film) showed films of monoclinic structure with an average grain size of 36.2 nm. The composite films, on the other hand, had both cubic YAs and tetragonal YSe structures with average size within 36.5–46.8 nm. The fairly homogeneous nano-sized films are shown by the Scanning Electron Microscopy (SEM) micrographs while the two phases of the composite films present in the XRD patterns were confirmed by the Raman shifts due to the cleavage of the As-Se host matrix and formation of new structural units. The refractive index peaked at 2.63 within 350–600 nm. The bandgap energy lies in the range of 3.84–3.95 eV with a slight decrease with increasing Y addition; while the PL spectra depict emission bands across the Vis-NIR spectral regions. Theoretically, the density functional theory (DFT) simulations provided insight into the changes induced in the structure, bonding, and electronic properties. Besides reducing the bandgap of the As2Se3, the yttrium addition has induced a lone pair p-states of Se contributing nearby to Fermi energy level. The optical constants, and structural and electronic features of the films obtained present suitable features of film for IR applications as well as in optoelectronics.

Physio-chemical influence of high electron-phonon coupling induced by 120 MeV Ag9+ SHI irradiation on exfoliated MoS2 - PVA nanocomposite films for achieving remarkable electrical conductivity for potential application in organic electronics

Swift heavy ion (SHI) irradiation technology is known to enhance the optical, electronic, mechanical, and electrical properties in polymer nanocomposites by the virtue of electron-phonon coupling. In the present work, Molybdenum disulphide (MoS2), a two-dimensional metal dichalcogenide, has been exfoliated via liquid-phase exfoliation using N-methyl-2- pyrrolidone (NMP) as the solvent that yielded nanosheets of around 2–4 layers as depicted by HR-TEM images. MoS2 - PVA free-standing films were prepared by wet chemical technique i.e. solution casting method and irradiated by focussed high-energy Ag9+ ion beam at fluence range of 1E10 - 3E11 ions/cm2. As a consequence, the structural modification was observed by X-Ray diffraction studies that showed the shift of (002) plane of MoS2 while Raman studies indicated the decrease of degree of disorderness at fluence 1E10 ions/cm2. SHI irradiation has found to induce a two-order increase in the electrical conductivity yielding a 9.7 E-3 S/cm against that of the pristine films at 2.6E-5 S/cm. The enhanced conductivity is attributed to the induced dispersion and annealing of MoS2 nanosheets in the PVA matrix due to the interaction of 120 MeV Ag9+ ion beam irradiation as explained by Thermal spike model.

DyCrxFe(1-x)O3 nanoparticles prepared by wet chemical technique for photocatalytic applications

DyCrxFe(1-x)O3 (0 ≤ x ≥ 0.4) nanoparticles were prepared using facile chemical route. Structural and morphological evaluation was carried out using X-ray diffraction (XRD) and electron microscopy. Formation of orthorhombic DyFeO3 nanoparticles was confirmed by XRD with crystallite size of 9–10 nm. FESEM images revealed nearly spherical morphology of the fabricated nanoparticles. Energy dispersive X-ray (EDX) technique was employed to confirm the presence of Dy, Cr, Fe and O elements in DyCrxFe(1-x)O3 nanoparticles. FTIR studies illustrated the presence of characteristics stretching and bending vibrations. UV–visible spectroscopy was used to analyze the photocatalytic performance of the DyFeO3 and Cr-substituted DyFeO3 nanoparticles and optical band gap measurements. Photocatalytic activities of the prepared substituted and un-substituted DyFeO3 nanoparticles were conducted using three different dyes. These dyes were (i) methyl orange, (ii) rhodamine B and (iii) methylene blue. Lower band gap and higher photocatalytic performance was observed for Cr-substituted DyFeO3 nanoparticles with methylene blue dye.

Photocatalytic decomposition of A549-lung cancer cancer cells by TiO2 nanoparticles

A novel, less time consuming and cost ineffective Wet chemical technique (WCT) was used to synthesis TiO2 nanoparticles at relatively low temperature, in acidic pH, using Titanium tetra isopropoxide (TTIP) as a precursor. The synthesized nanoparticles were characterized by XRD, SEM, TEM, and Uv–Visible spectroscopy. The results shows that the particle size from 17 nm to 14 nm. The Uv–Visible spectra show that blue shift was observed in TiO2 nanoparticles. The TEM images revealed that all the particles were in nanometer size. The synthesized nanoparticles shows good photocatalytic activity and it decompose 85% of A549 (lung cancer) cells in 4 h reaction.

Investigation of structural and optical properties of ZnO thin films deposited on glass substrates by wet chemical sol-gel technique

Nickel doped ZnO (NZO) and undoped ZnO thin films were deposited by wet chemical sol-gel spin coating method and their optical and structural properties have in detail been investigated by X-ray diffraction and optical absorption measurements to observe the effect of doping with different values of Ni molarity. The NZO and undoped ZnO thin films showed a growing trend along the c-axis perpendicular to the substrate surface. The strong (002) diffraction peaks at 2θ = 35.743°, 35.836°, 35.840° and 36.041° were observed to belong to samples undoped ZnO, NZO (0.25%), NZO (0.50%) and NZO (0.75%) films, respectively. The band gap values have been calculated from the dependencies (2 vs hν) by extrapolating the straight lines to 2 = 0 and found as 3.2630 eV and 3.2820 eV for 0.75% NZO and undoped ZnO thin films, respectively.

Cobalt-oxide/carbon composites for asymmetric solid-state supercapacitors

A facile methodology has been adopted for the synthesis of cobalt oxide (Co3O4) by wet chemical technique followed by the calcination and prepared Co3O4/C composite for energy storage devices. Initially, SEM and XRD are carried out to analyze the surface characterizations of electrode material. The electrochemical properties of synthesized material has been investigated and the maximum specific capacitance of 567 F/g is achieved for Co3O4/C composite at 3 mV/s scan rate. Co3O4/C composite and activated carbon (AC) are sandwiching and separated with PVA-KOH-C gel electrolyte. The device has been examined at several scan rates and current densities demonstrating better performance with maximum energy density of 63 Wh/kg at 0.7 A/g. The capacitive retentivity is 82 % after 6000 charge/discharge cycles. The solid-state devices are showing a tremendous performance with high energy and power density and are safe to handle due to no seepage which can be utilized for the next generation.

Comparative study on structure, dielectric and electrical properties of cobalt- and zinc-substituted Mn3O4 spinels

In this paper, we report the comparative study of single-phase crystalline Mn3O4, CoMn2O4, and ZnMn2O4 spinels prepared by a wet chemical co-precipitation technique. The absence of impurity peaks in the X-ray diffraction pattern of all prepared spinels endorses the formation of highly pure and single-phase spinels with the tetragonal crystal structure. The highest intensity peak for Mn3O4 was observed at (211) direction plane, and the same was followed by CoMn2O4 and ZnMn2O4 with a slight decrease in the angle of diffraction. The microstructure features observed from scanning electron micrographs reveal irregular-shaped nanosized grains with an average grain size of ~ 100 nm. The dielectric studies carried out from room temperature to 500 °C show high dielectric loss at elevated temperatures endorsing better conducting behavior. The DC-conductivity measurement substantiates the negative temperature coefficient of resistance behavior where resistivity decreases with an increase in temperature. The activation energy calculated using Arrhenius relation was 0.58 eV for Mn3O4, whereas it is 1.1 and 1.4 eV for Co- and Zn-substituted Mn3O4 confirming semiconducting nature of substituted spinels at higher temperature region.

Performance of SrCo1–xIrxO3−δ (x = 0.10 and 0.15) Perovskites as Potential Cathode Materials for Intermediate-Temperature Solid Oxide Fuel Cells (IT-SOFC)

We have designed and synthesized by wet chemical techniques a family of excellent cathode materials to be used in intermediate-temperature solid-oxide fuel cell (IT-SOFC) devices based on SrCoO3−δ ...

Extraction Nanoparticles from Chicory for Cooling Purposes of Photovoltaic Solar Cell with Nanofluid

Chicory or the so-called in Egypt Al-serees is found in a large quantities of agricultural clover and vegetables. The present study investigates the methanolic extract 70% of Cichorium intybus L belonging to family Asteraceae. Data obtained from the elemental analysis revealed the presence of 23 elements. The major detected elements are Sodium) Na( 159.59 ppm, potassium )K( 19.29 ppm, Calcium )Ca( 8.68 ppm, Magnesium) Mg( 6.88 ppm and Aluminium )Al( 3.11ppm respectively. The metallic nanoparticles are traditionally synthesized by wet chemical techniques with potassium chloride. The formation of potassium chloride nanoparticles was confirmed by X-Ray Diffraction, (XRD). The XRD pattern indicates that the nanoparticles had cubic structure. The XRD analysis of potassium chloride (KCl) nanoparticles have five peaks at 28.39, 40.58, 50.25, 58.75 and 66.47 angles. At 28.39 = 2θ, the curve has the extra highest peak. The average crystallite size for KCl as observed from XRD spectral analysis was found to be 20 nm, which is in agreement with the Transmission Electron Microscpe (TEM) analysis. The Scanning Electron Microscope (SEM) analysis shows the spheric potassium chloride and other minerals nanoparticles.The potassium chloride and other elements nanoparticles may be used to improve the performance of photovoltaic solar cell. The selection of chicory (Al-serees ) is due to a cost effective and environmental friendly technique