Papers by Keyword: Chemical Deposition

Abstract: For the purpose of synthesizing 2D-Material–Magnetic nanocomposites, several new modifications of existing 2D-materials synthesis methods by exfoliation and chemical synthesis from liquid charge are developed. Using them, graphene (G), graphene oxide (GO), reduced graphene oxide (rGO) and hexagonal boron nitride (h-BN) matrix magnetic nanocomposites for the first time are obtained by coating or intercalation their nanoparticles with ferromagnetic iron (Fe) or ferrimagnetic iron oxide – magnetite (Fe₃O₄). These materials are prospective for variety of high tech applications. In particular, h-BN–Fe₃O₄ composite nanoparticles can serve for neutron-capturing boron isotope ¹⁰B effective delivery agents in BNCT (Boron Neutron Capture Therapy) of cancer as they allow the controlling by an external magnetic field targeting to tumor tissue.

Abstract: The mechanical properties of grinding-tools relies highly on adhesion between the abrasive particles and the bonding phase, generally composed of organic rubber or resin materials. The surface modification of abrasive particles represents an industrial alternative to improve the connection with the bonding phase material. However, increasing the roughness of abrasive particles is a challenging process because of their high chemical stability. In the present study, three different approaches are investigated to modify the surface of industrially used alumina abrasive particles. Chemical erosion under harsh acidic and alkaline conditions, and hydrothermal deposition of aluminium-based coatings were used for the surface modification of the abrasive particles. The chemical stability of alumina particles was demonstrated by the chemical etching while the succesufull surface deposition of AlOOH crystals modified the apparent roughness of the processed powder particles. Morphological changes after each treatment were studied by scanning electron microscopy and the phase composition was confirmed by X-ray diffraction.

Abstract: Cuprous Oxide (Cu₂O) is a semiconductor material with excellent photocatalytic properties, a broad range of applications, low fabrication costs, and is non-toxic. We concentrated on the impact of two different synthesis methods in this study. Cu₂O synthesis was carried out using two different techniques, which are chemical deposition and hot-soap method. The chemical deposition (CD) method used a copper sulfate pentahydrate precursor in a room temperature reaction. Hot-soap (HS) method employed copper acetylacetonate with reaction at higher temperature. The X-Ray Diffraction analysis reveals a sharp peak with a size of 53.8 nm and a broaden peak with a size of 26.24 nm for particles synthesized by (Cu₂O-CD) and (Cu₂O-HS), respectively. Using the Tauc Plot method, the band gap of Cu₂O-HS is estimated to be 2.65 eV and that of Cu₂O-CD to be 1.7 eV. Cu2O-HS emits a noticeable photoluminescence peak at 425 nm, whereas Cu₂O-CD emits no peaks in photoluminescence spectra analysis. These findings indicate that Cu₂O-HS has a high potential for use in photocatalytic mechanisms.

Abstract: The in situ chemical deposition of polypyrrole (Ppy) in presence of different concentrations of salicylic acid (SA) directly at copper 99.9% surface in ethanol solution using hydrogen peroxide as catalyst was studied. In all the concentrations, 50.0, 25.0, 12.5 and 6.25 mmol L^-1 the polymerization was possible. The layer formed on the copper surface showed to be adherent and homogeneous. Its morphology presented as compact microspheres. The polarization curves showed a positive displacement in the corrosion potential of copper with undoped Ppy when compared to the polished copper surface. Copper surfaces containing doped Ppy-SA also showed an increase to the positive direction in the corrosion potential and the corrosion current density decreases more sharply in the presence of SA as dopant. These results indicated that Ppy+SA can act as a protective layer on copper surface and improve the corrosion protection. The protection efficiency of the coating was Cu surface < Cu+Ppy < Cu+Ppy+SA 50.0 < Cu+Ppy+SA 25.0 < Cu+Ppy+SA 12.5 < Cu+Ppy+SA 6.25 mmol L^-1.

Abstract: Herein, Ag-anatase photocatalysts were synthesized though chemical reduction method under room temperature by using PVP and NaBH₄ as stabilizer and strong reducing agent, respectively. The prepared photocatalysts were characterized by the following technique: XRD, SEM, HR-TEM, EDX, and UV-Vis-NIR. The photocatalytic performance of 0.05 g of photocatalysts were performed under UV irradiation within 1 h by using 10 mg/L of rhodamine B as the representative of organic pollutant. The results demonstrated that the optimum Ag loading contents were 2 %wt (2-ST) which can degrade rhodamine B up to 98.54%. Therefore, the photocatalytic performance of bare anatase could be enhanced by deposited Ag nanoparticles. Further, this prepared Ag-anatase could be suitable for environmental application.

Abstract: Pyrrole was successfully polymerized on copper surface in ethanol solution using hydrogen peroxide as catalyst to generate an adherent and homogeneous polypyrrole (PPy) coating. The PPy was formed of clusters composed of small spherical grains. The layer has remained stable when immersed in 0.1mol L^-1 NaCl for 7 days, which indicated that the copper-PPy arrangement is stable in corrosive environment. The polarisation curves showed that the PPy layer can promote a positive displacement in the corrosion potential compared to the value of the uncoated copper. It also was observed that the corrosion current density decreases sharply in the presence of the lauric acid as dopant. These results indicate that PPy-lauric acid can act as a protective layer on copper and improve the overall corrosion performance.

Abstract: Amorphous Со-Р and Co-Ni-P films fabricated by chemical deposition under the same conditions are investigated. It is demonstrated that the phosphorous content in the Co-Ni-P exceeds that in the Со-Р films by 1.5−2%. The atomic force microscopy analysis of the surface morphology shows that incorporation of Ni atoms in the Со−Р alloy leads to coarsening of grains due to the higher rate of deposition of Ni atoms as compared with the rate of deposition of Со atoms. The reduction of the dispersion of the polar Kerr effect saturation field in the Со-Ni-P films is attributed to ordering of Сo-Ni atomic pairs.

Abstract: Nickel hydroxide nanoporous electrochromic thin films were obtained by chemical bath deposition method using nickel nitrate in two different formulations. In one case, ammonium hydroxide controlled the precipitation of the β-Ni (OH)₂ phase through the formation of coordination compounds. In the second case, the decomposition of urea yielded the α-Ni (OH)₂ phase. After thermal annealing in air in between 250 and 300 °C, the electrochromic behavior of the films was examined by cyclic voltammetry and single wavelength transmittance. The optical contrast and structural transformations between colored and bleached states of the samples were studied by ex-situ optical transmittance, X-ray diffraction, as well as Raman and infrared reflectance spectroscopies. The α-Ni (OH)₂ films showed higher optical contrast and reversibility, properties associated with their porous morphology which is revealed by scanning electron microscopy studies.

Abstract: Coercivity of amorphous Co-P single-layer and trilayer films fabricated by chemical deposition has been investigated. It has been established that the thickness dependences of the coercivity for isotropic and anisotropic films are different. Data on the coercivity variation with a nonmagnetic spacer thickness and a number of magnetic layers in the trilayer films are reported. The results obtained are analyzed with regard to the features of the induced anisotropy in amorphous ferromagnetic films and the magnetic coupling between magnetic layers in sandwich structures.

Abstract: Nickel oxide/carbon nanotubes (NiO/CNTs) composite materials for supercapacitor are prepared by chemically depositing of nickel hydroxide onto CNTs pretreated by ultrasonication and followed by thermal annealing at 200-300°C. A series of NiO/CNTs composites with different weight ratios of CNTs and different annealing temperature are synthesized via the same route. The scanning electron microscope (SEM) images show that the nucleation of the nickel hydroxide formed on the outer walls of CNTs due to ultrasonic cavitations, and then nickel oxide coated uniformly on the outer surface of the individual CNTs after thermal annealing. The NiO/CNTs electrode presents a maximum specific capacitance of 254 F/g as well as a good cycle life in 2 M KOH electrolyte. The good electrochemical characteristics of NiO/CNTs composite can be attributed to the three-dimensionally interconnected nanotubular structure with a thin film of electroactive materials.