Papers by Keyword: Platinum Nanoparticles

Abstract: In this paper, anodic oxidation of sulphite ions on skeletal nickel based platinum nanoparticles electrode (6 layers) in aqueous alkaline solution was investigated in order to find the relationship between kinetic parameters and sulphite concentration. The purpose of this research is both to understand the oxidation mechanism and determine optimal parameters for oxidation process. Electrochemical behavior of sulphite ions has been studied by cyclic voltammetry and linear polarization. Tafel method was used in order to determine kinetic parameters and electrochemical impedance spectroscopy studies were performed to confirm the oxidation mechanism. For a complete characterization of sulphite electrooxidation process chrono-electrochemical methods (chronoamperometry, chronopotentiometry, chronocoulometry) were used.

Abstract: The migration and accumulation of nickel (nNi) and platinum (nPt) nanoparticles (NPs) in loamy sand and loamy soils (Luvisols) occupying the largest area in the southeastern part of West Siberia, have been investigated. The experiments were made in situ. The loamy sand soils (Albic Lamellic Luvisol) were tested down to a depth of 55 cm to sorb 100% nNi and at least 71% nPt of their total introduced amount. The rest 29% nPt either penetrated below the depth of 55 cm, or moved laterally. The experimental results in loamy soils enormously differed. Thus, only 16 to 20% nPt and 8 to 10 % nPt migrated radially in the Albic Luvisol and adjacent Stagnic Luvisol, respectively, while the rest NPs shifted laterally. The differences between the loamy soils are associated with lesser biogenic porosity of the Stagnic Luvisol, and, as a consequence, with higher density. The NPs migration and sorption processes are related to the soil properties differentiation. The inverse correlation between the concentration of nPt sorbed in soil horizons and their density with R² = 0.67 has been established. NPs have shown high migrational ability with nNi to a lesser extent, and nPt to a larger extent. During a single introduction, these are able to penetrate depths of more than 1 m with both gravitational and capillary water.

Abstract: For the first time studied the influence of nickel nanoparticles (Ni NPs) on the integrated index of biological activity of humus soil horizons in subboreal forest after treating with a 5.0 mg/l dispersion of nanoparticles. Adding nickel nanoparticle dispersion into the soil was carried out in filtration columns. Treatment of humus soils with Ni NPs has been established to decrease total microbial number to 50 % - 65 % in CFU, stimulate nitrification in all soil samples and a suppression of nitrogen fixation in loam soils Model tests on agar media with pure cultures of Pseudomonas fluorescens and Candida sp. showed varied sensitivity of different systematic groups to nickel nanoparticles. No positive CFU decrease of Pseudomonas fluorescens was found. However, in respect to certain concentrations of Ni NPs in an experiment with Candida sp., a marked decrease of CFU was observed.

Abstract: We studied the influence of superfine materials on the rooting ability and development of softwood cuttings of Ribes nigrum. The inhibiting effect of the soil amended with ZnO and Pt nanoparticles at the concentration of 5 mg/kg of substrate on the rhizogenesis of black currant cuttings was stated. On adding the suspension of ZnO nanoparticles the rooting ability of cuttings decreased by 32.3 %, and under the influence of Pt nanoparticles – by 41.4 %. The decrease in the morphometric parameters of development of the cuttings’ above-ground part and roots (growth amount, number of cratches and leaves, number of roots and their length) was observed. The change in the biochemical composition of leaves in the cuttings was stated. In the replication with zinc oxide the concentration of chlorophyll in leaves significantly decreased by 21.8 %. Under the influence of Pt the concentration of flavonoids in leaves increased by 48.8 %.

Abstract: The research studies concentration effects and influence of nCeO₂, nZnO, nNi and nPt on photosynthetic pigments in Chlorella v. B. in conditions of homeostated lab cultivation. It was shown that dependency of the content of chlorophylls and carotenoids in chlorella cells on concentrations of nCeO₂, nZnO and nPt has non-linear dual-phase character. Growing concentrations of nNi in the culture solution caused monotone decrease of all photosynthetic pigments in chlorella cells. Adding 0.1 mg/L nZnO in the suspension caused a statistically significant increase of the chlorophyll a and b content (27.1 % and 64.2 % respectively) in comparison with the control sample. NPs Pt at 1 mg/L induced stimulating effect on chlorophylls a (17.4 % compared to the control) and b (23.6 % compared to the control) in chlorella cells. The number of carotenoids had a statistically significant decrease in chlorella cells by 25-70 % at high concentrations (1-10 mg/L) for all tested NPs.

Abstract: The exponential growth of nanoparticle-containing goods and waste of the recent years will lead unavoidably to nanomaterials entering environment, generating in local biota and abiotic environment, and potentially transmitting to man. Aerial and water transmission of nanoparticles eventually will cause its generation in soil and further transmission to plants and animals via food chains.

Abstract: A mild synthetic process using formic acid as the reduction agent was applied to prepare 40 wt% Pt/carbon aerogel (CA) electrocatalyst. The as-prepared sample was characterized by transmission electron microscopy (TEM) and electrochemical measurements. The results exhibit Pt nanoparticles with narrow particle size distribution are dispersed throughout carbon aerogel structure. Moreover, the Pt/CA catalyst has smaller Pt nanoparticle mean size than Johnson Matthey HiSpec^TM 4000 (JM4000). The electrochemical measurement results indicate that the Pt/CA catalyst with Pt loading of 40 wt% possesses similar electrochemical surface area (ESA) value and oxygen reduction reaction (ORR) activity as JM4000.

Abstract: A structure and morphology of the fabricated nanocomposite materials composed of carbon nanotubes and platinum nanoparticles is reported in the paper. High quality CNTs obtained in the CVD process with a long of 100-200 mm and diameter of 10-20 nm were used in the research. Raw CNTs did not contain metallic impurities or amorphous carbon deposits. An indirect method of bonding the earlier produced platinum nanoparticles to the surface of functionalised carbon nanotubes was used to produce carbon nanotubes – platinum nanoparticles system. The main aim of current research was structure and morphology investigation of obtained nanocomposite using Transmission Electron Microscopy (TEM), Scanning Transmission Electron Microscopy (STEM) and X-ray structure analysis (XRD).

Abstract: A structure of nanocomposite materials consisting of carbon nanotubes with a varying fraction of platinum nanoparticles (5, 10 and 20 wt %) is compared in the paper. High-quality CNTs obtained in the CVD process, 100-200 mm long with a standard deviation of below 20% and with a diameter of 10-20 nm, with a standard deviation of below 30%, were used in the research. Raw CNTs did not contain metallic impurities or amorphous carbon deposits. An indirect method of bonding the earlier produced platinum nanoparticles to the surface of functionalised carbon nanotubes was employed to deposit platinum nanoparticles onto the surface of carbon nanotubes. A full array of changes in the loading of carbon nanotubes’ surface with platinum nanoparticles was achieved as a result of the experiments performed, starting with homogenous deposition to the clearly developed large agglomerations of platinum nanoparticles. The studies carried out using scanning electron microscopy, transmission electron microscopy, scanning transmission electron microscopy and X-ray structural analysis have confirmed differences in the morphology, homogeneity and density of coating the carbon nanotubes’ surface with variedly concentrated platinum nanoparticles. Differences were also revealed in the structure of the newly formed nanocomposites. A nanocomposite with a 5% fraction of platinum nanoparticles demonstrates the best structure-related properties for the materials obtained.

Abstract: A Platinum nanoparticles modified Au electrode has been successfully fabricated by using an in situ growth method. In this method, the Platinum nanoparticles could be grown on the Au electrode surface via the one-step immersion into the mixture of H2PtCl6 (analytical grade, 1g/L), NaBH4 (analytical grade) and polyvinylpyrrolidone K30 (PVP, analytical grade). A certain amount of PVP was added into the reaction system to prevent the coagulation of the Platinum nanoparticles, which obtained by the chemical redox reaction of H2PtCl6 and NaBH4. The structures and morphologies of the Platinum nanoparticles were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) . The direct electrochemical behavior of ascorbic acid in 0.3 mol/L NaCl medium at the Platinum nanoparticles modified electrode has been investigated in detail. Compared to a bare Au electrode, a substantial decrease in the overvoltage of the ascorbic acid was observed at the Platinum nanoparticles modified electrode with oxidation starting at ca. 0.20 V vs. SCE (saturated KCl). At an applied potential of 0.18V, this modified electrode produced high and reproducible sensitivity to ascorbic acid and linear responses were obtained over a concentration range from 0.600 to 3.267 μmol/L with a detection limit of 1.9 nmol/L(S/N=3). The fabrication method of this sensor, which has highly sensitive, low working potential, and fast amperometric sensing to ascorbic acid, is simple and without using complex equipment. In addition, the sensor has been successfully used to detect ascorbic acid in real sample, thus is promising for the future development of ascorbic acid sensors.