Papers by Keyword: Platinum

Abstract: The paper presents a method for the production of 1% platinum catalysts containing oxides of rare-earth elements (REE); it also dwells upon the results of analyzing such catalysts by scanning electron microscopy (SEM), x-ray diffraction analysis (XDA), and thermal analysis (DTA-TGA).

Abstract: Magnetic MnFe₂O₄ nanoparticles (MNPs) were fabricated and entrapped in amine-rich chitosan (CS) sorbents containing multi-walled carbon nanotubes (MWCNTs) or polyethyleneimine (PEI). Magnetic polymer composite sponges (MPCSs) and magnetic polymer composite fibers (MPCFs) were prepared through mixing each of MWCNT and PEI with MNPs-CS solution. The successful fabrication of MPCSs and MPCFs was confirmed through FTIR and VSM analyses. The as-fabricated MPCSs and MPCFs were used for adsorptive recovery of Pt (IV) from acidic solution. The maximum uptakes of Pt (IV) ions by the MPCSs and MPCFs were estimated to be 218.2 ± 8.3 and 371.4 ± 16.8 mg/g, respectively. Moreover, the Pt (IV)-loaded MPCSs and MPCFs were easily separated from aqueous solution under magnetic field after sorption process.

Abstract: Pt-C material was synthesized by arc-discharge method for application in creation of a gas diffusion electrode for an Al-air battery. The material was burned and mixed with graphite powder to replacement poor conductive carbon matrix, which closes Pt nanoparticles. Gas-diffusion electrodes produced by usage such materials have work characteristics of industrial level. Improving of work characteristic of gas diffusion electrodes is associated with increasing of electrical conductivity of carbon matrix which closes Pt nanoparticles. The arc discharge parameter dependence of structural and conductive properties of pure carbon material was studied, and it’s determined that the main parameter is buffer gas pressure. The carbon materials synthesized at pressure lower than 12 Torr have several times larger conductivity due to disappearance of the amorphous carbon layers and decreasing of contact resistance.

Abstract: Controlling the morphology of platinum (Pt)-based nanomaterials is an effective strategy to enhance their catalytic performance for a given reaction. Here we report the syntheses of bimetallic Au-Pt nanomaterials with spherical or dendritic morphologies by a seed-mediated growth method. In this route, the gold (Au) nanoparticles are firstly prepared as seeds in oleylamine, which are subsequently seeded the growth of regular or dendritic Pt shells at different Au/Pt molar ratios. The electrochemical measurements show that the core-shell Au-Pt nanodendrites have better catalytic activity than that of core-shell Au-Pt nanoparticles for methanol oxidation reaction due to their abundant atomic steps, edges, and corner atoms in the branched Pt shells.

Abstract: Two kinds of Pt/CeO₂ catalysts supplemented with NiO or CoO_x additives were synthesized by extractive-pyrolytic method and tested in glycerol oxidation processes. It was found that only NiO additive promotes Pt/CeO₂ catalysts activity and selectivity to glyceric acid. NiO promoted Pt catalysts activity depends on NiO composites’ calcination temperature, oxygen partial pressure, initial NaOH concentration, as well as temperature. Glycerol conversion increases along with increased oxygen partial pressure from1 to 6 atm and along with decreased glycerol/Pt molar ratio from 5000 to 300. It was found that presence of base is significant in the glycerol oxidation processes over NiO promoted Pt/CeO₂ catalysts, and optional NaOH initial concentration is 0.6 mol/L. The best yield of glyceric acid (68%) was reached in the presence of 4.8wt%Pt/5wt%NiO/CeO₂ (300 °C) catalyst, when temperature was elevated up to 70 °C.

Abstract: Silver-platinum (Ag-Pt) bimetallic nanoparticles (NPs) with varying mole fractions (1:1, 1:3 and 3:1) were prepared by co-reduction of hexachloroplatinate and silver nitrate with sodium citrate. Upon successful formation of monometallic and bimetallic (BM) core shell nanoparticles, cyclic voltammetry (CV) was used to characterize the NPs. The drop coated nanofilms on the GC electrode showed characteristic peaks of monometallic Ag NPs; Ag⁺/Ag⁰ redox couple as well as the Pt NPs; hydrogen adsorption and desorption peaks. Varying current trends were observed in the BM NPs ratios as; GCE/Ag-Pt NPs 1:3 > GCE/Ag-Pt NPs 3:1 > GCE/Ag-Pt NPs 1:1. Fundamental electrochemical properties such as; diffusion coefficient (D), electroactive surface coverage, electrochemical band gaps and electron transfer coefficient (α) and charge (Q) were assessed using Randles - Sevcik plot. High charge and surface coverage was observed in GCE/Ag-Pt NPs 1:3 accounting for its enhanced current. GCE/Ag-Pt NPs 3:1 showed high diffusion coefficient while GCE/Ag-Pt NPs 1:1 possessed high electron transfer coefficient, which is facilitated by its heterogeneous rate constant relative to other BM NPs ratios. Surface redox reaction was determined as adsorption controlled in all modified GCEs.

Abstract: An electrochemical method for determination of the platinum and palladium was suggested and developed in this study. The effect of accompanying elements on the electrochemical oxidation processes of platinum and palladium has been described. It has been shown that the determination of platinum and palladium is possible only after removal of sample components.

Abstract: Abstract. Some features of behavior and kinetic of the anodic processes for the platinum and Cu–Fe–Ni alloy in the KF–NaF–AlF₃–Al₂O₃ melts at 1025–1055 K have been studied by cyclic voltammetry and chronopotentiometry.The obtained results allowed us to conclude that mechanisms of the anodic processes at the platinum and Cu–Fe–Ni alloy are similar. Both mechanisms include the oxidation stage of electrode material. A rate of this stage is determined to depend significantly on the melt temperature.

Abstract: In spite of selectivity of platinum and rhenium stripping voltammetry analysis techniques, it is very difficult to identify them in the presence of other metals. This manuscript reports on the stripping voltammetric determination of platinum and rhenium in the presence of other metals. The effect of accompanying elements on the electrochemical oxidation processes of platinum and rhenium has been described. It has been shown that it is possible voltammetric determination of platinum and rhenium after removal of interfering matrix components of mineral raw materials at the stage of sample preparation.

Abstract: The technique of platinum (IV) determination in mineral raw materials with the application of stripping voltammetry has been proposed. The authors determined the registration conditions in the determination of the analytical signal Pt (IV): the composition of background electrolyte, the electrolysis potential. The graphite electrode impregnated with polyethylene was used as a working electrode. The use of stripping voltammetry applied to the assessment of the platinum content in geological objects was demonstrated.