Papers by Keyword: Electrochemical Characterization

Abstract: We presented here the development of an immunosensor based on graphene nanoplatelets-modified screen printed carbon electrode (SPCE) with incorporated rabbit IgG on the amino functionalized surface area. In order to improve sensitivity of working electrode, graphene-nanoplatelets solution was fabricated onto surface carbon working electrode. The effect of different (3-aminopropyl) triethoxysilane (APTES) concentrations (0.125, 0.5, 2 and 8% (v/v)) and incubation time of silanization (30, 60 and 90 min) were studied and compared. An electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to characterize our immunosensor based. It is showed that the optimum APTES concentration which provides higher surface coverage and electron transfer rate was 2% concentration (v/v) at 60 min of incubation time. The modified surface was then evaluated by measuring immobilized rabbit IgG via indirect assay using horseradish peroxidase labelled secondary antibody. The optimum detection immobilized IgG was 0.05 mg/mL. These results indicate the potential for amino functionalized graphene nanoplatelets-modified SPCE in detecting protein biomarkers.

Abstract: The investigation of the corrosion resistance of Ti6Al4V alloy components produced by additive technology is still lacking in the literature. This paper aims to study the electrochemical behaviour of Ti6Al4V components fabricated by laser powder-bed fusion additive manufacturing process. The metallographic analysis was carried out by an optical microscope. The electrochemical behaviour has been evaluated in 3.5 wt. % of natural aerated NaCl aqueous solution by potentiodynamic polarization test. The results have been compared to a conventionally manufactured Ti6Al4V component. The typical martensitic structure has been shown by the additive manufactured sample. As expected, the metallographic analysis revealed a martensitic microstructure. The electrochemical tests carried out on the surface of the as-received additive manufactured specimen showed an influence of its morphology on the values of passive current density, higher than that recorded for the conventionally manufactured sample, used as the control. After mechanical polishing, the electrochemical tests were repeated on the "bulk" of the samples. The open circuit potential values were higher than the value recorded for the conventionally manufactured sample. The conditions of the additive process affect the corrosion resistance of the components due to the roughness of the surface and to the microstructure created.

Abstract: All precipitate morphologies in Mg-8.8%Hg-8%Ga alloy for a range of aging temperatures are investigated in details using SEM, TEM and OM. The results show that Mg21Ga5Hg3 is the dominant precipitate in Mg-8.8%Hg-8%Ga alloy and precipitates in dispersed particles. This study elaborates on the morphological evolution of Mg21Ga5Hg3 precipitates as a function of aging time and temperature.

Abstract: The boron-doped diamond film electrode grown on tantalum substrate (BDD/Ta) was prepared by hot filament chemical vapor deposition (HFCVD) technique. The morphology and quality of BDD/Ta film electrode were investigated by SEM and Raman spectroscopy respectively. The electrochemical behavior of the BDD/Ta film electrodes in Na₂SO₄ solution was also investigated by cyclic voltammetry and the window potential of BDD/Ta film electrode in Na₂SO₄ solution is of 4.1V, the hydrogen and oxygen evolution potentials are of-1.8V and +2.3V respectively. The characteristic measurements of BDD/Ta film electrode and its application to degradation of high concentration organic wastewater indicated that BDD/Ta film electrode have a series of advantages, including high overpotential for oxygen revolution, high current efficiency, good removal of chemical oxygen demand (COD).

Abstract: We propose a novel preparation technology of CNTs modified electrode. CNTs are mixed with polymer into homogenate by mechanical ball grinder; spin homogenate into composite film; solidify and polish composite film; chemical etch polymer partly from the surface of the composite film, in order to keep part of the CNTs be inserted in polyimide and the remainder outside of film, then CNTs modified electrode can be got. The morphologies of CNTs modified electrode are observed by field emission scanning electron microscopy (FESEM). The application of CNTs modified electrode in alum solution battery is demonstrated. Cyclic voltammetry of CNTs modified electrodes in V4+ solution is discussed.

Abstract: The present paper focuses on a nanostructured SnCo alloy electrochemically prepared by template method in view of its use as anode material alternative to graphite in lithium-ion batteries. The fabrication of SnCo nanowire arrays was carried out by potentiostatic co-deposition of the two metals by using nanostructured anodic alumina membranes as template. Electrochemical tests on lithiation-delithiation of these SnCo electrodes in conventional organic electrolyte (EC:DMC LiPF6) at 30°C showed that their specific capacity was stable for about the first 12 cycles at a value near to the theoretical one for Li22Sn5 and, hence, progressively decayed.

Abstract: Solid Oxide Fuel Cells (SOFCs) are gaining more and more importance as auxiliary power units (APU), e.g. for passenger cars, trucks and airplanes. In this context, the main challenge is the development of SOFC stacks, which fulfill the strong requirements for mobile applications. These are a low weight, a low volume, and a high power density with reformate gases but also low long term degradation rates. The paper presents results of investigations of SOFC short stacks for mobile applications. Therefore, a light weight stack design was developed in an industrial consortium in cooperation with the German Aerospace Center (DLR) in Stuttgart and the Research Center Jülich (FZJ). The SOFC stacks were operated at different temperatures, varying fuel gas compositions and different fuel gas flow rates. The short stacks were electrochemically characterized mainly by long-term measurements, by current-voltage measurements and by impedance spectroscopy. The fuel utilizations and the power densities were determined. In order to analyze the uniformity inside the stacks, the electrochemical behaviour of the individual cassettes were analyzed and compared to each other. Finally, the degradation rates and the degradation mechanisms were determined from the long-term measurements.

Abstract: The surface topography of Titanium implants modulates bone response and implant anchorage. For this reason great efforts yet will be made for new surface refinements. In this work Ti samples were surface structured by corundum blasting firstly and then chemically etched to remove the remaining corundum particles and further surface structuring. In following steps these samples were electrochemically etched or additionally structured and coated with various micro-plasma processes. As result we got various typical surface structures in micro- and nanoscale and also different coating layers in dependence on the composition of the electrolyte for the micro-plasma process. In all steps the properties of the modified Ti surfaces were characterised mechanically by surface profiling, optically by SEM and electrochemically by CV- (for testing the corrosion parameters), CA- (to give the enlargement of the real surface) and EIS-measurement in range of 100 kHz to 1 mHz (to give a survey of the changing of surface capacities and structures). A comparison of the measuring results demonstrated their reliability.