AuFe electrodeposits onto a rotating disk electrode were examined to assess the composition and current efficiency behavior when citric acid, ascorbic acid, or a combination of both is present in the electrolyte. Nanowires were subsequently fabricated with pulsed current deposition to create compositionally, multilayered Au/FeAu nanowires. The FeAu layer of the nanowires was porous in a citrate electrolyte, but the porosity decreased with the addition of ascorbic acid in the electrolyte. Comparatively higher side reaction partial current densities (i sr ) in the citric acid electrolyte generated local alkaline conditions, inducing the chemical precipitation of Fe ions in the form of iron oxide nanoparticles inside the recess, which manifested as the regions of high porosity. Nonporous layers observed in the ascorbic acid bath, in combination with decreased i sr and increased current efficiency of the deposits, suggested that a similar mechanism of Fe precipitation inside the nanorecess is less likely.

http://jes.ecsdl.org/content/157/6/D370.full.pdf

Influence of Citric and Ascorbic Acids on Electrodeposited Au/FeAu Multilayer Nanowires

Environmentally clean hydrogen fuel represents a number of advantages over popularly utilized petroleum-based derivatives. Among alternative technologies, hydrogen can be generated by direct electrolysis of water upon irradiating a semiconductor material with light of energy greater than its energy band gap. A strategy to improve the photocatalytic efficacy of bare semiconductors and promote the sluggish kinetics of the oxidation reaction has been the incorporation of noble metals onto their surface. In particular, the Au-TiO2 system has been effective at enhancing and shifting the photoactivity to irradiation of longer wavelengths through relatively more efficient electron transfer processes involved in redox reactions. Main drawbacks that limit the applicability of Au-TiO2 composites are aging and/or deactivation effects arising from prolonged exposure to irradiating light. A novel approach to circumvent such effects, improve the stability of the composite towards atmospheric conditions and achieve longlasting activity is presented in this study. The design involved incorporation of solid-state Fe in galvanic contact with Au(s), which theoretically induces a deactivation resistance on Au(s), owing to differences in nobility and electromotive potential (emf) of the electrochemical reactions involved (i.e. Fe(s) → Fe 2+ + 2e and Au 3+ + 2e → Au). A preferential natural corrosion of the sacrificial less noble Fe serves as protection by oxidizing first at the expense of protecting the nobler Au from corrosion. In the present study, Fe(s) was tailored in galvanic contact to Au(s) in the form of Au/AuFe multilayered nanowires, which were fabricated electrochemically by means of a squarewave pulsed current scheme from a cyanide-free electrolyte. Variations in porosity and Fe content of the alloy layer were controlled via the deposition conditions and the type of complexant species present in the electrolyte. The fabricated Au/FeAu multilayer nanowires were subsequently integrated on electrosynthesized TiO2 to form the composite and its photocatalytic potential for the water splitting reaction assessed by means of a step in illumination, cyclic voltammetry and impedance modulated photocurrent spectroscopy (IMPS). The efficacy of Fe at preventing catalyst deactivation, as well as the effect of variations in porosity and Fe content of nanowires integrated onto TiO2, on the catalytic performance, were assessed.

https://repository.library.northeastern.edu/files/neu:653/fulltext.pdf

ELECTRODEPOSITED Au/FeAu POROUS NANOWIRES FOR ENHANCED CATALYTIC ACTIVITY AND STABILITY OF REACTIONS ON TITANIA

Biamperometric determination of copper, silver and gold with ascorbic acid

Amperometric determination of mercury and cadmium alone or in a binary mixture with hydrazine sulfide as titrant

Methode utilisant comme electrolyte de base un melange de tartrate d'ammonium et d'ammoniaque a pH≃9. Dans ces conditions, Cd reagit seulement apres que tout le mercure a ete precipite. Precision comparable a celle de la methode classique

/pdf/amperometric-determination-of-mercury-cadmium-alone-or-in-a-t7uo5kzxtz.pdf

S. N. Joshi

Papers

Biamperometric determination of copper, silver and gold with ascorbic acid

Amperometric determination of mercury and cadmium alone or in a binary mixture with hydrazine sulfide as titrant

Amperometric Determination of Mercury & Cadmium Alone or in a Binary Mixture with Hydrazine Sulphide as Titrant