Evaluation of reduced-graphene-oxide-supported gold nanoparticles as catalytic system for electroreduction of oxygen in alkaline electrolyte

Abstract

Chemically-reduced graphene-oxide-supported gold nanoparticles with a diameter, of 40-60 nm are considered here as catalytic materials for the reduction of oxygen in alkaline medium in comparison to analogous systems based on conventional Vulcan carbon carriers. Gold nanoparticles are prepared by the chemical reduction method, in which the NaBH4-prereduced Keggin-type phosphomolybdate heteropolyblue acts as the reducing agent for the precursor (HAuCl4). Polyoxometallate (PMo12O403) capping ligands stabilize gold nanoparticle deposits, facilitate their dispersion and attachment to carbon supports. Indeed, it is apparent from the independent diagnostic voltammetric experiments (in 0.5 mol dm (H2SO4)-H-3) that heteropolymolybdates form readily stable adsorbates on nanostructures of both gold and carbon (reduced graphene oxide and Vulcan). It is reasonable to expect that the polyoxometallate-assisted nucleation of gold has occurred in the proximity of oxygenated defects existing on carbon substrates. Under conditions of electrochemical diagnostic experiments (performed in 0.1 mol dm (3) KOH): (i) the phosphomolybdate adsorbates are removed from the interface as they undergo dissolution in alkaline medium; and (ii) the Au nanoparticles (Au loading, 30 mu g cm (2)) remain well-dispersed on the carbon as evident from transmission electron microscopy. High electrocatalytic activity of the reduced-graphene oxide-supported Au nanoparticles toward reduction of oxygen in alkaline medium is demonstrated using cyclic and rotating ring-disk voltammetric experiments. The latter system could also act as the active support for Pt nanoparticles during the reduction of oxygen. Among important issues are possible activating interactions between gold and the support, as well as presence of structural defects existing on poorly organized graphitic structure of reduced graphene oxide (as evident from Raman spectroscopy)

One-pot facile simultaneous in situ synthesis of conductive Ag–polyaniline composites using Keggin and Preyssler-type phosphotungstates

“…Proper distribution of molecular active particles of Keggin and Preyssler heteropoly anions in the PAni nanostructures introduces them as excellent candidates for heterogeneous catalysis applications with enhanced performances. 38 The optical properties of "AgNPs-PAni-Keggin" (Fig. 3a) and "AgNPs-PAni-Preyssler" nanocomposites ( Fig.…”

“…7 N 2 adsorption/desorption isotherms of (a) "AgNPs-PAni-Keggin" nanocomposite, and (b) "AgNPs-PAni-Preyssler" nanocomposite, along with the inset figure of BJH pore size distribution. Table 6 Parametric results from BET analysis for "AgNPs-PAni-Keggin" and "AgNPs-PAni-Preyssler" nanocomposites N 2 adsorption/desorption "AgNPs-PAni-Keggin" nanocomposite "AgNPs-PAni-Preyssler" nanocomposite BET surface area 38 AgNPs products. IR results conrmed the existence of HPW as dopant anions that facilitated the stabilization, reduction and distribution of spherical AgNPs in the PAni matrix.…”

Electrocatalytic Oxygen Reduction in Alkaline Medium at Graphene-Supported Silver-Iron Carbon Nitride Sites Generated During Thermal Decomposition of Silver Hexacyanoferrate

“…Because basic Fig. 6 Cyclic voltammograms recorded for catalytic films of (A) Ag/ GNP800-C, (B) FeCN x /GNP800-C, and (C) AgFeCN x /GNP800-C recorded in 0.1 mol dm −3 KOH (at 100 mV s −1 ) before (dashed lines) and after (solid lines) preconditioning (P) in 0.1 mol dm −3 HClO 4 physicochemical properties of GO samples considered here were described elsewhere [68], we limit our microscopic characterization to the basic TEM image of AgFeCN x /GO800 and present the electrocatalytic performance toward O 2 reduction only in comparison to AgFeCN x /GNP800. As evident from Fig.…”

Preparation and Application of Keggin Silicomolybdic acid Modified Electrode

“…They also play an important role in catalyzing many organic reactions, such as homogeneous or heterogeneous acid catalysis, redox catalysis, photocatalytic oxidation [33][34][35][36][37].…”