María A. Montero

Preparation of gold nanoparticles supported on glassy carbon by direct spray pyrolysis

A method for the preparation of gold nanoparticles supported on glassy carbon by direct spray pyrolysis in air at low temperature is presented. The procedure is based on the property of some gold salts which, unlike many other metal salts, decompose by heating at low temperature to produce metallic gold and gaseous species which depend on the salt nature. In the case of the present work, HAuCl4.nH2O was used, which decomposed to solid Au and gaseous H2O and chlorine containing compounds such as HCl and Cl2. This behaviour was verified by thermogravimetric analysis and X-ray diffraction. The gold nanoparticles supported on a glassy carbon electrode were obtained by the impact of HAuCl4 solution droplets generated by an ultrasonic atomizer. These droplets are directed through a nozzle towards the glassy carbon substrate located on a stainless steel block heated by electrical resistance. The supported gold nanoparticles were electrochemically characterized by cyclic voltammetry in acid solution and the surface morphology was characterized by SEM and AFM operated in the tapping mode.

A Simple Method to Establish the Relationship Between the Equilibrium Polarization Resistance and the Elementary Kinetic Parameters of an Electrocatalysed Reaction

AbstractA simple and rigorous methodology to establish the relationship between the faradaic equilibrium polarization resistance of an electrocatalytic reaction with the elementary kinetic parameters involved in the reaction mechanism is proposed. It was derived through an alternative method, which avoided the differentiation of the corresponding current-overpotential dependence. This formalism includes the cases where both, reactants and products, exhibit diffusion contributions. It is demonstrated that the equilibrium polarization resistance is the sum of both, faradaic and diffusion, contributions. Each diffusion term has a linear variation with the inverse of the limiting diffusion current density of the species involved. This behavior was exemplified with two different experimental data sets for the hydrogen electrode reaction, obtained on a rotating disc and microelectrodes, respectively. Graphical AbstractExperimental equilibrium polarization resistance is the sum of faradaic (Rpo

Kinetics of the hydrogen oxidation reaction on nanostructured rhodium electrodes in alkaline solution

{R}_p^o

Hydrogen oxidation reaction on platinum nanoparticles: Transition between mechanistic routes

) and diffusion (Rpd

The evaluation of the polarization resistance in a tubular electrode and its application to the hydrogen electrode reaction

{R}_p^d

Effects of the electrochemically grown hydrous oxide on the hydrogen electrode reaction on iridium electrode

) contributions. A simple and novel methodology is presented for the derivation of the relationship between Rpo