A catalytic platinum–ruthenium–polyaniline electrode for methanol oxidation

Polyaniline films prepared on Au wires were employed as substrates to deposit Pt and/or Ru using a potential-programmed perturbation. Different compositions of Pt and Ru ions in acid electrolyte were employed to decorate the electrodes. The atomic percentages of Pt and Ru on Pani were determined by EDAX and particle size and distribution by SEM. The catalytic activity was tested for adsorbed CO and CH3OH electrooxidation. Nanoparticles of Pt–Ru with different Pt–Ru contents were obtained and characterized for each reaction.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Catalytic polyaniline-supported electrodes for application in electrocatalysis

Polyaniline (Pani) films prepared on Au wires were employed as substrates to deposit Pt, Pt-Ru, Pt-Os, Pt-Mo and Pt-Ru-Os or Pt-Ru-Mo by using appropriate working solutions and a potential-programmed perturbation. The atomic percentages of the different metals on Pani were determined by EDAX and their particle size and distribution by SEM. The catalytic activity was tested for adsorbed CO and CH₃OH electrooxidation. Accordingly, the best binary and ternary metal combination resulted in Pt-Ru and Pt-Ru-Os.Facultad de Ciencias ExactasInstituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

The influence of carbon monoxide on the voltammetric behaviour of nickel in acid solutions

The voltammetric behaviour of nickel in acid solutions is considerably modified by the presence of CO. As in plain acid the voltammogram also exhibits two main anodic peaks, but in this case, the adsorption of CO on the nickel surface shifts the metal electrodissolution to more positive potentials, and increases the contribution of the second electrooxidation current peak at the expense of the first one. The latter is the main peak in CO-free acids. The presence of CO adsorbates also decreases the charge of the Ni(OH)2/NiOOH redox couple in alkaline solutions. The potential shift of the nickel electrooxidation reaction in acids follows the trend which is expected from the energy difference between CO and H2O adsorption on nickel in the gas phase.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Catalytic polyaniline-supported electrodes for application in electrocatalysis

Polyaniline (Pani) films prepared on Au wires were employed as substrates to deposit Pt, Pt-Ru, Pt-Os, Pt-Mo and Pt-Ru-Os or Pt-Ru-Mo by using appropriate working solutions and a potential-programmed perturbation. The atomic percentages of the different metals on Pani were determined by EDAX and their particle size and distribution by SEM. The catalytic activity was tested for adsorbed CO and CH₃OH electrooxidation. Accordingly, the best binary and ternary metal combination resulted in Pt-Ru and Pt-Ru-Os.Facultad de Ciencias ExactasInstituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Effect of Water Content in the Gas Diffusion Layer of H2/O2 PEM Fuel Cell

The heart of a fuel cell is the membrane-electrode assembly consisting of two porous electrodes, where the electrochemical reactions take place, and the ionomer conductive membrane, which allows the proton exchange from the anode to the cathode. The porosity of the electrodes plays an important role in the fuel cell performance. One of the drawbacks presented by the porous electrodes is the accumulation of water in their structure, which implies a hindrance for the reactive gas transport to reach the catalytic reactive sites. In this paper, a mathematical model of a porous electrode, assuming single pores with uniform distribution, is introduced to determine the influence of water accumulation in the electrode on the fuel cell performance under different operating conditions. It is demonstrated that at low current densities, water accumulation has no effect in the fuel cell behavior, whereas at high current densities its performance is severely affected

Methanol Electrooxidation on Pt-Ru Catalysts Dispersed in Conducting Polyaniline Films

Methanol electrooxidation was investigated on tailored Pt-Ru-polyaniline catalysts prepared applying dynamic potential routines. The electrodes characterized by SEM, EDX and TEM present a uniform distribution of metal particles about 100 nm in size, composed of Ru and Pt on the fibrous polymer matrix. The effect of concentration in the range 0.05-1 M and temperature in the range 20 to 60 °C on the methanol electrooxidation rate was determined. The apparent activation energy depends on the catalyst Ru content.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

The influence of carbon monoxide on the voltammetric behaviour of nickel in acid solutions

The voltammetric behaviour of nickel in acid solutions is considerably modified by the presence of CO. As in plain acid the voltammogram also exhibits two main anodic peaks, but in this case, the adsorption of CO on the nickel surface shifts the metal electrodissolution to more positive potentials, and increases the contribution of the second electrooxidation current peak at the expense of the first one. The latter is the main peak in CO-free acids. The presence of CO adsorbates also decreases the charge of the Ni(OH)2/NiOOH redox couple in alkaline solutions. The potential shift of the nickel electrooxidation reaction in acids follows the trend which is expected from the energy difference between CO and H2O adsorption on nickel in the gas phase.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Nanocatalysts for ethanol oxidation: Synthesis and characterisation

Carbon-supported binary PtSn/C and ternary PtSnNi/C catalysts were prepared for the electro-oxidation of ethanol. The carbon-supported nanoparticles were synthesised by employing a modified polyol methodology and characterised in terms of structure, morphology and composition by using XRD, EDX and TEM techniques. Their electrocatalytic behaviour for ethanol oxidation (EO) was investigated by employing a disccomposite electrode covered by a thin layer of catalyst imbedded in a Nafion polymer electrolyte film. An enhancement of the EO through a negative shift of the onset oxidation potential and higher current density at constant potentials were observed on the PtSnNi/C electrodes as compared to those for PtSn/C electrodes. The temperature was changed in the range 40 °C ≤ t ≤ 80 °C, and the variation of the activation energy calculated by linear regression of the Arrhenius plots.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Nanocatalysts for ethanol oxidation: Synthesis and characterisation

Carbon-supported binary PtSn/C and ternary PtSnNi/C catalysts were prepared for the electro-oxidation of ethanol. The carbon-supported nanoparticles were synthesised by employing a modified polyol methodology and characterised in terms of structure, morphology and composition by using XRD, EDX and TEM techniques. Their electrocatalytic behaviour for ethanol oxidation (EO) was investigated by employing a disccomposite electrode covered by a thin layer of catalyst imbedded in a Nafion polymer electrolyte film. An enhancement of the EO through a negative shift of the onset oxidation potential and higher current density at constant potentials were observed on the PtSnNi/C electrodes as compared to those for PtSn/C electrodes. The temperature was changed in the range 40 °C ≤ t ≤ 80 °C, and the variation of the activation energy calculated by linear regression of the Arrhenius plots.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Influence of carbon monoxide, ethylene, acetylene, allyl alcohol and propargyl alcohol on nickel electrodissolution in aqueous sulfuric acid solution

The influence of carbon monoxide, ethylene, acetylene, allyl alcohol and propargyl alcohol on nickel electrodissolution in aqueous 0.5m H2SO4 was studied after the adsorption equilibrium of each of these species at a fixed potential and room temperature had been attained. The hindrance of nickel electrodissolution by carbon monoxide is greater than that resulting from double and triple C-C bond compounds at the same concentration in the solution. Corrosion current, corrosion potential, the amount of dissolved nickel at a constant potential and steady hydrogen evolution polarization data combined with voltammetric deconvolution data provide information about the nickel electrodissolution inhibition capability of these substances in acid solution.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada