Effect of Mass Transport on the Electrochemical Oxidation of Alcohols Over Electrodeposited Film and Carbon-Supported Pt Electrodes

Abstract

Electrochemical oxidation of four different alcohol molecules (methanol, ethanol, n-butanol and 2-butanol) at electrodeposited Pt film and carbon-supported Pt catalyst film electrodes, as well as the effect of mass transport on the oxidation reaction, has been studied systematically using the rotating disk electrode (RDE) technique. It was shown that oxidation current decreased with an increase in the rotation rate (ω) for all alcohols studied over electrodeposited Pt film electrodes. In contrast, the oxidation current was found to increase with an increase in the ω for Pt/C in ethanol and n-butanol-containing solutions. The decrease was found to be nearly reversible for ethanol and n-butanol at the electrodeposited Pt film electrode ruling out the possibility of intermediate CO ads poisoning being the sole cause of the decrease and was attributed to the formation of soluble intermediate species which diffuse away from the electrode at higher ω. In contrast, an increase in the current with an increase in ω for the carbon supported catalyst may suggest that the increase in residence time of the soluble species within the catalyst layer, results in further oxidation of these species. Furthermore, the reversibility of the peak current on decreasing the ω could indicate that the surface state has not significantly changed due to the sluggish reaction kinetics of ethanol and n-butanol.

Pt/C and Pt/SnOx/C Catalysts for Ethanol Electrooxidation: Rotating Disk Electrode Study

“…However, in real electrochemical applications (fuel cells or electrochemical convertors), the alcohol is supplied to the anode electrode, that is, the system is under hydrodynamic conditions. It is thus important to take into account the effect of fuel transport to the catalyst [21] and the transfer of byproducts through the catalyst layer.…”

A Hybrid Catalyst-Bonded Membrane Device for Electrochemical Carbon Monoxide Reduction at Different Relative Humidities

“…Ethanol has been electrochemically oxidized in basic media to several products including acetate, acetylaldehyde, and CO2. [28][29][30] To determine the extent to which ethanol could be oxidized to any of these products, a control experiment was performed by spiking the anolyte with 1000 ppm ethanol with bulk electrolysis performed under N2 flow. Figure 4a shows a schematic illustration of the vapor-fed testbed in Multi-physics modeling, with the calculation domain of the 2D model for water-vapor transport available in the Supporting Information file.…”

Formic Acid and Methanol Oxidation for Pt/C Catalyst Depending on Rotating Speed, Scan Rate and Concentration

“…Similar results to formic acid oxidation were seen that the peak currents of methanol oxidation decreased with the increase in the rotating speed. The decrease indicates that the reaction is not mass transport controlled and suggests increased diffusion of reactive species away from the electrode surface with the increase of the rotating speed [14]. Seland et al showed that the current density of methanol oxidation is decreasing as a function of rotating rate both in the positive-going scan and the negative-going scan [15].…”