Search

The oxygen reduction reaction (ORR) mechanism for electrochemical production of hydrogen peroxide is investigated for an Au-Pd catalyst with 25 at% palladium. The sample was prepared by chemical reduction of a precursor solution on a carbon-based substrate. Rotating ring-disk electrode (RRDE) measurements were performed for electrochemical characterization exhibiting H2O2 current efficiencies of about 75-78% at low disk potentials. The focus of this article is on the mathematical evaluation of the experimental data using the analytical method from Damjanovic et al. [J. Chem. Phys. 45, 4057 (1966)] and a powerful numerical data fitting technique based on RRDE simulations in MATLAB, which is capable of investigating reaction mechanisms with different structures. The latter method is presented in detail and the electro-kinetic parameters of the ORR mechanism at the considered catalyst resulting from both methods are compared quantitatively. It is found that the oxygen reductions via the 2-electron and the 4-electron pathways occur in parallel, whereas the hydrogen peroxide reduction pathway is found apparently inactive. [ABSTRACT FROM AUTHOR]

Acidic or alkaline direct ethanol fuel cells (DEFCs) can be a sustainable alternative for power generation if they are fuelled with bioethanol. However, in order to keep the fuel cheap, ethanol has to be exempted fromtax on spirits by denaturing. In this investigation the potential denaturing agents fusel oil, tert-butyl ethyl ether, and Bitrex were tested with regard to their compatibility with fuel cells. Experiments were carried out both in sulphuric acid and potassium hydroxide solution. Beside, basic electrochemical tests, differential electrochemicalmass spectrometry (DEMS) and fuel cell tests were conducted. It was found that fusel oil is not suitable as denaturing agent for DEFC. However, tert-butyl ethyl ether does not seem to hinder the ethanol conversion as much. Finally, a mixture of tert-butyl ethyl ether and Bitrex can be proposed as promising candidate as denaturing agent for use in acidic and alkaline DEFC. [ABSTRACT FROM AUTHOR]