The lack of stable and economic supporting materials at high voltages hampers the development of electrocatalysts for oxygen evolution reaction (OER), which is the major source of energy loss in water splitting to produce hydrogen. In this work, we developed systematic methods to evaluate candidate compounds that can potentially replace traditional carbon support for OER catalysts. Stability, economic and conductivity criteria of the oxide support materials were studied and discussed. A nano-sized antimony-doped tin oxide was fabricated to support RuO 2 , which was shown to provide the highest stability and activity of OER in 0.5 M H 2 SO 4 up to 2.5 V RHE and up to 55 • C.

The electro-oxidation reactions of methanol and ethanol were studied in sulfuric acid and potassium hydroxide solution. Different electrode materials were tested for this reaction including base metal electrodes in the alkaline case. Tests were performed using standard electrochemical techniques such as cyclic voltammetry, chronoamperometry and differential electrochemical mass spectrometry. Comparing both reactions it was found that in the acidic environment the methanol oxidation proceeds faster and is more complete than the ethanol oxidation. However, the situation changes in alkaline solution. Here, the kinetic enhancement of the ethanol oxidation reaction is in many cases so strong that the ethanol oxidation kinetics become faster than the methanol oxidation kinetics at the same metal and under the same conditions.

a b s t r a c tNanostructured palladium-copper electrocatalysts with Pd:Cu ratios of 1:3, 1:1, and 3:1 were synthesized using a Sacrificial Support Method (SSM) in combination with the thermal reduction of metal precursors. The materials were comprehensively characterized by X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning and Transmission Electron Microscopy (SEM and TEM), surface area measurements (Brunauer-Emmett-Teller, BET) and Differential Electrochemical Mass Spectroscopy (DEMS). The SSM method enables the preparation of nano-sized unsupported Pd-Cu catalysts with uniformlydistributed particles and high surface area, in the range of 40 m 2 g catalyst −1 . Their catalytic activity for the electrooxidation of several alcohols (methanol, ethanol, ethylene glycol and glycerol) was investigated in alkaline media. In situ Infrared Reflection Adsorption Spectroscopy (IRRAS) and Density Functional Theory (DFT) calculations were used in order to understand the mechanism of the various alcohols electrooxidation reactions.

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In this study, the adsorption of ethanol on platinum in alkaline medium is investigated by stripping voltammetry in combination with differential electrochemical mass spectrometry (DEMS). It is shown that the amount of adsorbed ethanol depends on the adsorption potential. Adsorbed ethanol can be oxidized to carbon dioxide in two different potential regions: one below 0.9 V vs. RHE and the other above 0.9 V vs. RHE. Furthermore, adsorbed ethanol can be reduced to methane below 0.2 V vs. RHE when the stripping voltammogram is started in cathodic direction from the adsorption potential. The number of electrons transferred per molecule of carbon dioxide evolved is calculated and found to be two in the potential region below 0.9 V vs. RHE, independent of the adsorption potential. A larger number of electrons is found in the potential region above 0.9 V vs. RHE. Based on the findings, a preliminary reaction scheme is presented.

In this contribution, the electro-oxidation of ethanol in alkaline medium is studied with differential electrochemical mass spectrometry (DEMS). Starting from platinum as model catalyst, the influence of the catalyst on the ethanol oxidation reaction is investigated with other metals, i.e. palladium, gold and nickel. It was found that the reaction products and their current efficiencies depend strongly on the catalyst used. At platinum the reaction to acetate is the major current producing path while the current efficiency for carbon dioxide is low. At higher ethanol concentrations ethyl acetate is formed. During the ethanol oxidation at palladium the current efficiency for acetate is even higher and only traces of carbon dioxide are formed. However, an ethyl acetate formation was not observed. Gold shows a significant activity for the ethanol oxidation with ethyl acetate being the only detected product. The activity of nickel towards the ethanol oxidation in alkaline medium is negligible.

An ethanol derivative and fusel oil were investigated regarding their possible use as denaturing agents for ethanol for DEFC in 0.5 M sulphuric acid and 0.1 M potassium hydroxide solution at platinum by means of cyclic voltammetry and differential electrochemical mass spectroscopy. It was found that fusel oil is not suitable as denaturing agent for DEFC due to strong adsorption to platinum surfaces and the hindrance of the ethanol conversion. On the other hand, the investigated ethanol derivative does not hinder the ethanol conversion as much and therefore seems to be a promising candidate for a denaturing agent to use with ethanol in DEFC.