In-situ Quantification of Nanoparticles Oxidation: A Fixed Energy X-ray Absorption Approach

The oxidation of palladium nanoparticles causes the performance degradation of alkaline direct ethanol fuel cells. Quantifying this oxidation is a task of tremendous importance to design mitigation strategies that extend the service life of catalysts and devices. Here, we show that the Fixed Energy X-ray Absorption Voltammetry (FEXRAV) can provide this information with an in-situ approach. To do so, we have developed a quantification method that assumes the linear response at fixed energy. With this method, we have investigated the oxidation of carbon black-supported palladium electrocatalysts during cyclic voltammetry in the same solution employed as a fuel in the direct ethanol fuel cells. We have shown that up to 38% of the palladium is oxidised at 1.2 V vs. RHE and that such oxidation also happens at lower potentials that the catalyst can experience in real direct ethanol fuel cells. The result of this study is a proof of concept of quantitative FEXRAV.