Determination of the flat band potential of doped and non-doped nanoparticles in aqueous environment using a novel electrode preparation method

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For many applications and especially for an evaluation of the toxicity, the electrochemical properties of nanoparticles are essential. These are related to the flat band potential, i.e. the electrochemical potential, of the nanoparticles, which depends on the synthesis method and may be modified through doping of foreign atoms into the nanoparticles. The electrochemical potential also has an influence on the zeta-potential that determines the agglomeration behavior of particles in suspensions and the surface reactions proceeding in aqueous biological environments. The knowledge of the exact flat band potential of nanoparticles would greatly enhance our understanding of particle surface charges. However, the electrochemical characterization of nanoparticles via impedance spectroscopy using porous electrodes, which preserve the nanoparticles surface properties, is limited due to the disturbing contributions of the substrate-electrolyte contact. The aim of our proposal is to develop and fundamentally understand a novel electrode preparation method, which allows to block the disturbing contribution of the substrate-electrolyte contact of the porous electrodes and enables a fast particle characterization in aqueous environments. With the sucessful implementation of our electrode preparation method we are able to determine the flat band potential of nanoparticles and assess to which extend doping allows for a modification of the electrochemical properties, i.e. the flat band potential and the zeta-potential, of the nanoparticles.