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In this article an overview of our research in the field of nanoelectrocatalysis, in particular electrocatalytic energy conversion, is presented. Our research comprises the areas of catalyst preparation as well as performance evaluation of model and applied electrocatalysts with respect to activity, selectivity, and stability. Our aim is to understand the fundamental properties that determine the performance of electrocatalysts for particular processes and to build a bridge between fundamental research and realistic applications. In our research we prepare catalyst materials, study the interface between the catalyst and the electrochemical environment, i.e. the solid–liquid interface, and perform kinetic measurements. Furthermore, such research relies to a large extent on material characterization techniques as well as the development and application of advanced experimental setups.

The electrochemical scanning tunneling microscope was the first tool for the investigation of solid–liquid interfaces that allowed in situ real space imaging of electrode surfaces at the atomic level. Therefore it quickly became an important addition to the repertoire of methods for the determination of the local surface structure as well as the dynamics of reactions and processes taking place at surfaces in an electrolytic environment. In this short overview we present several examples to illustrate the powerful capabilities of the EC-STM, including the observation of clean metal surfaces as well as the adsorption of thin metal layers, specifically adsorbed anions and non-specifically adsorbed organic cations. In several cases the electrode potential has a significant influence on structure and reactivity of the surface that can be explained by the observations made with the EC-STM.

At the synchrotron BESSY we run the experimental station SoLiAS, dedicated to solid–liquid interface analysis with soft X-ray induced photoelectron spectroscopy (SXPS). SoLiAS allows wet chemically prepared surfaces to be transferred to the ultra high vacuum without contact with ambient air. In addition in situ (co)adsorption of volatile solvent species onto liquid nitrogen cooled samples is possible. SoLiAS proves to be very useful in analyzing the chemical and electronic structure at the solid–liquid interface of dye–sensitized solar cells. The standard dye RuII(2,2?-bipyridil-4,4?-dicarboxylate)2(NCS)2 was adsorbed from ethanol solution under clean N2 atmosphere in an UHV-integrated electrochemical cell (EC). The standard solvent acetonitrile was adsorbed in situ from the gas phase. For comparison also the nonpolar solvent benzene was adsorbed. Ex situ sintered nanocrystalline anatase substrates as well as in situ deposited polycrystalline TiO2 samples were used, which show a similar distribution of two types of occupied surface states. Distinct reversible changes occur in synchrotron-induced photoelectron valence band and core level spectra when the solvent acetonitrile is adsorbed to pristine and dye-covered TiO2 substrates. TiO2 surface states are quenched and the line width of the dye S2p emission decreases strongly. Based on the experimental results the alignment of the photovoltaic relevant electronic states and a model on the dye–solvent interaction can be deduced that points to the promotion of vectorial charge transfer by increased dye orientation due to solvation.