The main research field of the independent research group "Nanoanalytics and Interfaces" is the in-depth characterization of materials for renewable energy application and hydrogen economy. State-of-the-art aberration corrected scanning transmission electron microscopy (STEM) and its analytical methods such as electron energy loss spectroscopy (EELS) are applied to obtain information on the atomic arrangement and chemical composition of the materials down to the atomic scale. A strong focus is laid on crystal defects such as interfaces or grain boundaries and on the effect of nanostructuring. The results are correlated to the synthesis conditions and used to determine structure-properties relationships. In addition, strategies are developed to improve functional properties and increase the stability of the materials of interest. The investigated material systems find applications in photocatalysis, fuel cells, electrochemistry, light emitting or thermoelectric devices. In addition, thin films used for metal contacts and as protective layers are studied.