EFTEM and EELS analysis of a Pt/NiO interface

Energy-filtering transmission electron microscopy (EFTEM) is more and more becoming an important nanoanalytical technique in both materials science an d biology, The main advantage of the method lies in the possibility to obta in two-dimensional chemical information from large specimen areas as well a s from features on a nanometer scale. Due to its excellent lateral resoluti on it is perfectly suited for the investigation of nanometer sized features (e.g, interfaces). In this paper we will show how EFTEM can be used to characterize the interf ace between a Pt layer and a NiO crystal as part of a coulometric titration cell. In addition to elemental distribution maps electron energy-loss spec tra (EELS) across the interface (EELS linescans) have been acquired to obta in quantitative compositional profiles. By employing these methods the foll owing interfacial layers could be identified, all of which containing Pt, N i and O in different proportions: 13 nm Pt-rich, 32 nm Ni-rich and 29 nm Pt -rich. The origin of these is discussed in terms of displacement reactions.