XPS and ToF-SIMS depth profiling as well as EDX and Raman spectroscopy, confirm well distributed presence of Cr2O3 within the depth (500 nm) and in lateral direction (2.5 cm 2 ) of the rGO films. The analysis of XRD and SEM cross-sections of the sandwich structures confirm that Cr2O3 grows inside the laminated structure of rGO with a maximum thickness of ~4.3 Å. In TEM we could observe that Cr2O3 polycrystals grow with dominant surface of (11 � 0), which is aligned with the basal plane of rGO. Moreover, during our extensive XPS, XAS, FTIR analysis, Cr-C or Cr-O-C bonds were not detectable.