Firstly, stacks of GO sheets were fabricated via vacuum filtration of GO solution through microporous silver membranes. Subsequently, the resulting GO films were electrochemically reduced and Cr2O3 was directly created within the rGO stack. The electrochemical process was performed in a custom-made electrochemical cell (Figure ). As a working electrode, the GO film on the porous silver substrate was screwed against a conductive sample holder. A platinum (Pt) electrode was used as counter electrode, an Ag/AgCl electrode as reference electrode. CrCl3•6H20 (0.1 M) in aqueous solution was used as electrolyte. The experimental setup and procedures are described in more detail in the materials and method section.