Graphene/copper oxide nanoparticles thin films as precursor for graphene/copper hexacyanoferrate nanocomposites

This paper reports a simple, direct and in situ route to prepare different graphene/copper oxide nanoparticles thin films, followed by the demonstration of their use as precursors for graphene/copper hexacyanoferrate. Starting from an aqueous dispersion of graphene oxide and aqueous solution of copper nitrate, films of graphene/Cu2O/CuO were obtained after a reaction with sodium borohydride at a water/toluene liquid/liquid interface. Different films were prepared varying the Cu2+/GO/BH4- ratio, deposited over suitable substrates and characterized by UV-Vis and Raman spectroscopy, X-ray diffraction, thermal analysis, and scanning electron microscopy. The films presented high transparence (94% of transmittance) and homogeneity, and they were constituted by nanoparticles of Cu2O and/or CuO, with different sizes and shapes (spheres, cubes, ellipses), homogeneously dispersed over graphene sheets. The films were further deposited over glass/ITO substrates and used as working electrodes in an electrochemical cell containing a KCl/[K3Fe(CN)(6)] aqueous solution as electrolyte, aiming the use of the copper oxide nanoparticles as precursors for the electrochemical synthesis of the Prussian blue analogue copper hexacyanoferrate. Several experimental variables were studied to find the optimal conditions for the preparation of graphene/Prussian blue analog nanocomposites, which were obtained through an original experimental procedure, as demonstrated by different characterization techniques.