Layer-by-layer grown electrodes composed of cationic Fe3O4 nanoparticles and graphene oxide nanosheets for electrochemical energy storage devices

Ultrathin electrodes composed of layer-by-layer as-sembled (3-aminopropyl)trimethoxysilane functionalized iron oxidenanoparticles and graphene oxide nanosheets were prepared by a simpleand low-cost dip coating method without using any binders orconductive additives. The thickness of the Fe3O4/GOfilms was simplyaltered with the number of dip coating cycles. Multilayeredfilms werechemically reduced with hydrazine vapor in order to increase theelectrical conductivity. Characterization of multilayerfilms wasperformed with scanning transmission electron microscopy, UV−visspectroscopy, atomic force microscopy, quartz crystal microbalance, X-ray photoelectron spectroscopy, and electron paramagnetic reso-nance spectroscopy. We have performed cyclic voltammetry and electrochemical impedance spectroscopy for the evaluationof Fe3O4/GO multilayers as possible electrochemical capacitor electrodes. Reduced Fe3O4/GOfilms exhibit high specificcapacitances (varying between 200 and 350 F g−1at 5 mV s−1), outperforming the layer-by-layer assembled iron oxides/carbonderivatives (carbon nanotube, graphene)