Laser fabrication of hybrid electrodes composed of nanocarbons mixed with cerium and manganese oxides for supercapacitive energy storage

Novel composite materials are being investigated for improving the energy storage performance of electrochemical capacitors. For this goal, synergistic effects via the combination of diverse types of materials are crucial. In this work, electrodes composed of reduced graphene oxide, multiwall carbon nanotubes, as well as cerium and manganese oxides were fabricated through reactive inverse matrix-assisted pulsed laser evaporation (RIMAPLE). UV-pulsed laser irradiation of frozen aqueous dispersions containing graphene oxide sheets, carbon nanotubes, and ceria nanoentities, besides manganese acetate precursor, led to the simultaneous chemical transformation and co-deposition of hybrid electrodes onto flexible metallic substrates via photothermal and photochemical processes. Thorough morphological and compositional studies of the electrodes demonstrated the laser-induced reduction of graphene oxide, besides the crystallization of a mixture of cerium and manganese oxide nanostructures decorating the carbon nanoentities during the deposition process. Electrochemical analyses revealed a remarkable improvement of performance with the combination of electrochemical double layer in the porous nanocarbon framework with pseudocapacitance from the oxide nanostructures, obtaining excellent volumetric capacitances of up to 140 F cm-3 at 10 mV s-1 with the combination of all four materials. The attained results are the best ones yet published regarding RIMAPLE of hybrid nanocarbon-based electrodes with micrometric thickness. Finally, symmetric electrochemical capacitors were fabricated using aqueous electrolyte, revealing excellent stability upon tens of thousands of charge-discharge cycles.