Reduced graphene oxide/iron oxide nanohybrid flexible electrodes grown by laser-based technique for energy storage applications

Porous reduced graphene oxide (rGO)/iron oxide nanohybrid thin films were grown through a laser-based technique onto flexible polymer, polydimethylsiloxane substrates. A frequency quadrupled pulsed Nd:YAG laser source (lambda = 266 nm, tau(FWHM) similar to 4 ns, upsilon = 10 Hz) was used for irradiation of dispersions containing the starting nano-materials, graphene oxide (GO) platelets and iron oxide nanoparticles (NPs), to be transferred to the substrates surface. The electrochemical response of the composite layers was investigated by cyclic voltammetry in dark and under UV/visible light illumination, as well as by electrochemical impedance spectroscopy. A comparative study was performed as a function of the nature of the GO base materials, monolayer or multilayer GO platelets, and relative concentration of GO/iron oxide NPs in the dispersions submitted to laser irradiation. The capacitance values of the nanohybrid materials which contain monolayer GO were found to be one order of magnitude higher as compared to their counterparts consisting of multilayer GO and iron oxide NPs. UV-visible light irradiation contributed to the significant enhancement of the electrochemical properties of the electrodes. These results indicate that the nanohybrid thin films are promising candidates as flexible electrodes in micro-supercapacitors and photoelectrochemical devices for simultaneous energy storage and solar energy conversion.