Combinational reduction of graphene oxide via coherent and incoherent light irradiation for flexible supercapacitors

Abstract The effect of combinational reduction by coherent and incoherent light sources of graphene oxide (GO) in fabricated thin flexible film supercapacitors was studied. Coherent light irradiation produces equally divided cracks on a reduced GO (rGO) surface, followed sequentially by incoherent light irradiation from a xenon camera flashtube source that not only significantly increases the overall degree of cracking on the surface substantially but also swells the rGO sheet vertically. Combinational light irradiation composed of sequential coherent and incoherent light sources efficiently reduces GO and increases the surface area of rGO, which was investigated through Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The enlarged surface area of the cracked rGO flakes can improve the specific energy and power of the supercapacitor, which were evaluated using cyclic voltammetry and galvanostatic charging/discharging measurements. The specific energy and power of the combinational light irradiation rGO supercapacitor were approximately 1000% and 100% higher than those of solitary coherent and incoherent light irradiation rGO supercapacitors, respectively.