Laser Reduction of Graphene Oxide/Zinc Oxide Nanoparticle Nanocomposites as a One‐Step Process for Supercapacitor Fabrication

Herein, the laser reduction of graphene oxide (GO) and zinc oxide nanoparticle (ZnONP) nanocomposite films is proposed as a one‐step process for supercapacitor fabrication. The films, deposited by casting onto a flexible poly(ethylene terephthalate) (PET) substrate coated with indium‐doped tin oxide (ITO), are subjected to laser irradiation (5 mW, 405 nm) to reduce the GO phase and produce laser‐reduced GO (LRGO). Scanning electron microscopy/energy dispersion spectroscopy (SEM–EDS), micro‐Raman spectroscopy, and current versus voltage (I × V) analyses show a partial reduction of GO to LRGO, forming several conductor‐insulating (LRGO/GO) microporous interfaces, and thereby favoring the formation of a supercapacitor structure. Moreover, the topmost LRGO film layer is extensively reduced, making it sufficiently conducting to work as the counter electrode as well. However, the reduction process is less effective when ZnONPs are introduced into the GO matrix because ZnONPs get clustered and scatter the incident laser before reaching the GO phase. The capacitive behavior, assessed by cyclic voltammetry and galvanostatic charge–discharge measurements, reveals the following specific capacitances: 2.68 F g⁻¹ (GO/LRGO) and 1.44 F g⁻¹ (GO/LRGO/ZnONP). The method proposed herein is advantageous because it produces the microcapacitor structures and LRGO counter electrode in a single laser reduction step.