Ultraviolet light–assisted synthesis of nanostructured carbon materials for supercapacitor electrodes by using zinc oxide structures as template and catalyst

Abstract

Different kinds of highly porous nanostructured carbon (xerogels) were obtained by a new synthetic strategy based on surface-driven polymerization of resorcinol–formaldehyde resin in the presence of zinc oxide (ZnO) nanostructures. The synthesis method involved spatially confined polycondensation of resorcinol with formaldehyde in the presence of ZnO nanostructures, which act as a scaffold as well as a catalyst assisted by ultraviolet (UV) light irradiation. Using this method, two different carbon-based nanomaterials composed of ZnO nanostructures coated with carbon were prepared. The regulation of synthesis parameters, including monomer concentration and UV exposition time, leads to the synthesis of different porous materials, as was evidenced by scanning electron microscopy and transmission electron microscopy images. Electrochemical characterization of the prepared materials showed specific capacities up to 140 F g−1, as well as high charge/discharge rate. Once an electrode is integrated in an experimental capacitor, the material exhibits an electrochemical operative window up to 1.8 V in aqueous media, with a specific energy density of 23 Wh/kg and a power density of 7.3 × 103 W/kg of active material. Graphical Abstract: Schematic representation of light-assisted synthesis of carbon nanomaterials using ZnO structures as catalysts/template, showing the principal stages of the process.