Facile synthesis of ZnO-Au nanocomposites for high-performance supercapacitors

A facile and economic method for the synthesis of ZnO-Au heterostructured nanoflowers was developed by implementing a surfactant-mediated route. Pure ZnO nano-flowers were initially synthesized and Au nanoparticles (NPs) were further deposited on the ZnO surface by using hydrazine hydrate as a reducing agent. The effect of the accumulated Au NPs on the surface of ZnO was demonstrated by applying the as-synthesized nanostructures in supercapacitors. The ZnO-Au composite functioned as a pseudocapacitor electrode in 2 M KOH aqueous electrolyte. The Au NP formed a systematic nanocomposite after deposition on the ZnO surface. The composite exhibited enhanced conductivity and hence high specific capacitance and good cycling stability during cyclic voltammetric and charge/discharge analyses when used as the electrode material in supercapacitors. The average specific capacitance of the fabricated composite was augmented relative increasing from 89 Fg-1 (ZnO nanoflowers) to 205 Fg-1 (ZnO-Au composite) at a scan rate of 20 mVs-1 in a two-electrode system at 0 to 0.8 Ag-1 current density. Metal oxides are considered the most promising materials for next-generation supercapacitors owing to their unique physical and chemical properties. The magnificent performance of the composite material is attributed to the synergetic effects of the size and good redox activity of the ZnO particles, combined with the high surface area of the ZnO-Au composites.