Copper oxide nanosheets and nanowires grown by one-step linear sweep voltammetry for supercapacitor application

Copper oxides nanosheets and nanowires were directly grown on a copper sheet by a single step voltammetry process in an alkaline solution. The transition from the out-of-plane nanosheets to high aspect ratio nanowires is triggered by the change in the voltage sweep rate. The scan rate changes the growth mechanism from nucleation and coarsening at the slow scan rate for nanosheets to an oriented oxide nanowire growth at high scan rates. Polycrystalline copper oxide nanostructures contain both Cu(I) and Cu(II) oxide phases, which were char-acterized by the FEG-SEM, XRD, XPS, Raman, and TEM analysis. The copper oxides nanosheets and nanowires electrodes delivered the maximum specific areal capacitance 320 mF cm(-2), energy density 3.36 mu Wh cm(-2) and, power density 1.7 mW cm(-2) with capacitance retention of 115% up to 5000 cycles. The process presents a simple, low cost and scalable option for the preparation of binder-free copper oxides nanowires and nanosheets electrodes for supercapacitor application.