Pom-pom-like nanowire clusters prepared by potentiostatic oxidation of copper in NH4HCO3 solution

Abstract

Formation of hemispherical pom-pom-like clusters of nanowires during potentiostatic oxidation of copper in NH 4 HCO 3 is reported. High-purity copper was oxidized in a three-electrode setup at constant electrode potential ranging from 200 mV to 1000 mV vs. Ag|AgCl|sat. KCl for 14 h. The obtained clusters of nanwires were examined using FE-SEM, XRD and XPS techniques. The diameter of nanowires, composed mainly of CuO, Cu 2 O, Cu(OH) 2 , and Cu 4 O 3 , was ca. 50–70 nm. The diameter of the clusters strongly depends both on the applied potential and the time of electrooxidation, and was found to be in the range of 1–3 μm. The mechanism for the formation of such nanowires clusters is proposed. • Clusters of nanowires form on copper during potentiostatic oxidation in NH 4 HCO 3 . • The outer layer of nanowires is composed of mostly Cu(OH) 2 and CuO. • Cu 2 O, CuO, Cu(OH) 2 , Cu 4 O 3 and Cu 2 CO 3 (OH) 2 are present in internal layer. • The cluster diameter depends on the applied potential and time of oxidation.