Morphology control of Cu(OH)2 nanowire bundles via a simple template-free route

► Cu(OH)2 nanowire bundles were prepared by a H2O2-assisted wet chemical route. ► Higher H2O2 concentrations resulted in longer Cu(OH)2 bundles. ► Role of H2O2 is to promote Cu(OH)2 recrystallization and directional growth.