Rayleigh Instability Driven Nodular Cu2O Nanowires via Carbothermal Reduction of CuO Nanowires

Nodular cuprous oxide (Cu2O) vertical nanowire (NW) arrays with a length of more than 20 μm and diameter of ∼300 nm have been synthesized by the carbothermal reduction of thermally grown cupric oxide (CuO) NWs. The transformation initiates at a low temperature of 350 °C. Two important effects are observed: First, the CuO → Cu2O reduction occurs by oxygen out diffusion under a highly reducing atmosphere afforded by the presence of carbon monoxide (CO). Second, the surface reduction creates instabilities, which propagate and grow into a string of nodules along the length of the Cu2O NWs. This effect is determined to be due to Rayleigh instability, but initiated via Cu2O phase transformation.