Efficient surface enhanced Raman scattering from Cu2O porous nanowires transformed from CuO nanowires by plasma treatments

Abstract

Porous Cu2O and Cu2O/CuO nanowires composed of nanoparticles were prepared for the first time by reactions of CuO nanowires with H2 or H2/N2 mixed plasma at room temperature. The roughness and Cu2O/CuO ratio of the porous nanowires could be adjusted by controlling the flow rate ratio and power of plasma treatments. Scanning electron microscopy and high-resolution transmission electron microscopy show that the average size of the particles on the porous nanowires increases from around 5 to 10 nm as the flow rate ratio of N2 to H2 increases from 0 to 4. In addition, reduction of CuO to Cu2O increases with the flow rate ratio of H2 to N2. Surface enhanced Raman scattering (SERS) measurements of 4-aminobenzenethiol on the porous nanowires shows strong signals, which increase with the decrease of CuO/Cu2O ratio and particle size of the porous nanowires. The extraordinary enhancement of such SERS signals is attributed to numerous nanoparticles acting as hot spots on the surface of the porous nanowires. The work not only reports on the synthesis of novel porous Cu2O nanowires comprised of nanoparticles, but also demonstrates efficient SERS activity, which sheds light on possible chemical sensing applications of semiconductor nanomaterials.