Multigram synthesis of copper nanowires using ac electrodeposition into porous aluminium oxide templates

Abstract

Multigram quantities of Cu nanowires ca. 25 nm in diameter and µm in length have been produced by AC electrodeposition into porous aluminium oxide (PAO) templates. Multiple, large-area Al electrodes (5 × 11 cm or 10 × 25 cm) are anodized in parallel at 25.0 V in 0.3 M H₂SO₄(aq) using custom built baths. The pores are efficiently filled by applying 200 Hz sine waves at 10 V_rms between the anodized Al and Cu plate counter electrodes immersed in a 0.50 M CuSO₄(aq) solution. Dissolution of the PAO template in 0.6 M H₃PO₄ to free the Cu nanowires results in significant coarsening of the nanowires, whereas dissolution of the PAO template in 1.0 M NaOH(aq) results in retention of the Cu nanowire diameters corresponding to the pore diameter of the PAO template. Liberated Cu nanowires were characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy.