Variation of crystallinity of Cu and Cu2O nanowires arrays grown in various pores of porous alumina membrane

Yu-Min Shen¹, Wen-Fang Chiu¹, Sheng-Chang Wang², Pramoda K. Nayak¹, Dipti. R. Sahu^{1, 3*}and Jow-Lay Huang^{1, 4, 5*}

¹Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan, Republic of China

²Department of Mechanical Engineering, Southern Taiwan University of Science and Technology, Tainan 710, Taiwan, Republic of China

³Department of Natural and Applied Sciences, Namibia University of Science and Technology, Private Bag 13388, Windhoek, Namibia

⁴Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan, Republic of China

⁵Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan, Republic of China

Adv. Mater. Lett., 2017, 8 (11), pp 1046-1051

DOI: 10.5185/amlett.2017.1493

Publication Date (Web): Aug 05, 2017

E-mail: dsahu@nust.na, jlh888@mail.ncku.edu.tw

Full Article

Abstract

Various pore sizes of a porous alumina membrane were fabricated using H₂SO₄ and H₂C₂O₄ electrolyte under different ionization voltages. Cu nanowire arrays with high aspect ratios, uniform pore size, and ordered pore arrangement were synthesized using the above porous alumina membrane (PAM). Moreover, Cu₂O nanowire arrays were prepared through the oxidization of Cu metal nanowire arrays. From the microstructure and compositional analysis, it was observed that pores of different sizes, i.e. 20~30, 70~90 and 90~100 nm could be obtained by controlling various electrolytes and anodization voltage. The Cu nanowire synthesized with various pore sizes were found to be single crystal (20~90 nm) and polycrystalline (90~100nm) respectively. The single crystal Cu with (111) direction was occurred due to homogeneous current density distribution and relationship between current density (J) and nucleus radius (r_o). After oxidation of Cu, the Cu₂O nanowires with the pore sizes of 20~100 nm was found to be single crystal. The rearranged of Cu and O₂ lattice sites promotes the enhancement of crystalline property.