Double-nucleation hydrothermal growth of dense and large-scale ZnO nanorod arrays with high aspect ratio on zinc substrate for stable photocatalytic property

We have successfully fabricated dense and large-scale ZnO nanorod (NR) arrays by hydrothermal growth in Zn-NH3·H2O system by the addition of zinc nitrate. The characterizations demonstrate that the as-prepared sample has a large dimension of ZnO NR arrays with a density of ∼105/μm2 and an aspect ratio of ∼100. It is supposed that the high density is attributed to the double-nucleation phenomenon related to the zinc salt solution and oxidation of substrate, and the high aspect ratio relies on sufficient zinc source for c-axis growth. A possible growth mechanism was proposed. The photocatalytic studies of the ZnO NR arrays displayed high photocatalytic efficiency and stability. This facile strategy for the preparation of discretionary dimensions of ZnO NR arrays can be applicable to the photocatalytic field for manifold cycles.