Formation of ZnO rods with varying diameters from ε-Zn(OH)2

• ZnO rods with varying diameters were synthesized from ε-Zn(OH)2 precursor.
• The influence of temperature on the formation of ZnO from ε-Zn(OH)2 was investigated.
• Formation mechanism of ZnO rods from ε-Zn(OH)2 was discussed.
• A facile two-stage route was developed to synthesize ZnO nanorods with thin diameters and high photo-degradation activity.

The influence of temperature on the formation of one-dimensional (1D) ZnO from ε-Zn(OH)2 via solution route was studied in this paper, using ZnSO4 and NaOH as the raw materials. The experimental results indicated that the increase of temperature from 25 °C to 80 °C accelerated the conversion of ε-Zn(OH)2 to ZnO, leading to the formation of 1D ZnO with comparative big diameters. A two-stage route was then developed to synthesize ZnO nanorods with diameters of 20–100 nm and lengths of 1–3 μm by aging Zn(OH)2 in 1.0 mol L−1 NaOH at 25 °C for 72 h followed by aging the slurry at 80 °C for 2 h. Compared with the ZnO submicron-rods (diameters: 100–500 nm, lengths: 1–3 μm) formed at 80 °C, the ZnO nanorods formed via the two-stage route exhibited a thinner diameter and a higher photo-degradation activity for Rhodamine B owing to the pre-formation of ZnO nanorods (diameters: 10–50 nm) on ε-Zn(OH)2 surface at 25 °C as well as the existence of more oxygen defects.