General in situ chemical etching synthesis of ZnO nanotips array

In this letter, we present a general solution based in situ chemical etching strategy to synthesize ZnO nanotips arrays. The in situ chemical etching can generate nanotips with controllable tip morphologies on various substrates, and the nanotips density is tunable via etching ZnO nanorods with different root diameters. The preferential etching along $c$ axis and the curvature dependence of the $\mathrm{N}{\mathrm{H}}_3$ molecule absorption on the nanorod tip are considered responsible for the formation of ZnO nanotips. This general in situ chemical etching method will significantly advance the research in the ZnO nanotips based nanodevice.