Figure 3

The room-temperature PL spectra of ZnO nanowires.a Grown in air atmosphere;b grown in the mixed gas stream. The samples were dispersed in DMF, sonicated for 1 h, and the sediment-1 was collected after 8 h subsidence. The remaining dispersion system was resonicated for 1 h, subsided for 30 h, and then the sediment-2 was separated. This procedure was repeated, the sediment-3 was obtained after 60 h subsidence. The last remaining dispersion was named as residual dispersion. These sediments were dispersed in DMF again, sonicated for 15 min, and the PL measurement was performed at room temperature