Table 1: Effect of annealing temperature on ZnO surface area and pore size.

ZnO sampleSurface area, m2/gAverage pore size, nm

As-prepared nanotube (hydrothermal technique)17.8278.6
500°C annealing16.7255.4
700°C annealing7.2114.6
900°C annealing2.453