The morphology of as-synthesized and nitrogen-doped TiO2 sample are shown in Fig. 5. It was found
that the as-synthesized TiO2 (Fig. 5 (a)) shown in the shape of nanorods about 10-100 nm in diameter and
several hundred nanometers in length. For the nitrogen-doped TiO2 which used 0.5M of guanidine
carbonate and followed by heat treatment at 400