Preparation of nitrogen-doped titania with high visible light induced photocatalytic activity by mechanochemical reaction of titania and hexamethylenetetramine - Komatsu, Masakazu.; Saito, Fumio.; Sato, Tsugio.; Tang, Qing.; Wang, Jinshu.; Yamaki, Hiroshi.; Yin, Shu.; Zhang, Qiwu.