Controllable preparation of black titanium dioxide and its wave-absorbing properties

The black TiO2 material was prepared by chemical reduction method, and the difference in structure and performance between black TiO2 and white TiO2 was discussed. At the same time, the effects of hydrogenation temperature and mass ratio factors on the formation and structure of black TiO2 were investigated. The results show that black TiO2 has a special structure: the existence of oxygen vacancies shortens the Ti–O bond, and the lattice shrinks. In addition, defects such as Ti3+ and Ti–OH are formed in the TiO2 crystal, which cause a disordered layer on the surface of the black TiO2 crystal. At the same time, the existence of defects such as oxygen vacancies and Ti3+ will make the valence and conduction bands of TiO2 appear tail bands. This greatly reduces the band gap and improves absorption. Considering the absorption effect and preparation cost comprehensively, the optimum conditions for the preparation of black TiO2 are that the hydrogenation temperature is 400 °C and the mass ratio of white TiO2 and NaBH4 is 2:1.