Preparation of (B,N)-codoped TiO2 micro-nano composite powder using TiBN powder as a precursor

(B,N)-codoped TiO2 was prepared by the oxidation method using TiBN powder as a precursor. The oxidation of TiBN powder particles started with the surface, producing a high-Ti low-O compound Ti2O3. Meanwhile, accompanied by the migration and oxidation of B, the oxidative process gradually extended towards the interior, giving rise to the formation of (B,N)-codoped TiO2. XRD analysis revealed that, in oxidative products, the residual TiBN phase was structurally similar to Ti4N3B2, suggesting that Ti had diffused and migrated outwards from TiBN. On this basis, an oxidative model was built for TiBN particles. The oxidation of TiBN consisted of two processes: chemical reaction (TiBN→Ti2O3→TiO2) and organizational structure evolution (TiBN→Ti4N3B2). The prepared TiO2 was dominated by rutile form and also contained small amounts of anatase and residual TiBN. (B,N) Codoping increased the lattice parameter of rutile TiO2. Organizational structure was found to be related to the parameters of the oxidative process. Pure rutile TiO2 could be obtained from TiBN powder under 800°C + 2h oxidative treatment, and the interplanar spacings of its (110), (101), (211), and (111) planes were 0.324877 nm, 0.24875 nm, 0.16874 nm, and 0.21873 nm, respectively. These interplanar spacings were greater than the interplanar spacings of TiO2 produced through the oxidation of TiN under equal conditions, which was attributable to (B,N) codoping in TiO2. According to direct observations by high-resolution transmission electron microscopy (HRTEM), the organizational structure of TiO2 particles demonstrated the fine size and elliptical boundary and contained amorphous layers. This study offers a new approach to (B,N) codoping in TiO2. The (B,N)-codoped TiO2 with high photocatalytic efficiency obtained in this study can be applied in environmental and energy fields.