Defect engineering is important to tune the functional properties of metal oxides, such as electronic structure, charge transport, and catalytic performance. Compared with the often studied oxygen vacancies, the effect of metal vacancies on the physiochemical properties is seldom reported. Herein, we successfully synthesized undoped anatase TiO2 abundant with Ti vacancies (9.5 mol%) by solvothermal treatment of tetrabutyl titanate in an ethanol-glycerol mixture and then calcination. Both experimental measurements and DFT calculations on cell lattice parameters prove the presence of VTi in the defected TiO2. The presence of abundant VTi changes the charge density (Figure 1a) and valence band edge of TiO2, makes the c axis of anatase shrink heavily, and generates an unreported strong EPR signal at g = 1.998 even under room temperature (Figure 1b). Contrary to normal n-type and nonferromagnetic TiO2, Ti-defected TiO2 shows inherent p-type conductivity (Figure 1c) with high charge mobility, and room-temperature ferromagnetism (Figure 1d) stronger than Co-doped TiO2 nanocrystalline. Moreover, Tidefected TiO2 exhibits remarkbly higher photocatalytic performance than normal TiO2 in H2 generation (4.4-fold, Figure 1e) and organics degradation (7.0-fold for phenol) because of the more efficient charge separation and transfer in bulk and at semiconductor/electrolyte interface, which was confirmed by DFT calculations and experimental results. In addition, the surface defects are stable under the reaction conditions and long-term storage. This work demonstrates that metal vacancies can change the structure characteristics and physiochemical properties of undoped semiconductor and thus produce a new kind of functional materials for chemical and physical devices.

Influence of metal vacancy of undoped anatase TiO2 on p-type conductivity, room-temperature ferromagnetism, and remarkable photocatalytic performance

251st National Meeting (2016)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.