Structural-Controlled Synthesis of Highly Efficient Visible Light TiO(2) Photocatalyst via One-Step Single-Mode Microwave Assisted Reaction

TiO(2) with different chemical structures are successfully synthesized via a one-step single-mode magnetic microwave (SMMW) assisted process, during where Ti selectively oxidizes in magnetic field under Ar-O(2) mixed atmosphere. The chemical state and band structure of the as-prepared TiO(2) are well-controlled by changing the volume fraction of O(2) (φO(2)) during SMMW synthesis. Ti(3+) self-doped TiO(2) (TiO(2−x), 0 < x < 2) is synthesized under lower φO(2), while TiO(2) with specific core/shell structure (TiO(2+y) core/TiO(2−x)-TiO(2+z) shell) is observed under higher φO(2). The as-synthesized TiO(2) with controlled structures show sufficient light absorption in visible region and quite narrow bandgap (2.05 eV∼), whose value can be also tuned by φO(2) during SMMW synthesis. In addition, the synthesized TiO(2) exhibits highly efficient photocatalytic performance towards the degradation of Rhodamine B under UV and visible light irradiation. The formation mechanism for different structural TiO(2) can be attributed to the specific rapid heating and cooling dynamics induced by SMMW irradiation.