High photocatalytic activity of rutile TiO2–BiOBr composites via an in situ synthesis approach

Abstract

It is well known that rutile TiO₂ has extremely inferior photocatalytic performance due to lower electron mobility and specific surface area than anatase TiO₂. In addition, the photocatalytic performance of BiOBr is also not satisfactory due to small specific surface area and positive conduction band position. However, when the two above-mentioned catalysts were combined to form composites via an in situ synthesis approach, resulting that rutile TiO₂–BiOBr composites exhibited a superior performance of almost the same photocatalytic effect as anatase TiO₂–BiOBr composites, of which the apparent rate constant of MO photodegradation was approximately 1.6 times larger than that of anatase TiO₂ and 6.3 times larger than that of BiOBr. To further investigate the reasons, the samples were characterized by XRD, TEM, DRS, EIS, BET, PL, etc. Although RT + BOB has better EIS or PL data than AT + BOB, the specific surface area of AT + BOB is larger than that of RT + BOB. In addition, it can be deduced that photogenerated holes are the dominant active species of TiO₂–BiOBr composites by active species trapping experiments. Finally, a possible mechanism for the enhancement of photocatalytic performance of rutile TiO₂–BiOBr composites was proposed.