SnO2 Quantum Dots Synthesized with a Carrier Solvent Assisted Interfacial Reaction for Band-Structure Engineering of TiO2 Photocatalysts

A simple, fast, room temperature, surfactant-free, carrier solvent assisted interfacial reaction method is developed for size-controllable syntheses of SnO 2 quantum dots (QD). Narrowly size-ranged SnO 2 QDs with average diameters of 2–2.7 nm, corresponding to energy band gaps of 5.7–4.39 eV, are produced at room temperature within 30 min through precursor concentration adjustment. These SnO 2 QDs, when decorated onto the surfaces of TiO 2 nanoparticles, enable precise engineering of the band structure of the TiO 2 nanoparticles. The band structure of the SnO 2 QD decorated TiO 2 nanoparticles can be controlled to achieve not only enhanced charge separation but also generation of extra oxidizing species, peroxy radicals, both beneficial for boosting the photocatalytic performances of the TiO 2 nanoparticles. The photocatalytic degradation efficiency of TiO 2 toward Rhodamine B, in terms of the apparent reaction rate constant, is significantly improved from 0.025 to 0.055 min –1 with the band structure engineering achieved through SnO 2 QD decoration.