SnO2 quantum dots synthesized with a carrier solvent assisted interfacial reaction for band-structure engineering of TiO2 photocatalysts

Abstract

A simple, fast, room temperature, surfactant-free, carrier solvent assisted interfacial reaction method is developed for size-controllable syntheses of SnO2 quantum dots (QD). Narrowly size-ranged SnO2 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 SnO2 QDs, when decorated onto the surfaces of TiO2 nanoparticles, enable precise engineering of the band structure of the TiO2 nanoparticles. The band structure of the SnO2 QD decorated TiO2 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 TiO2 nanoparticles. The photocatalytic degradation efficiency of TiO2 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 SnO2 QD decoration. © 2014 American Chemical Society.