Porous core-shell TixSn1-xO2 solid solutions with broad-light response: One-pot synthesis and ultrahigh photooxidation performance

Low light-absorption capacity and separation efficiency of photo-generated charges are two major limit factors to achieve high performance of photocatalysts. Herein, porous core-shell TixSn1-xO2 solid solutions with effective light-absorption capacity and charge separation are fabricated through one-pot mild solvothermal method without any surfactant and template. The self-development mechanism of the porous core-shell microspheres includes prior Ti-alkoxide hydrolysis and the spontaneous nucleation of TixSn1-xO2 combined with Ostwald ripening. Interestingly, although both TiO2 and SnO2 are wide band gap semiconductors, the prepared yellow TixSn1-xO2 solid solutions are of controllable band structure and broad-light response capacity. When Ti:Sn molar ratio is 7:3, the Ti0.7Sn1-xO2 sample shows the highest MO-photodegradation rate constant of 0.62 min(-1) under UV irradiation, exceeding that of commercial TiO2 (0.04 min(-1)) by more than 15 times. Particularly, the sample also exhibits ultrahigh photocatalytic activity in MO-photodegradation (0.038 min(-1)) and As(III) removal (up to 100%) under visible-light (>= 420 nm) irradiation. The mechanism study reveals that due to the proper redox potential of Sn-IV/Sn-II and the structural defects (e.g., oxygen vacancies) caused by lattice distortion, the photogenerated electrons would be trapped and the holes act as the main active species for the photooxidation reaction of MO and As(III) over TixSn1-xO2 photocatalysts.