Effect of oxide defect on photocatalytic properties of MSnO3 (M = Ca, Sr, and Ba) photocatalysts

Abstract Since energy transfer to oxygen species is generally considered to be the critical step during the O 2 − -driven photocatalytic reaction, it is important to develop approaches to design the oxygen defects induced photocatalysts to improve the performance of oxygen chemisorption. Here we report that a new strategy of oxide defect controlled MSnO 3 catalyst is served to turn light into chemical energy by improving species chemisorption on the surface. CaSnO 3 with the Ca/Sn ratio of 2.7 (2.7-CaSnO 3 ) rich in oxygen vacancies exhibited a high photocurrent performance and an efficient photocatalytic activity. A superior photo efficiency is achieved for 2.7-CaSnO 3 , which reduces 93.9% MB dyes within 30 min under 100 mW/cm 2 white LED light irradiation, approximately 3.2 times larger than its stoichiometric one. Under the same LED light irradiation, 577.4 μmol h −1  g −1 of H 2 and 62.0 μmol h −1  g −1 of O 2 are realized over 2.7-CaSnO 3 . The chemisorption improved by oxygen defects in 2.7-CaSnO 3 enables the transfer of photogenerated electrons to oxygen species in space. Therefore, oxygen molecules are activated into superoxide radicals on the oxygen defect-rich MSnO 3 successfully. After more oxygen defects doping, the hydrogen evolution rate increases from 553.3 to 1152.7 μmol h −1  g −1 , while O 2 production rates increases from 62.0 to 129.1 μmol h −1  g −1 . The hydrogen reduction treatment further revealed that the enhancement of both hydrogen and oxygen evolution was realized by introducing more oxygen vacancies into 2.7-CaSnO 3 .