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 O2−-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 MSnO3 catalyst is served to turn light into chemical energy by improving species chemisorption on the surface. CaSnO3 with the Ca/Sn ratio of 2.7 (2.7-CaSnO3) rich in oxygen vacancies exhibited a high photocurrent performance and an efficient photocatalytic activity. A superior photo efficiency is achieved for 2.7-CaSnO3, which reduces 93.9% MB dyes within 30 min under 100 mW/cm2 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 H2 and 62.0 μmol h−1 g−1 of O2 are realized over 2.7-CaSnO3. The chemisorption improved by oxygen defects in 2.7-CaSnO3 enables the transfer of photogenerated electrons to oxygen species in space. Therefore, oxygen molecules are activated into superoxide radicals on the oxygen defect-rich MSnO3 successfully. After more oxygen defects doping, the hydrogen evolution rate increases from 553.3 to 1152.7 μmol h−1 g−1, while O2 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-CaSnO3.