Oxygen vacancy-dependent photocatalytic activity of well-defined Bi2Sn2O7−x hollow nanocubes for NOx removal

Abstract

Intricate engineering of oxygen vacancies (OVs) to trap kinetically diffusible rarefied NO gas and to enhance the population of long-lived electrons remains a great challenge for NO removal in outdoor atmosphere. In this study, OV-engineered Bi₂Sn₂O_7−x hollow nanocubes with distinct Sn/Bi-adjacent OVs were tightly managed and synthesized. Theoretical calculations and experimental studies revealed that not all types of OVs were beneficial for increasing the photoactivity owing to their different effects on the band structure and carrier diffusion path. Bi₂Sn₂O_7−x with Sn-adjacent OVs could serve as adsorption sites, boosting rarefied NO enrichment and electron–hole separation. However, Bi₂Sn₂O_7−x with Bi-adjacent OVs exhibited an opposite effect owing to increased charge recombination centers. Our findings highlight the importance of the character of OVs for efficient interface electron activation and for the removal of ambient rarefied gaseous pollutants.