Inorganic-organic TiO2/Bi-MOF Z-scheme heterojunction photocatalysts for promoting NO deep oxidation

Abstract

Excessive emission of nitrogen oxides (NO_x) has upset the balance of the natural nitrogen cycle, leading to environmental pollution problems such as acid rain, haze and greenhouse effect. In this study, loading TiO₂ on the surface of bismuth-based metal MOFs was proposed to form inorganic-organic TiO₂/Bi-MOF Z-scheme heterojunction composites for NO removal. The results showed that TiO₂/Bi-MOF-0.3 (T/B-0.3) possessed excellent photocatalytic activity, with a single NO removal efficiency of 61.7 % for 30 min and maintained 52.5 % removal efficiency of NO even after five cycles. The boost in photocatalytic activity stems from the heterostructure of TiO₂ on the Bi-MOF surface, which enhances the movement and separation of photogenerated charge carriers. In addition, the formation of Z-scheme heterojunctions contributes to the production of more active species for oxidizing NO Possible NO oxidation mechanisms based on energy band structure theory, active species, and in situ DRIFTS are also proposed. This research may introduce an innovative approach for the development of photocatalysts aimed at addressing atmospheric pollutants.