Boosted photocatalytic NO removal performance by S-scheme hierarchical composites WO3/Bi4O5Br2 prepared through a facile ball-milling protocol

Abstract

• Composites WO 3 /Bi 4 O 5 Br 2 were constructed via a facile ball-milling protocol. • The structure-effect relationship was successfully established. • These binary composites showed enhanced photocatalytic NO removal efficiencies. • A plausible S-scheme model was speculated in photocatalysis mechanism. It is crucial to develop an efficient system of high photocatalytic capability over NO removal and simultaneous avoidance of toxic NO 2 formation. In this study a serious of hierarchical composites WO 3 /Bi 4 O 5 Br 2 (WB) were successfully fabricated by a facile ball-milling protocol and systematically characterized by various analytical techniques. Both expected ingredients were realized and coexisted in composites to generate heterojunction structures by microstructural analyses. Under visible light irradiation, these samples were exposed to photocatalytic removal of NO measurements, where aforementioned binary hierarchical WB composites showed reinforced NO removal efficiency with the high selectivity for NO 3 – /NO 2 – species in comparison to bare WO 3 and Bi 4 O 5 Br 2 , mainly associating to the efficient migration and spatial segregation of charge carries through heterojunction domains with suitable phase composition instead of the slightly varied visible light absorption and specific surface area. In addition, a possible photocatalysis mechanism was deduced in a S-scheme model by active species determination and band structures estimation of these robust catalysts. This investigation shed light on the facile fabrication of hierarchical composites via the ball-milling treatment with enhanced photocatalytic removal of low concentration NO in ppb level under visible light.