The intense charge migration and efficient photocatalytic NO removal of the S-scheme heterojunction composites Bi7O9I3-BiOBr

Abstract

For purpose of efficient photocatalytic removal of NO molecules, both components of bismuth-rich Bi7O9I3 and BiOBr were typically selected to create binary heterojunction composites Bi7O9I3-BiOBr (BI-BBX) through a facile in-situ synthetic protocol. These composites underwent thorough characterization using a range of analytical methods and were subjected to photocatalytic removal of NO at ppb level under visible light for the first time. These produced composites showed enhanced photocatalytic behavior and the best candidate BI-BB0.2 demonstrated the highest removal efficiency among all tested samples. Density-functional theory (DFT) calculations revealed the intense charge migration at the interface. In addition, the composites surface exhibited a propensity to adsorb and activate O2, H2O, and NO molecules, thus promoting the catalytic conversion of NO to NO2– and further NO3– species. Entrapping experiments and electron spin resonance (ESR) results demonstrated the increased generation of oxygen-containing species O2–, 1O2, and ·OH, which was attributed to the rational creation of heterojunctions with similar crystal structures and efficient migration and separation of generated charge carriers in an S-scheme model. This study provides insight into the design and development of Bi7O9I3-based composites for effective dislodge of NO upon the visible-light irradiation.