Uncovering the synergy between Mn substitution and O vacancy in ZnAl-LDH photocatalyst for efficient toluene removal

Metal-substituted layered double hydroxide (LDH) photocatalysts are considered to have potential advantages in air pollution control. However, the current understanding of effect mechanism of metal substitution on microstructure and photocatalytic performance is still poor. Herein, we prepared Mn-substituted ZnAl-LDH and found that Mn substitution can effectively promote the surface O vacancy formation. Combining experiments and theoretical calculations, it was confirmed that the synergy between Mn substitution and O vacancy is the essential reason for the enhanced photocatalytic performance of LDH. The main function of Mn substitution is to regulate the band gap structure and improve the separation efficiency of photogenerated carriers, while the contribution of O vacancy is focused on strengthening the adsorption and activation of O2 molecules, thereby promoting the formation of reactive oxygen species. During the photocatalytic degradation of toluene, the synergistic effect not only promotes the absorption of pollutants, but also intensifies the ring-opening reaction.