Defect engineering in novel broad-band gap hexaaluminate MAl12O19 (M=Ca, sr, Ba)-Based photocatalysts Boosts Near ultraviolet and visible light-driven photocatalytic performance

Abstract

The M(M = Ca, Sr, Ba)Al12O19, MAl12O19:Mn, and MAl12O19:Mn:Ce photocatalysts have been synthesized successfully through a polyacrylamide gel method. The Mn ion prefer to occupy the position of Al ion in SrAl12O19, while there is no evidence revealing that the Mn ion occupies the Al ion position in (Ca, Ba)Al12O19. The one-pot polyacrylamide gel method utilizes the fast nucleation, growth, and heterostructure construction of the MAl12O19 to deliberately immobilize the desired fine spherical particles of Mn3O4 or Mn3O4 and CeO2 on the surface of MAl12O19 nanosheets. All the MAl12O19:Mn:Ce photocatalysts exhibited outstanding photocatalytic activities for the degradation of methylene blue than that of M(M = Ca, Sr, Ba)Al12O19 and MAl12O19:Mn photocatalysts under near ultraviolet and visible light irradiation. The improved photocatalytic activity of n-p-n type double p-n heterojunction MAl12O19:Mn:Ce photocatalysts can be attributed to the synergistic effect among the M(M = Ca, Sr, Ba)Al12O19, CeO2, and Mn3O4, which not only improves the visible light response ability and enhances the migration and separation efficiency of charge carriers but also retains the strong the oxidation or reduction capacity of charge carriers. This work may provide a n-p-n type double p-n heterojunction photocatalytic system into the development and design high efficient heterojunction photocatalysts for the degradation of organic dyes and environmental protection.