Band engineering of Ag-Bi12GeO20-Bi2WO6 composite photocatalyst: Interface regulation and enhanced photocatalytic performance

Novel Ag-Bi12GeO20-Bi2WO6 heterojunction was developed and demonstrated as an excellent photocatalyst to degrade the Rhodamine B (RhB) aqueous solution with the help of UV-vis light. The Bi12GeO20-Bi2WO6 heterojunction was firstly fabricated through a facile partial chemical conversion strategy, employing pre-prepared Bi2WO6 nanosheets as Bi3+ source. Under the high temperature and high pressure environments, partially released Bi3+ ions derived from the Bi2WO6 nanosheets could react with Ge source, leading to the formation of Bi12GeO20 tetrahedrons. Meanwhile, the remaining Bi2WO6 nanosheets were also anchored in situ onto the surface of the Bi12GeO20 tetrahedrons, thus forming a unique heterojunction with face-to-face connection form of heterogeneous interface. After the loading of Ag nanoparticles, the as-obtained Bi12GeO20-Bi2WO6 heterogeneous structure exhibited outstanding catalytic efficiency toward the decomposition of RhB. Due to the structural and compositional features such as matching band structure, intimate interfacial contacts, unique interface contact structure and the well-known schottky barriers, the photo-generated charges of the resulting ternary composite photocatalyst was efficiently separated and thus exhibited improved catalytic activity. This rational construction of Bi12GeO20-Bi2WO6 ternary photocatalytic system based on energy band engineering is ingenious and can provide a mirror for the fabrication of other photocatalytic materials.