Novel plate-on-plate hollow structured BiOBr/Bi2MoO6p-n heterojunctions: In-situ chemical etching preparation and highly improved photocatalytic antibacterial activity

Abstract

In this study, a novel plate-on-plate hollow structured BiOBr/Bi2MoO6p-n heterojunction with rich oxygen vacancies (OVs) was systematically constructed by an in-situ ion exchange method. The structure, morphology, photoabsorption ability, and surface properties of BiOBr/Bi2MoO6 were characterized, showing an etching process of BiOBr nanoplates (NPs) by molybdate to form BiOBr/Bi2MoO6 plate-on-plate hollow heterostructures (BM PHs). A feasible formation mechanism was proposed by regulating the concentration of molybdate and reaction times. The introduction of Bi2MoO6 in BiOBr NPs was proved to play a significant role in affecting the crystal growth and photocatalytic activity of BM PHs, which displayed a greatly enhanced photocatalytic antibacterial performance under visible light irradiation compared to pure BiOBr and Bi2MoO6. The highly efficient photocatalytic performance can be attributed to the synergistic effects of the fabricated p-n heterojunction combined with massive OVs, leading to the fast separation of photoinduced charge carriers, which were subsequently verified by the photoelectrochemistry (PEC) and photoluminescence (PL) measurements. In addition, the photocatalytic mechanism was discussed and deduced based on the active spices trapping and electron spin resonance (ESR) tests as well as DFT theory calculation, illustrating the primary roles of OH, O2− and h+ and charge migration route during the photocatalytic process of BM PHs. This study provides a promising strategy for constructing novel heterojunctions with highly efficient photocatalytic performance.