Two-step method to prepare the direct Z-scheme heterojunction hierarchical flower-like Ag@AgBr/Bi2MoO6 microsphere photocatalysts for waste water treatment under visible light

In this study, a novel Z-scheme Ag@AgBr/Bi2MoO6 heterojunction photocatalyst was synthesized via a two-step process: the hierarchical flower-like Bi2MoO6 microspheres were synthesized; Ag and AgBr were decorated to Bi2MoO6 microspheres. As an environmentally friendly catalyst, it can selectively achieve the conversion of organic pollutants without producing by-products via solar energy irradiation. Visible light excites Bi2MoO6 and AgBr nanoparticles to generate electron-hole pairs. Due to the high conductivity of Ag nanoparticles, electrons are conducted to AgBr via Ag nanoparticles and recombined electrostatically with hole of AgBr, which effectively inhibits the recombination of photo-generated hole-electron pairs. The unique electron transport path and flower-like microsphere structure allow free radicals to fully react with organic matter. The enhanced photocatalytic performance of the photocatalyst was evaluated by photodegradation of RB-19 under visible-light irradiation. After 120 min of irradiation, the degradation rate of Ag@AgBr/Bi2MoO6 to RB-19 reached 98.7%, which is much greater than the degradation performance of AgBr/Bi2MoO6 and Bi2MoO6. At the same time, after five cycles of testing, the ternary composite still has a degradation rate of 70%. In addition, the results of capture experiments showed that center dot O-2(-) and h(+) are the main active substances for the decomposition of RB-19 dye molecules. The Mott-Schottky diagram explains the band structure of the catalyst. Thus, this study provides a new method for preparing Z-type photocatalysts and opens up new possibilities for selective organic conversion.