Ultrasonic-assisted synthesis Zn0.78Cd0.22S/Bi2MoO6 heterojunction to improve photocatalytic performance for hexavalent chromium removal and hydrogen peroxide production

Abstract

Due to the wide application of hydrogen peroxide, the demand for hydrogen peroxide is increasing day by day all over the world. However, the traditional preparation method of hydrogen peroxide has many inevitable disadvantages, such as high energy consumption, low yield, and the by-products during the reaction process have great harm to the environment. So, it is emergent to search for new efficient and environmentally friendly ways to produce hydrogen peroxide. The stable semiconductor Zn0.78Cd0.22S and bismuth-based material Bi2MoO6 were combined to form heterojunction for the first time. The heterojunction photocatalyst Zn0.78Cd0.22S/Bi2MoO6 is mainly applied to the treatment of heavy metal hexavalent chromium in wastewater and photocatalytic hydrogen peroxide production. The successful construction of heterojunction greatly reduces the recombination rate of photogenerated electrons and photogenerated holes, resulting in more electrons reducing oxygen to generate hydrogen peroxide and reducing Cr6+ to Cr3+ in the conduction band of Zn0.78Cd0.22S, and more photogenerated holes oxidizing water molecules to obtain hydrogen peroxide in the valence band of Bi2MoO6. Furthermore, compared with the hydrothermal method to combine Zn0.78Cd0.22S and Bi2MoO6, the ultrasonic method used here prevents the synthesis of Bi2S3.