A novel ZnWO4/MgWO4 n-n heterojunction with enhanced sonocatalytic performance for the removal of methylene blue: Characterizations and sonocatalytic mechanism

Abstract

A novel ZnWO4/MgWO4 n-n heterojunction (0.9% ZnWO4/MgWO4) was fabricated successfully and characterized by different techniques. The methylene blue (MB) was removed to confirm the sonocatalytic activity by the 0.9% ZnWO4/MgWO4 composite. The sonocatalytic removal ratio of MB using MgWO4 was 40.04±4.34(%). It was significantly increased to 93.82±3.44(%) in the presence of 0.9% ZnWO4/MgWO4 composite. The significantly improved sonocatalytic performance was due to the form of n-n heterojunction, which could hinder the recombination of electron and hole (e−-h+) pairs effectively. The mechanism showed that hydroxyl radical (•OH) and h+ had important roles for the elimination of MB. Moreover, the 0.9% ZnWO4/MgWO4 composite had remarkable stability during the process of MB removal under the ultrasonic irradiation. The results suggested that the fabrication of heterojunction is a valid method to promote the sonocatalytic performance of catalyst. The results of this paper would provide valuable references for the development of new sonocatalysts used in environmental remediation.