In-situ fabrication of AgI/AgnMoxO3x+n/2/g-C3N4 ternary composite photocatalysts for benzotriazole degradation: Tuning the heterostructure, photocatalytic activity and photostability by the degree of molybdate polymerization

Abstract

The degree of molybdate polymerization significantly affects the photocatalytic properties of molybdate-based photocatalysts. However, few studies have focused on this aspect. Herein, novel AgI/AgnMoxO3x+n/2/g-C3N4 ternary composites were constructed via a facile two-step in-situ synthesis approach. Photocatalytic activity of AgI/AgnMoxO3x+n/2/g-C3N4 was tested for the degradation of benzotriazole (BTA) in aqueous solution. We illustrated the intrinsic dependence of the band structure, dual built-in electric field, charge transfer mechanism and photocatalytic activity of AgI/AgnMoxO3x+n/2/g-C3N4 on the degree of molybdate polymerization. Tuning the polymerization degree of molybdate constituent in AgI/AgnMoxO3x+n/2/g-C3N4 can produce more advantageous band structures and dual built-in electric fields with different directions at the intimate contact interface. The charge transfer mechanism of undergoes a transition from dual type-II to a hybrid of type-II and Z-scheme and then to dual direct Z-scheme with the increase of the degree of molybdate polymerization, which can simultaneously enhance the photocatalytic activity and photostability of the AgI/AgnMoxO3x+n/2/g-C3N4 ternary heterojunction photocatalysts, achieving the effect of killing two birds with one stone. It was confirmed that AgI/AgnMoxO3x+n/2/g-C3N4 can be activated by visible light and employed as effective photocatalyst in photocatalytic degradation of BTA.