Dual Z-scheme heterojunction NH₂-UiO-66/BiOBr/AgI with enhanced performance on visible light driven elimination of tetracycline and Cr(VI)

To tackle the challenges for photocatalysts efficacy enhancement, a novel dual Z-scheme NH2-UiO-66/BiOBr/AgI (NUBA) ternary composite photocatalyst was constructed and systematically characterized. NUBA displayed much higher visible light photocatalytic efficacies in tetracycline (TC) degradation and Cr(VI) reduction than the corresponding single components and binary composites. With employment of NUBA and visible light irradiation, 97% of TC was removed in 40 min whereas 96% of Cr(VI) was reduced in 30 min for the individual TC and Cr(VI) solution. Furthermore, NUBA manifested superior efficacy in simultaneously and synergistically removing TC/Cr(VI) mixture than for corresponding single pollutant. A dual Z-scheme charge transfer mechanism was established which confirmed that center dot O-2(-) and h(+) dominated TC degradation, whereas photo-induced electrons implemented Cr(VI) reduction. The promoted activity of NUBA was attributed to the synergism through incorporating the advantages furnished by individual components with rich charge transfer channels, larger specific surface areas, and strengthen visible light harvest, thus preeminently reinforced the production, separation and transportation of photogenerated charge carriers. NUBA demonstrated good anti-interfering ability and wide applicability for organic pollutants degradation, along with exceptional stability and durability for cyclic use. This work may supply an inspiration for the construction of efficacious dual Z-scheme photocatalytic systems for wastewater remediation.