Nitrate promoted ATZ degradation in Z-scheme Cs3Bi2I9/BiVO4 photocatalytic system: Coupling ·OH and RNS mediated reduction and oxidation

Abstract

Nitrate, widely present in water, can be excited by UV light and generate reactive nitrogen species (RNS) etc., facilitating pollutants selective degradation. In this work, the promoting effect of nitrate on atrazine removal in the Z-scheme Cs3Bi2I9/BiVO4 (CBI/BVO) photocatalytic system was studied. The CBI/BVO composite utilized CBI and BVO excitation to enhance photogenerated carriers production, and the Z-scheme heterojunction to increase photoinduced carriers separation yield, with a maximum value of 15.41 times that of pure BVO, releasing CBI electrons and BVO holes with powerful redox ability. Thanks to nitrate addition, the atrazine degradation improved, whose kinetic constant was 14.46 and 2.37 times higher than that of nitrate photolysis and 0.32-CBI/BVO photocatalysis. DFT, HPLC-MS, EPR, and toxicity assessments indicated the electron rich portion of atrazine and its intermediates were susceptible to RNS attack and underwent dechlorination, that combined with the oxidation brought by ·OH, synergistically promoting atrazine degradation, mineralization, and detoxification.