Synthesis of CoWO4/g-C3N4 Z-scheme heterojunction for the efficient photodegradation of diazinon with the addition of H2O2

Abstract

Pesticides are on the list of substances that are routinely monitored by agencies and organizations in various natural environments and habitats. Diazinon (DZN) is the active ingredient in more than 20 agricultural pesticides, it causes the most damage and has been prohibited in many countries around the world. The final product CoWO₄/g-C₃N₄ Z-scheme heterojunction was successfully synthesized in this work, where CoWO₄ nanoparticles were deposited on the surface of g-C₃N₄. CoWO₄/g-C₃N₄ structure allowed for the efficient separation of photo-generated electron-hole pairs, with electrons at the CoWO₄ CB migrating to the g-C₃N₄ VB and preserving the electrons at the g-C₃N₄ CB and holes in the CoWO₄ VB. The photodegradation efficiency of DZN using CoWO₄/g-C₃N₄ Z-scheme heterojunction was investigated, as compared with its precursors, such as CoWO₄, and g-C₃N₄. CoWO₄/g-C₃N₄ Z-scheme heterojunction demonstrated the highest degradation capacity for DZN removal. Based on the results, the photocatalysis of the CoWO4/g-C3N4 Z-scheme heterojunction can be recycled for the effective removal of DZN by simple washing after three runs, proving the heterojunction's stability and suggesting CoWO4 as a promising material for the removal of DZN from contaminated water sources.

Keywords: CoWO4; diazinon degradation; environment protection; g-C3N4; pesticide.