Enhanced mercuric ions reduction over mesoporous S-scheme LaFeO3/ZnO p-n heterojunction photocatalysts

Background: The separation of heavy metal ions from industrial wastewater is a great challenge regarding environmental remediation. Methods: Following this, a Sol-gel technique was successfully utilized to synthesize novel mesoporous LaFeO3/ZnO nanocomposites containing varying concentrations of LaFeO3 nanoparticles. Mercury ions (Hg2+) were photo-reduced over the prepared mesoporous LaFeO3/ZnO heterojunctions in the presence of HCOOH which plays the role of the hole scavenger. Significant finding: Illumination by visible light showed that mesoporous LaFeO3/ZnO nanocomposite containing 3.0 wt.% LaFeO3 maintained a noticeable ability of mercury ions photo-reduction. The complete photo-reduction of mercury ions was achieved and was estimated as 16.6 times greater when compared with pure ZnO after 30 min of exposure. Major factors that contributed to the remarkable mercury ions photoreduction ability of LaFeO3/ZnO nanocomposite heterojunction system are summarized as the enhanced visible light absorption, effective separation of generated charges, distinct large surface area, and distinguished mesoporous texture. The outcomes presented here represent an example of an outstanding approach for adequate removal of mercury ions that could be adopted efficiently in various industrial fields.