Li2MnO3@ZrO2 heterojunctions for highly efficient catalytic photodegradation of Atrazine herbicide

Atrazine is a herbicide broadly utilized in various agricultural and food-processing applications. For the first time, novel Li2MnO3@ZrO2 (LMO@ZrO2) heterostructures were synthesized by a self-assembly route in the presence of nonionic triblock copolymer with incorporating small doses (0.5-2.0 wt%) of LMO. The synthesized samples were characterized by different instruments, which confirmed the formation of nanostructured mono-clinic LMO@ZrO2 with average crystallite sizes of 25-36 nm and high specific areas of 171-235 m(2)/g without affecting the basic structural or surface features. The synthesized photocatalysts were evaluated for mineralization and removal of Atrazine in aqueous media under visible illumination. Light absorption, photogenerated mobility, and separation were enhanced upon appropriate doping trace amounts of LMO, which lowered the bandgap to 2.16 eV and hence making them promising candidates for herbicide removal. Composite with only 1.5 wt % LMO content exhibited a full Atrazine photoelimination compared to pristine ZrO2 (66%) after 1 h of visible light illumination. The kinetic rate constant is greatly improved over LMO@ZrO2 heterostructures, the 1.5% LMO@ZrO2 composite yielding a high kinetic rate constant of 0.0434 min-1, which was increased by 2.25 -fold over pristine ZrO2 (0.0193 min(-1)). Furthermore, the LMO@ZrO2 heterojunctions also demonstrated stellar recyclability regarding the photodegradation of Atrazine. A probable mechanism for carrier charges separation through mesoporous LMO@ZrO2 heterostructures was suggested. This study supports the application of nano-heterojunction oxides for green herbicide treatments.

Automated summary

In this study, novel Li2MnO3@ZrO2 heterostructures were synthesized and showed excellent performance in the photodecomposition and removal of Atrazine, suggesting their high potential for practical applications.