Incorporating Li2MnO3 nanocatalysts with mesoporous ZnWO4 enhances charge mobility and promotes the photocatalytic oxidation of atrazine

Abstract

Atrazine is an effective herbicide with universal publicity for its vigorous cytotoxicity as inhibitor of photosynthesis process and the degradation of atrazine is considered a serious challenges. Herein, S-scheme heterojunction Li₂MnO₃/ZnWO₄ photocatalyst was constructed by the impregnation and sol-gel path for promoting atrazine degradation upon visible illumination. XRD and TEM images results verified Li₂MnO₃ and ZnWO₄ phases were successfully constructed with the monoclinic structure and monoclinic wolframite. HRTEM images of Li₂MnO₃/ZnWO₄ nanocomposite showed that the interplanar fringes of 0.429 nm and 0.46 nm were related to the planes of (022) and (100) for monoclinic phases of Li₂MnO₃ and ZnWO₄, respectively. The incorporation of Li₂MnO₃ NPs into mesoporous ZnWO₄ matrix extended light absorption to support photocatalytic ability. The 10 % Li₂MnO₃/ZnWO₄ nanocomposite demonstrated potent destruction of atrazine up to 100 % within 50 min, which was 20 multiples higher than that of pristine ZnWO₄ NPs. The rate constant (k) for the atrazine degradation over 10 % Li₂MnO₃/ZnWO₄ nanocomposite (0.051 min⁻¹) was nearly enhanced 15 multiples greater than of pristine ZnWO₄ NPs (0.0034 min⁻¹). The k of 10 % Li₂MnO₃/ZnWO₄ photocatalyst (0.051 min⁻¹) was the highest compared with other photocatalysts. The enhancement photocatalytic performance of Li₂MnO₃/ZnWO₄ nanocomposite was explained by the outstanding absorption light capacity and enhanced separation of photoindiced charge in Li₂MnO₃/ZnWO₄ S-scheme heterojunction photocatalyst. Also, the synergistic impact between Li₂MnO₃ and ZnWO₄ could enhance charge migration and transport, thus promoting the photocatalytic efficiency. This work offers an efficient design toward strongly integrated nanocomposite photocatalysts for detoxification of organic pollutants under visible light.