A superhydrophobic MOF facilitating efficient solvent-free catalytic chemical fixation of CO2 and oxidation of hydrocarbons and MOF@cotton@starch composite-based selective sensing of a herbicide

Abstract

Modern-day environmental pollution does not end with only air pollution by harmful gases. Issues also arise due to dust particles released by industry and motor vehicles. Regular use of herbicides, fungicides, and pesticides to increase the production of foodstuffs in agricultural fields also enhances the risk of soil and aquatic environmental pollution. Therefore, the systematic development of multi-functional materials for the catalytic conversion of toxic gases and hydrocarbons into value-added products under mild conditions, selective detection, and quantification of toxic organic pollutants in environmental water bodies are crucial to maintaining a sustainable environment. Herein, we have strategically engineered a highly robust, fluorine-rich, Zr(IV)–organic framework (1) and, desolvated (1′) to address three emerging environmental issues. This is the first recyclable metal–organic framework (MOF) catalyst (1′) where the Lewis basic nature of fluorine atoms and the Lewis acidic nature of the Zr(IV) sites are utilized for the mild pressure, solvent-free entrapping of CO₂ to epoxides with various kinetic dimensions in high yields. The hydrophobic cavity of 1′ also facilitated better conversions of hydrocarbons into their respective alcohols/ketones compared to non-hydrophobic MOF under aerobic oxidation conditions with recyclability. Notably, for the first time, selective, rapid (response time <5 s) and nanomolar (LOD = 1.1 nM) fluorescence-based detection of aclonifen (ACF) herbicide was performed using 1′ in various environmental water samples, at different pH conditions, and also in variety of food and vegetable extracts. Moreover, a reusable 1′@starch@cotton composite was fabricated for the on-site, naked-eye detection of ACF under UV light. Additionally, a detailed investigation of the mechanistic pathways of all the proposed applications was performed experimentally and theoretically.