Multithiol Functionalized MXene Gel and Its Effective Adsorption Behavior for Cr(VI)

Hexavalent chromium (Cr(VI)) is a highly toxic heavy metal contaminant commonly used in industrial applications, posing significant risks to human health and environmental sustainability due to its persistence and difficulty in degradation. Transition metal carbide (MXene) is an emerging two-dimensional material that has gained considerable attention for its potential in water pollutant removal. However, poor MXene stability and limited functional groups restrict its specific adsorption of target metal ions such as Cr(VI). Herein, a novel functionalized three-dimensional MXene composite gel (M/D/P) was synthesized via a photo-induced thiol-ene click reaction using MXene as the framework material. The multithiol-functionalized framework introduces abundant thiol groups, which facilitate the reduction of Cr(VI) to less toxic Cr(III) and enable chelation of Cr(III) with the adsorbent, driven by proton depletion during reduction. The adsorption behavior follows pseudo-second-order kinetics and the Langmuir model, indicating a chemical adsorption process. The maximum removal capacity reaches 347.71 mg·g − 1 , and the gel maintains 80% of its initial adsorption capacity after five cycles. The synergistic adsorption-reduction mechanism, involving electrostatic attraction, reduction, covalent bonding, and chelation, highlights M/D/P as a promising MXene-based adsorbent for water treatment applications. Graphical A multithiol-functionalized MXene composite gel (M/D/P) is synthesized via photo-induced thiol-ene click reaction. The abundant thiol groups enable synergistic adsorption–reduction of Cr(VI) through electrostatic attraction, chemical reduction, and chelation. The material achieves 374.71 mg·g − 1 removal capacity with excellent reusability.