Water-stable S-functionalized Ti3C2 MXene for high-performance Sr and Cs adsorption

In this study, S-functionalized Ti3C2 MXene has been systematically investigated as a potential adsorbent for Sr and Cs ions using first-principles simulations. In sharp contrast to Ti3C2O2 MXene, Ti3C2S2 nanolayers remain stable in water at room temperature, which is attributed to the terminal S functional group isolating water molecules. Taking into account the factors such as exfoliation feasibility, adsorption strength, adsorption capacity and competitive ion interference, we have identified Ti3C2S2 as a highly promising adsorbent for Sr and Cs ions. Specifically, in terms of adsorption capacity, the adsorption saturation of Ti3C2S2 for Sr and Cs has been reached a coverage of 1 monolayer and 8/9 monolayer, respectively, surpassing all the commonly reported Ti3C2T2 (T = O, F, and OH) MXenes.