N-Functionalized Ti2C MXene as a High-Performance Adsorbent for Strontium Ions: A First-Principles Study

Radionuclide sequestration through adsorption technology has attracted much attention due to its unique characteristics such as high removal efficiency, low cost, and ease of operation. In this work, the interaction mechanism of N-functionalized Ti2C MXene (Ti2CN2) as a potential adsorbent for the removal of strontium ions is investigated by using the first-principles method. Our results show that surface N atoms are connected to Sr ions by a robust chemical N–Sr bond, which provides a stronger interaction and greater capacity (1.291g g–1) of Sr ion adsorption on Ti2CN2 than Ti2C with other surficial groups O, F, and OH. Furthermore, the thermal stability of the adsorption structure of Sr on Ti2CN2 with full layer coverage at room temperature is verified by using ab initio molecular dynamics simulations. Our results are expected to provide a new perspective for the design of MXene materials as an adsorbent for radionuclides.