Heavy-Metal Adsorption Behavior of Two-Dimensional
Alkalization-Intercalated MXene by First-Principles Calculations
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Abstract
The
two-dimensional (2D) layered MXene (Ti<sub>3</sub>C<sub>2</sub>(OH)<sub><i>x</i></sub>F<sub>2–<i>x</i></sub>)
material can be alkalization intercalated to achieve heavy-metal
ion adsorption. Herein the adsorption kinetics of heavy-metal ions
and the effect of intercalated sites on adsorption have been interpreted
by first-principles with density functional theory. When the coverage
of the heavy-metal ion is larger than 1/9 monolayer, the two-dimensional
alkalization-intercalated MXene (alk-MXene: Ti<sub>3</sub>C<sub>2</sub>(OH)<sub>2</sub>) exhibits strong heavy-metal ion absorbability.
The hydrogen atoms around the adsorbed heavy-metal atom are prone
to form a hydrogen potential trap, maintaining charge equilibrium.
In addition, the ion adsorption efficiency of alk-MXene decreases
due to the occupation of the F atom but accelerates by the intercalation
of Li, Na, and K atoms. More importantly, the hydroxyl site vertical
to the titanium atom shows a stronger trend of removing the metal
ion than other positions
