Simultaneous Delamination and Rutile Formation on the Surface of Ti₃ C₂ T_x MXene for Copper Adsorption

In this work, we studied the formation of the rutile phase of titanium dioxide (TiO₂ ) on delaminated MXene (d-Ti₃ C₂ T_x ) flakes by the reaction of Ti₃ C₂ T_x with amino acids in water. Three types of amino acids with varied side-chain polarity were used to delaminate Ti₃ C₂ T_x . d-Ti₃ C₂ T_x flakes formed stable colloidal solutions due to the negative surface charges of chemisorbed amino acids on the d-Ti₃ C₂ T_x . Rutile formed on d-Ti₃ C₂ T_x at room temperature upon the intercalation of aromatic amino acids and subsequent sonication of the solution, while flakes intercalated with aliphatic amino acids did not oxidize. X-Ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy revealed the nanosize rutile formation on the surface of Ti₃ C₂ T_x flakes. The XPS results indicated the surface functionalization of histidine on d-Ti₃ C₂ T_x flakes. As-synthesized histidine functionalized rutile TiO₂ @d-Ti₃ C₂ T_x hybrid was used for adsorption of Cu²⁺ ions from aqueous solution with a maximum uptake of 95 mg g^-1 .