Simultaneous Delamination and Rutile Formation on the Surface of Ti3 C2 Tx 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 Tx ) flakes by the reaction of Ti3 C2 Tx with amino acids in water. Three types of amino acids with varied side-chain polarity were used to delaminate Ti3 C2 Tx . d-Ti3 C2 Tx flakes formed stable colloidal solutions due to the negative surface charges of chemisorbed amino acids on the d-Ti3 C2 Tx . Rutile formed on d-Ti3 C2 Tx 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 Tx flakes. The XPS results indicated the surface functionalization of histidine on d-Ti3 C2 Tx flakes. As-synthesized histidine functionalized rutile TiO2 @d-Ti3 C2 Tx hybrid was used for adsorption of Cu2+ ions from aqueous solution with a maximum uptake of 95 mg g-1 .