Understanding Functionalization of Titanium Carbide (MXene) with Quinones and Their Pseudocapacitance

Here, the interaction mechanism of 1-aminoanthraquinone (AQ) on Ti3C2Tx MXene by noncovalent (AQ@Ti3C2Tx) and covalent (AQ-Ti3C2Tx) functionalization is reported. Spectroscopic, X-ray, and scattering techniques confirmed noncovalent functionalization of AQ on Ti3C2Tx MXene without its catalytic decomposition, resulting in intercalation and interaction of AQ with Ti3C2Tx MXene. Diazonium reaction was further used to covalently functionalize AQ molecules on Ti3C2Tx MXene. Optimized AQ-Ti3C2Tx freestanding electrodes of ~44 ?m thickness delivered capacitance of ~300 F/g and improved rate performance compared to the pristine counterpart (Ti3C2Tx) due to carbonyl redox of AQ and improved ionic transport between MXene layers due to pillaring of AQ molecules.