Phosphate-Grafted Ti3C2Tx Nanosheets for Enhanced Dispersion in Nonpolar Solvents and Improved Conductivity and Stability

Ti3C2Tx MXene’s industrial adoption is hindered by its instability in humid environments and poor dispersion in nonpolar processing solvents, while conventional surface functionalization strategies severely degrade its high electrical conductivity. Herein, we address this challenge through a ligand engineering strategy using phosphate-grafted organic ligands with tailored chain lengths. Among these, phenylphosphonic acid (PhPA) is identified as the optimal ligand, enabling stable dispersion of Ti3C2Tx in 13 organic solvents (spanning from polar to nonpolar) while retaining 47.8% of pristine conductivity (14.38 × 104 S m–1), which is a significant improvement over existing methods. The PhPA-modified Ti3C2Tx exhibits exceptional environmental stability, maintaining 93% of its electromagnetic interference shielding efficiency after 180 days in humid air and showing resistance to degradation in strong alkali, seawater, and thermal exposure up to 200 °C. Mechanistic studies reveal that minimal interlayer expansion reduces electron hopping barriers and interfacial resistance, while π-electron interactions between benzene rings and the Ti–O–P covalent network create electron highways that enhance charge transfer and suppress oxidation. This work provides a rational ligand design principle to optimize MXene stability and conductivity in organic solvents, thereby advancing their applications in energy storage and electronics.