Unveiling the Critical Role of Surface Oxidation of Electroresponsive Behaviors in Two-Dimensional Ti ₃ C ₂ T _x MXenes

Here, two-dimensional (2D) C/TiO ₂ hybrids synthesized via oxidation of Ti ₃ C ₂ T _x MXenes are reported as an ideal electrorheological (ER) candidate in pursuit of high ER efficiency. The lamellar structure of conductive carbon layers provides abundant electron transport channels, aiming to shorten the response time to an electric field, while the TiO ₂ nanoparticles deliver high surface polarization leading to high ER effects. The oxidation degrees of Ti ₃ C ₂ T _x MXenes are systematically controlled through the hydrothermal method (h-C/TiO ₂ ) or CO ₂ calcination (c-C/TiO ₂ ). We comprehensively studied the relationship between the surface oxidation and ER behaviors of these C/TiO ₂ hybrids. It was found that the h-C/TiO ₂ hybrid exhibited superior ER behaviors compared with the c-C/TiO ₂ hybrid. The holey h-C/TiO ₂ architecture creates large electron and oil transport pathways, which is responsible for the superior ER performances. Overall, this research provides original insights into the exciting electroresponsive materials of this quickly growing 2D MXene family as well as provides a guideline for processing oxidation of MXenes for diverse applications.