Surface termination engineering of 2D titanium carbides for light-activated soft robotics applications

The transition metal carbide (TMC) Ti₃C₂T_x features high conductivity, photothermal conversion, and flexibility, making it promising for light-driven soft actuators. However, conventional synthesis often results in fluorine terminations that degrade photothermal efficiency. This study introduces a plasma-enabled atomic layer etching (plasma-ALE) approach to precisely engineer the surface termination of Ti₃C₂T_x, transforming the surface chemistry from fluorine-dominated to oxygen-dominated terminations, achieving an 80% conductivity increase and significantly enhanced photothermal efficiency. Incorporating cellulose nanofibrils further improves ALE-treated actuator response under near-infrared light, yielding up to 165° bending and 40 mN force, outperforming other 2D material-based actuators. The plasma-ALE process is compatible with various fabrication methods, including vacuum filtration and aerosol jet printing, enabling scalable designs. Furthermore, plasma-ALE treatment facilitates actuators capable of grasping and locomotion. This work paves the way for advanced surface engineering of TMCs and their integration into multifunctional soft robotic systems.