Engineering of electrodes with 2D Ti₃C₂T_x-MXene sheets and chloride salt for robust and flexible high electrical power triboelectric nanogenerator

This article focuses on the development of triboelectric nanogenerator (TENG) by utilizing advanced 2D nanomaterials with innovative design and easy fabrication method to achieve durable TENG with high-power density and improved cycling performance. Herein, we fabricated a layer-by-layer stacked vertical contact-separation (CS) mode TENG. In this unique design, we incorporated a thin film of micron-sized Ti₃C₂T_x-MXene ultrathin sheets (TMSs) into a polyethylene terephthalate (PET) based tribo-negative electrode. A tribo-positive layer was prepared by integrating an optimized amount of NaCl into a polyvinyl alcohol (PVA) matrix. After optimization of both triboelectric layers, the optimized TMS-TENG showed an open-circuit voltage (V_oc) ∼ 390 V, short-circuit current (I_sc) ∼ 96 μA, and power density of 6.66 W·m⁻². The boosted performance is due to the synergistic effect of TMSs, used as a charge trapping layer on the electronegative side, and the impact of an NaCl:PVA impregnated layer on the electropositive side of the TENG. The ultrathin-layered structures of sandwiched TMS film serve bifunctionally as a charge accumulation and charge trapping entity simultaneously, increasing the charge separation due to high dielectric constant, and thus increasing the overall output power of the fabricated TENG. The prepared TMS-TENG was tested as a pressure sensor to monitor different sensitive physiological movements of the human body. Further applications of the designed TMS-TENGs have been revealed by powering more than 500 LEDs, an electronic calulator, and swiftly charging micro-capacitors by utilizing direct output power. By engineering electrodes, we can gain insight into the specific role that TMSs play in enhancing the performance of TENGs. This research provides a new avenue for designing self-powered pressure/motion sensors in robotics and harvesting biomechanical energy as electrical energy for sustainable electronics.