Influence of MXene Composition on Triboelectricity of MXene-Alginate Nanocomposites.

MXenes are highly versatile and conductive 2D materials that can significantly enhance the triboelectric properties of polymer nanocomposites. Despite the growing interest in the tunable chemistry of MXenes for energy applications, the effect of their chemical composition on triboelectric power generation has yet to be thoroughly studied. Here, we investigate the impact of the chemical composition of MXenes, specifically the TiCNT carbonitride vs the most studied carbide, TiCT, on their interactions with sodium alginate biopolymer and, ultimately, the performance of a triboelectric nanogenerator (TENG) device. Our results show that adding 2 wt % of TiCNT to alginate produces a synergistic effect that generates a higher triboelectric output than the TiCT system. Spectroscopic analyses suggest that a higher oxygen and fluorine content on the surface of TiCNT enhances hydrogen bonding with the alginate matrix, thereby increasing the surface charge density of the alginate oxygen atoms. This was further supported by Kelvin probe force microscopy, which revealed a more negative surface potential on TiCNT-alginate, facilitating high charge transfer between the TENG electrodes. The optimized TiCNT-alginate nanogenerator delivered an output of 670 V, 15 μA, and 0.28 W/m. Additionally, we demonstrate that plasma oxidation of the MXene surface further enhances triboelectric performance. Due to the diverse surface terminations of MXene, we show that TiCNT-alginate can function as either tribopositive or tribonegative material, depending on the counter-contacting material. Our findings provide a deeper understanding of how MXene composition affects their interaction with biopolymers and resulting tunable triboelectrification behavior. This opens up new avenues for developing flexible and efficient MXene-based TENG devices.