Effect of Oxygen Substitution in the X Sublattice of Ti ₃ C ₂ T _<i>x</i> MXene on the Performance of Triboelectric Nanogenerators

Two-dimensional (2D) MXenes are shown to substantially enhance the triboelectric properties due to their tunable compositional (M, X, Tx) library, electronic structure, dielectric response, and mechanical robustness. Despite the growing interest in the tunable chemistry of MXenes for energy applications, the effect of oxygen substitution in the carbon sublattice of titanium carbide (Ti3C2Tx) MXene on triboelectric power generation remains largely unexplored. Here, we investigate the effect of oxygen substitution in the X-site of MXenes on the performance of a triboelectric nanogenerator (TENG) device. Our results show that Ti3C2Tx MXene, with no detectable oxygen substitution in the carbon sublattice, explored as a tribopositive electrode material, exhibits improved triboelectric performance as compared to Ti3C2–yOyTx (y = 0.3) MXene when used with a tribonegative polydimethylsiloxane (PDMS) electrode. The maximum current output was observed for the Ti3C2Tx MXene at 1 kΩ, with a current density of 7.31 mA/m2, which is the mean value. Our findings provide fundamental understanding that the absence of oxygen substitution in the carbon sublattice is critical for achieving enhanced triboelectric performance in Ti3C2Tx MXene. This provides important insights into the rational design of 2D MXene-based materials for efficient and sustainable energy-harvesting applications.