Boosting triboelectric charge generation using high-performance functional MAX phase nanofillers incorporated in silicone elastomers

Abstract

Triboelectric nanogenerators (TENGs) have emerged as an effective approach for harvesting low-frequency mechanical energy for self-powered wearable electronics and human–machine interface applications. Polydimethylsiloxane (PDMS), a widely used tribonegative elastomer, offers excellent flexibility and charge retention; however, its inherently low dielectric constant and limited charge transport capability restrict the attainable power density. In this work, a MAX-phase-enabled strategy is introduced by incorporating layered Ti₃AlC₂ as a functional filler within the PDMS matrix to overcome these intrinsic limitations and enable synergistic charge generation and transport. Unlike conventional carbon- or ceramic-based fillers, the MAX phase uniquely integrates metallic conductivity, ceramic-like mechanical robustness, and a two-dimensional layered structure with tunable surface chemistry. This hybrid architecture provides abundant interfacial polarization sites, efficient charge trapping centres, and accelerated carrier migration pathways, while retaining mechanical durability under repeated contact–separation cycles. Systematic compositional optimization reveals that a 10 wt% Ti₃AlC₂ loading maximizes the dielectric constant, electrical conductivity, and surface charge density without inducing percolation-driven performance degradation observed at higher filler concentrations. Kelvin probe force microscopy (KPFM) directly probes nanoscale charge dynamics, revealing faster charge redistribution and suppressed localized charge accumulation in the PDMS-MAX composite compared to pristine PDMS, thereby validating the proposed charge diffusion and migration mechanism. Consequently, the optimized TENG delivers an output voltage of 230 V, a short-circuit current of 28.5 µA, and a peak power density of 20.5 W m⁻² from a compact 20 mm × 20 mm device under an input force of 10 N at 2.5 Hz. Finite Element Analyses (FEA) further corroborate the enhanced electric field and surface charge density. The device exhibits excellent durability over 15 000 cycles, stable operation under varying humidity and aging conditions, and effective performance in capacitor charging, LED illumination, and real-time human motion sensing. This study establishes MAX-phase-filled elastomers as a robust and mechanistically distinct platform for high-performance triboelectric energy harvesting beyond conventional filler-based enhancements.