Enhanced Energy Harvesting Performance of Triboelectric Nanogenerator via Efficient Dielectric Modulation Dominated by Interfacial Interaction

Abstract A long-standing hurdle in triboelectric nanogenerator (TENG) is to boost the output performances, which is a prerequisite for practical applications in portable or distributed power sources. Dielectric modulation of the triboelectric materials has proved as an efficient strategy to tackle this challenge by optimizing their charge trapping capacity and surface charge density. Herein, we introduce two kinds of typical two-dimensional transition metal carbide (Ti3C2Tx) and carbonitride (Ti3CNTx) MXene into poly(vinylidene difluoride) (PVDF) ferroelectric polymers to achieve efficient dielectric modulation. Surprisingly, the nitrogen atoms partially and randomly substituting carbon atoms in Ti3C2Tx endow Ti3CNTx with more abundant surface terminating groups (–OH and –F) and additional –NH groups, providing strong interfacial interactions, enhanced compatibility with PVDF matrix and dielectric polarization locking. These unique characteristics enable efficient dielectric modulation of PVDF/Ti3C2Tx and PVDF/Ti3CNTx films, significantly enhancing their charge trapping capacity and surface charge density. The optimized TENG device based on PVDF/Ti3CNTx exhibits higher maximum instantaneous power density of 2.5 W/m2 than the devices based on PVDF/Ti3C2Tx (1.6 W/m2) and pristine PVDF (0.4 W/m2). This finding provides guidance for designing advanced triboelectric materials but also call for more exploration for fundamental mechanisms behind dielectric modulation.