Chemically modified MXene nanoflakes for enhancing the output performance of triboelectric nanogenerators

Composite materials composed of a matrix polymer and nanomaterial filler have been actively investigated for the fabrication of triboelectric friction layers using bulk composite solution. The key to enhancing the performance of triboelectric generators (TENGs) using this approach is to incorporate an appropriate filler in the matrix polymer. To date, various fillers have been used to form polymer composites for TENGs. However, only limited attempts have been made to chemically modify the electrical polarity of the filler. Herein, we present a new approach of compositing ferroelectric polymers with chemically modified Ti3C2 fillers to boost the output performance of TENGs. Negatively modified N-functionalized Ti3C2 (N-Ti3C2) was composited with PVDF-TrFE used as a negative triboelectric friction layer, and positively modified NH2-functionalized Ti3C2 (NH2-Ti3C2) was composited with Nylon 11 to form a positive triboelectric friction layer. Through composite formation, the surface potential of each friction layer was increased in the desired (positive or negative) direction, and it was further boosted by electrical polarization in the preferred direction. Consequently, the TENGs fabricated using PVDF-TrFE/N-Ti3C2 and Nylon 11/NH2-Ti3C2 demonstrated a peak output open-circuit voltage of 250 V, short-circuit current density of 280 µA/cm2, and charge density of 210 µC/m2, and delivered an output power density of 13 mW/cm2. In addition, the mechanical strength of the polymer matrix was enhanced owing to composite formation. The composite friction layers fabricated using chemically polar-modulated MXene presented in this work provides a facile way to fabricate high performance TENGs.