Highly Flexible Hybrid Self‐Poled Piezoelectric‐Pyroelectric Hybrid Ti ₃ C ₂ T _x

In this paper, we report a high‐performance flexible hybrid piezoelectric‐pyroelectric nanogenerator based on highly crystalline multi‐layered titanium carbide (Ti ₃ C ₂ T _x ) nanosheets (MXene) under a polyvinylidene fluoride (PVDF) matrix to simultaneously harvest mechanical and thermal energies for the first time. HR‐TEM reveals the formation of the layered structure of crystalline Ti ₃ C ₂ T _x with a nanosheets‐like morphology, with an average thickness of 4–6 nm. Very high piezoelectric β‐phase of 69.6% PVDF is achieved through self‐poling of Ti ₃ C ₂ T _x nanosheet with 20% filler concentration. Flexible Ti ₃ C ₂ T _x nanosheet‐PVDF piezoelectric nanogenerators produce a very high output voltage of 22 V and current density of 206 nA/cm ² even under a small compressive force of 0.5 kgf, even without electrical poling. The pyroelectric nanogenerator showed an output voltage of 5.6 V under thermal heating and cooling conditions. The output voltage was increased to 12.06 V under heating and pressure conditions, showing excellent capabilities to harvest both mechanical and thermal energy. Surprisingly, a record‐high output voltage of about 150 V was obtained from piezoelectric nanogenerator under 10 kgf of pressure. The flexible nanocomposite exhibited a high dielectric constant of about 47.18 at low frequency.