Three-Dimensional Polypyrrole Nanoarrays for Wearable Triboelectric Nanogenerators

As an energy-harvesting device, triboelectric nanogenerators (TENGs) have attracted much attention because they can harvest mechanical energy generated from multiple parts of the human body and easily supply energy to wearable devices. Here, we report a lightweight, portable, and wearable TENG device based on three-dimensional polypyrrole nanoarrays (3D PPy NAs), which can both collect mechanical energy and perform self-powered sensing. 3D PPy NAs were fabricated by a facile electrochemical deposition method using carbon paper as the substrate, and different growth morphologies of PPy NAs were obtained by controlling the deposition time. Among them, the PPy NAs with a deposition time of 1000 s had the largest frictional effective area with the pores of poly(vinylidene fluoride) (PVDF), and the constructed PPy-PVDF TENG (2 cm x 2 cm) had the highest output performance, with an open-circuit voltage (V-oc) of 20.2 V and a short-circuit current (I-sc) of 1.3 mu A, which are 2.35 and 2.17 times higher than those of the carbon paper TENG (Cp TENG), respectively. In addition, PPy-PVDF TENG can collect mechanical energy from different parts of the human body such as hands, feet, and armpits and realize human motion pattern monitoring and sensing. The device can light up 21 LEDs with the touch of a hand and successfully drive small electronic devices such as a wearable watch and a portable thermohygrometer by integrating the rectifier circuit with a capacitor. This lightweight and portable PPy-PVDF TENG device demonstrates great potential in the field of wearable devices and self-powered sensing.