Environmental energy harvesting adapting to different weather conditions and self-powered vapor sensor based on humidity-responsive triboelectric nanogenerators.

Triboelectric nanogenerators (TENGs) have been widely applied for energy harvesting and self-powered sensing, while smart deformable materials can be combined with TENG to acquire a more intelligent and self-adaptive system. Here, based on the vapor-driven actuation material of perfluorosulfonic acid ionomer (PFSA), we propose a type of humidity-responsive TENG. The integrated TENG array can automatically bend to the desired angles in responding to different humidity conditions and thus, it can effectively collect energy from both wind and rain drop, where the power density can reach 1.6 W m-2 at wind speed of 25 m s-1 and 230 mW m-2 under rainy condition. Meanwhile, this TENG array can fully lay down in dry weather, using reflective surface to reflect sunlight and heat radiation. The vapor absorption process of PSFA film can also result in the charge accumulation process. Accordingly, relying on the strong absorption capability of PFSA, a TENG-based vapor sensor with high sensitivity has been developed for monitoring chemical vapor leakage and humidity changing. This work opens up a promising approach for the application of the humidity responsive materials in the field of energy harvesting and self-powered sensors. It can also promote the development of TENG toward more intelligent direction.