Single electrode piezoelectric nanogenerator for intelligent passive daytime radiative cooling

Passive daytime radiative cooling (PDRC) can cool down objects by simultaneously reflecting sunlight and radiating heat to the cold external space, which has no energy consumption. Traditional PDRC design usually needs to rely on micro-nano structures, which are easily damaged and lose function. On the one hand, the mechanical strength of PDRC can be enhanced. On the other hand, by integrating self-monitoring character in the same membrane fault part can be easily distinguished for fixing or replacing. Monitoring the damage by using traditional sensors will cause additional energy loss. Therefore, an intelligent PDRC that can monitor the failure itself is urgently needed to be developed. Here we found that the polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) nanofiber membrane obtained by electrospinning technology can effectively scatter sunlight, while emitting infrared rays matching the atmospheric window to achieve effective heat dissipation. In the preparation process, the electrostatic field can effectively polarize the PVDF-HFP to obtain good piezoelectric performance, which can be used to monitoring the integrity of membrane function. Meanwhile, the membrane can be used as a nanogenerator to collect mechanical energy in the environment, such as raindrop energy when used on the roof, thereby not only reducing cooling energy loss, but also collecting energy additionally, achieving a dual energy-saving design. Its excellent self-cleaning and recyclable characteristic bring more benefits to its green and energy-saving features. Therefore, this intelligent PDRC provides ideas for new energy-saving designs. At the same time, a simple preparation method is more conducive to the promotion of this technology.