Synergistic photo-electro-piezo effects in a polypyrrole/MnO2-PVDF nanofiber membrane for higher energy efficiency of hybrid solar evaporation systems

Energy harvesting technologies are gaining attention because of their potential to generate power from ambient sources like light and mechanical motion. The development of advanced electrospun polyvinylidene fluoride (PVDF) flexible films with dual functionality (photothermal-piezoelectric effect) has become a prominent area of research, focusing on optimizing their hydrophilicity. Herein, electrospun MnO 2 nanosheets/PVDF flexible films are sequentially fabricated to transform the dielectric and ferroelectric properties, which result in an open-circuit voltage of 20 V and a short-circuit current of 0.10 μA under repeated mechanical force of 10 N at 2 Hz. Wearable films demonstrated the ability to harvest the biomechanical energy of human movements, such as finger and joint tapping, as well as wearable shoe soles that harvest energy from walking and running. More importantly, the impregnation of polypyrrole over MnO 2 /PVDF films (MnPVDF@PPy) and post-hydrophilic modification achieved an enhanced evaporation rate of 1.85 kg m −2 h −1 and waste heat recovery into open-circuit voltage of 135 mV and a short-circuit current of 33 mA under one sun irradiation. The unique interplay between photo-piezo-electro mechanisms ensures efficient energy flow, robustness, and adaptability in dynamic environments by addressing critical challenges such as water scarcity and intelligent sensing with a single, multifunctional platform.