An Asymmetric Moisturizing 3D Foam with High Deformability for Complementary Energy Harvesting via Moisture-Induced Electric and Triboelectric Generator

Moisture-induced electric generators (MEGs) have emerged as promising candidates for next-generation energy conversion. However, existing MEG devices face limitations such as low current and voltage outputs, high moisture dependence, and lack of mechanical robustness. In this study, we introduce a novel 3D asymmetric moisturizing deformable MEG device that exhibits exceptional mechanical performance and simultaneously harnesses power from both MEG and triboelectric nanogenerator (TENG) effects. Our device combines an organo-ionic hydrogel infusion within the lower section of a 3D melamine foam substrate, coated with 2D conductive MXene (Ti₃C₂T_x) and hydrophilic poly(vinyl alcohol), resulting in superior water capturing and rapid ion transport capabilities. Notably, this device operates efficiently across a wide range of temperatures (-20 to 60 °C) and relative humidities (20 to 90% RH). Leveraging the negative surface charge of MXene, positive ions from salts and water in the organo-ionic hydrogel are preferentially selected, enabling continuous power generation with a maximum open-circuit voltage and short-circuit current density of 0.32 V and 877 μA cm^-2, respectively. Additionally, the upper layer of our device generates a high voltage (~80 V) through contact electrification with a perfluoroalkoxy alkane film over ~30,000 cycles. The integration of MEG and TENG components yields a high-power output (~83 μW cm^-2), showcasing the device's practical potential for emergency exit sign applications by leveraging the distinctive characteristics of MEG's direct current and TENG's alternating current.