A hierarchical vermiculite-CNF/CNT composite nanofluidic membrane for a high-performance moisture-electric generator

It has been observed that the widespread presence of moisture in the atmosphere can store a large amount of latent heat energy. Moisture-electric generators (MEGs) are capable of converting this latent heat into electricity without environmental constraints. However, the key to promoting the large-scale application of MEGs lies in the development of active materials and the optimization of device structure. In this work a new type of MEG was constructed utilizing an ionic hydrogel and vermiculite-cellulose nanofiber/carbon nanotube (VM-CNF/CNT) composite membrane. The specific asymmetric structure enables a dynamic balance between moisture absorption and water evaporation, generating a humidity gradient and an ion concentration gradient within the composite membrane, thereby producing a continuous electric current. At 90% RH, a single device can generate an open-circuit voltage (V_OC) of approximately 0.60 V and a continuous short-circuit current (J_SC) of about 19.6 μA cm⁻². Notably, the device can provide output current to a 1 MΩ load for 150 hours. Through simple parallel configurations, the integrated modules with 15 single MEGs can generate a stable current of 750 μA. This study presents a promising strategy for long-term and sustainable energy harvesting, and its eco-friendly, low-cost design holds great potential for self-powered sensing and wearable electronics.