Ambient-Dried Nanocellulose Composite Aerogels for Enhanced Hydrovoltaic Electricity Generation

Hydrovoltaic electricity generators (HEGs), which can harvest clean energy from the ubiquitous evaporation of water, have recently attracted significant interest. The utilization of renewable porous aerogels in the development of HEGs can enhance their sustainability and performance. Herein, an efficient HEG based on ambient-dried composite aerogels (ADAs) composed of nanocellulose and carbon nanotubes (CNTs) is presented. The abundant carboxyl groups on the nanocellulose and CNTs enable electrostatic complexation with metal ions. This not only stabilizes the engineered porous ADA architecture during both ambient drying and operation but also enhances spontaneous and continuous electricity generation by boosting interactions with water molecules. The prepared HEG demonstrates an outstanding output voltage of 697 mV and a high power density of 0.57 µW cm⁻² for long-term operation in water. Furthermore, the HEG exhibits significantly improved performance when operating in brine, achieving an output voltage of 850 mV and a power density of 3.82 µW cm⁻². This research demonstrates that large-scale integrated HEGs units can provide customized electricity output to power various electronics and efficiently detect water leaks through human–machine interactions. This study provides a reliable and efficient strategy for fabricating efficient nanocellulose HEGs and paves the way for self-powered water sensing.