Flexible hydrovoltaic generator based on carbon black gradient

The rapid development of the global economy and continuous population growth has intensified energy demand. Traditional hydropower technologies face limitations due to environmental dependency and intermittent operation. To address these issues, a flexible hydrovoltaic generator based on carbon black gradient (CBG-FHEG) was designed, which offers electricity generation across diverse environments. Through systematic investigation, we quantified the effects of temperature/humidity, wind speed, liquid volume, and electrodes on electrical properties. At room temperature, the hydrovoltaic generator obtained an open circuit voltage of approximately 0.12 V using a drop of deionized water (0.2 mL). By connecting the absorbent layer (commercial cellulose paper) to the water source through a cellulose strip, continuous water flow was provided, increasing the generation time from 4000 s to more than 18 h. Additionally, loading CaCl2 on the cellulose paper enabled the generator to output a voltage of 0.3 V, directly absorbing moisture from the air and eliminating dependency on liquid water sources. This device combines carbon black gradients with the hygroscopic materials, breaking through the hydrovoltaic technology's reliance on liquid water sources, achieving adaptive power generation in both dry and humid environments, and providing a new solution for energy supply in wearable devices and remote areas.