High Hydrovoltaic Power Density Achieved by Universal Evaporating Potential Devices

While hydrovoltaic electrical energy generation developments in very recent years have provided an alternative strategy to generate electricity from the direct interaction of materials with water, the two main issues still need to be addressed: achieving satisfactory output power density and understanding the reliable mechanism. In the present work, the integration of capacitors and water evaporation devices is proposed to provide a stable power supply. The feasible device structure consuming only water and air is green and environmentally sustainable, achieving a recorded power density of 142.72 µW cm(−2). The output power of the series of devices is sufficient to drive portable electronic products with different voltage and current requirements, enabling self‐driving systems for portable appliances. It has been shown that the working behavior originates from evaporating potential other than streaming potential. The present work provides both theoretical support and an experimental design for realizing practical application of hydrovoltaic electrical energy generation devices.