Voltage Distribution in Porous Carbon Black Films Induced by Water Evaporation

Water-evaporation-induced (WEI) electricity generation has been widely studied, but the explanation for the working mechanism remains controversial yet. In this study, porous carbon black (CB) films with multiple parallel electrodes were prepared and the voltage distribution in these films was investigated during WEI electricity generation. We found that in both toluene and ethanol CB films, voltage between neighboring electrodes increases first but then decreases with increasing height above the bulk water surface. This voltage distribution derives from similar volumetric flow rate distribution of water inside the film, which is caused by the hydrophilicity of film and water evaporation. Our results support streaming potential and present more details during WEI electricity generation. It is helpful for understanding the mechanism in other material systems as well.