High evaporation rate and electrical conductivity synergistically boosting porous rGO/CNT Film for water evaporation-driven electricity generation

Harvesting energy from natural water evaporation has attracted tremendous interest recently due to the advantages of independent operation in a wide range of environments and continuous direct current output. However, the currently reported power density is far lower than other renewable energy generation technologies. Herein, we demonstrate that an efficient water evaporation-driven generator (rGO/CNT-EPG) utilizes the synergistic effect of high water evaporation rate and electrical conductivity to achieve a spectacular continuous power output as high as 0.53 W m−2 and a high current density of 267 µA cm−2 under optimal conditions, which is the highest power density among the reported water evaporation-induced generators thus far. Remarkably, even in outdoor environment, the rGO/CNT generator performed a stable power density of 0.6 W m−2 with a high current density of 257.8 µA cm−2 through optical focusing, demonstrating its huge potential for practical applications. This work not only puts deep insights into the effect of electrical conductivity on water evaporation-induced electricity generation but also provides significant guidance to develop high-performance hydrovoltaic devices.