High-voltage hydrovoltaic generator based on micro/nano multi-scale superhydrophilic SiO2@activated carbon with enhanced capillary infiltration performance.

Abstract

At least 60 petawatts (10¹⁵ watts) of energy can be absorbed and released annually through the ubiquitous water cycle, but only a fraction of it is exploited. The prospect of harvesting energy from water evaporation and streaming has garnered increasing attention. Nevertheless, there still exist challenges, including insufficient liquid-solid interface contact and inadequate liquid transport. Herein, a synergistic composite material system comprising micron-scale activated carbon and nano-scale silicon dioxide particles via multistep ball milling processes is introduced. The superhydrophilic material combined with a hierarchical structure enhances capillary infiltration performance, thus ensuring continuous liquid flow and sustained transpiration. As a result, the hydrovoltaic generator achieves efficient energy harvesting (an open-circuit voltage of >4.3 V) and environmental monitoring (response to variations in sunlight intensity and wind speed). Notably, the device can maintain high voltage output for over one year, demonstrating its long-term stability. This study can provide guidelines for effectively harnessing sustainable green energy sources in the future.