Extraction of Evaporation-Driven Electrokinetic Streaming Potential from V2O5 Nanochannels through Secondary Sources

Abstract

The electrokinetic streaming potential derived from the natural evaporation process through nanoscale capillary channels is gaining increasing attention for its potential to be a self-sufficient and maintenance-free energy resource. An evaporation-induced energy-harvesting device displaying energy density up to 40 mWm–2 was fabricated by exploiting atomically thin two-dimensional (2D) nanofluidic channels of a reconstructed V2O5 membrane. Systematic studies were also performed to uncover the effects of internal device parameters, like channel dimensions, membrane thickness, and electrode separation, and external environmental conditions such as relative humidity and atmospheric temperature on energy efficiency. Most importantly, physical damages to the V2O5 device can be healed just by adding a drop of water. The evaporation-induced nanogenerators can be connected to add up the voltage and current values generated by individual devices. Besides, two methods are proposed here to overcome practical hurdles associated with these kinds of devices. In the first method, secondary materials (like cloth and paper) are employed to draw water molecules from the reservoir and transfer it to surface-active nanofluidic channels. In the second method, a hydrophilic gel membrane of agar, LiCl, and glycerol is used to mimic the natural hydrological cycle for continuous power output even in low humid conditions.