Evaporating hydrovoltaics with asymmetric electrodes

Abstract

Power generation through natural evaporation shows great potential for green energy technologies. However, it remains a great challenge to balance the coupling effect between the interfacial potential and streaming potential. Here, we propose a new evaporating-hydrovoltaic strategy with asymmetric electrodes to optimize the coupling effect. This device uses active electrode to enhance interfacial interactions while inert electrode to avoid mutual blocking of interfacial potentials. The polytetrafluoroethylene (PTFE) membrane acts as a conductive connection path and induces a streaming potential. It is found that configuration of C (inert electrode)- PTFE (positively charged porous material)-Cu (active electrode) along the water gradient, achieves the optimal power generation. Exposing such a centimeter-sized device to environmental condition can generate ∼0.36 V voltage and lasts for ∼10 h without significant changes. Such high performance is ascribed to the consistency of potential level between interfacial potential and streaming potential. The findings provide a general guideline for sustainable power generation based on a synergistic effect of interfacial potential and streaming potential, which has far-reaching implications to the future design of hydrovoltaics.