Ionovoltaic natural evaporation-induced electrical energy harvesting for green hydrogen generation

Electrical energy harvesting via natural water motion along the solid surface has emerged as an advanced renewable energy technology. Amidst the pressing energy demands, natural evaporation-induced electrical energy harvesting has proven its effectiveness in bolstering power generation efficiency through various approaches. Despite such academic endeavors, achieving the practical level of continuous electricity generation remains an ongoing challenge. Herein, an ionovoltaic natural evaporation-induced electrical energy harvesting device utilizing a 2D material-based sodium-doped hydrated vanadium pentoxide film (NaV₂O₅·nH₂O, NaVOH) is demonstrated to facilitate water electrolysis with a high-power output. A unit NaVOH device (1 $\mathrm{cm}$ × 2 $\mathrm{cm}$ × 100 $\mu m$) generates a remarkable continuous open-circuit voltage of ∼1.2 $V$ and a short-circuit current of ∼100 $\mu A$. By arranging multiple devices in series and parallel, voltage and current are successfully amplified to generate green hydrogen, a process demanding substantial power, thereby marking a notable remark in the field of water motion-induced energy harvesting.