Investigation of carrier density modulation in water motion-induced ionovoltaic electricity generation

The solid-liquid interfacial effect plays a pivotal role in electricity generation from the interaction between a solid surface and dynamic water motion, but demonstration of the exact source in energy conversion is deficient and understandings of fluidic processes with water and corresponding charge carrier movement have been non-straightforward to date. Herein, the mechanism of water motion-induced energy generation at 2D nanomaterials is demonstrated by water contact-driven carrier density modulation and regarding fermi energy level shift. When water infiltrates into a nanoporous graphitic channel, a non-linear current density (J)-voltage (V) characteristic is found between wet-dry regions which provides a clue that water interaction repels its major carriers (p-type, holes), thereby motivating electron-rich state on the wet region. This unique characteristic yields the potential asymmetry and hence, drives respective majority charge carriers from wet and dry regions simultaneously to the external circuit. Such dynamic carrier motions are also supported by metal electrode configuration, which relies on the energy state of each region. By observing that the desired configuration brings about a synergic impact on output performance, the source of electricity generation is identified by proving modulated electronic energy levels between wet and dry regions.