Direct Current Electricity Generation from Dynamic Polarized Water–Semiconductor Interface

Abstract

Interpreting the nature of water molecules and generating electricity from water have been important topics both in science and in society. Recently, there is a rising interest for converting the kinetic energy of a water droplet into electricity, especially direct current (DC) electricity, which can directly power electronic sensors and chips. However, the existing electricity generation techniques are dependent on the moving direction of water, which prevents the output of due DC electricity but generates undesired alternating current electricity. Here, we report DC electricity generation from the dynamic polarized water–semiconductor interface by moving a water droplet in an arbitrary direction within a sandwiched graphene–water–semiconductor structure. The direction-independent DC electricity generation is based on a nontrivial mechanism, in which the water molecules experience polarization and depolarization processes, resulting in electricity output at the water–semiconductor interface during the motion of the water droplet. The open-circuit voltage is tunable by the Fermi level difference between two plates that contain the water droplets, where graphene–water–silicon and aluminum–water–silicon show DC voltages of ∼0.3 and ∼1.0 V, respectively. Our results reveal the phenomenon at the water–semiconductor interface and provide a new route to generate DC electricity by water for potential sustainable, encapsulated self-powered devices.