LAUSR

Electrohydrodynamic and hydroelectric effects at the water–solid interface are of fundamental importance and also underpin many important applications ranging from the controlled liquid transport by applying an external electric field to the power generation from moving liquid. Also, recent advances in micro/nanofabrication and nanomaterials provide additional dimension and flexibility in controlling electrohydrodynamic and hydroelectric effects at the water–solid interface to achieve preferred functions. Despite extensive progress, the cohesive and unified review of these two largely opposite effects is currently lacking. This review first discusses the important common foundations underpinning these two effects such as contact electrification and electric double layer (EDL), then takes a parallel approach to elaborate the electrohydrodynamic processes such as electrically induced liquid flow, wetting, and droplet motion, as well as the hydroelectricity resulting from their opposite processes. The practical applications and the unsolved challenges related to these two interfacial effects are also highlighted.