Dynamic change in the shape of the droplet placed on superhydrophobic Cu-based surface through electrochemical reaction under negative bias potential

Abstract

The interdependence between the redox reactions capable of changing surface composition and the wettability is central to a wide array of applications ranging from electrochemical energy production and storage technologies to wettability control for microfluidic applications. In this study, we have demonstrated that the shape of a potassium chloride-based electrolyte droplet placed on a superhydrophobic copper–copper oxide surface changes dynamically upon the application of negative bias potentials. The copper–copper oxide based superhydrophobic surface with micro-nano structured roughness features was prepared by the electrodeposition process. Studies were conducted at different bias potentials, ranging from −0.6 V to −0.9 V, and the change in the droplet shape based on the contact angle and baseline size is presented. The results show that an increase in the magnitude of the bias potential results in a higher amount of contact angle reduction and baseline size increase over the same duration. The electroreduction of the copper oxide present on the surface is attributed to the change in the droplet shape.