Surface Charge Dependence of the Direct Piezoelectric Response of a Room Temperature Ionic Liquid: Implications for Nanoscale Control over Sensing and Actuation

We report on the surface charge-dependence of the direct piezoelectric response of a room temperature ionic liquid (RTIL). Surface charge is controlled chemically by the surface-modification of ITO-coated glass supports with a nanometer thick monolayer of graphene oxide phosphate (P-GO), which carries a net negative charge when phosphate terminated and a net positive charge upon reaction with Zr4+. The dependence of the RTIL direct piezoelectric response on the surface charge correlates with the ability to modulate the surface-induced charge density gradient seen in RTILs, establishing an empirical connection between the direct and converse piezoelectric responses in RTILs.