An electro-osmotic flow device featuring electroactive pyrene encapsulated different types of carbon matrices

Host-guest chemistry has gained significant attention in recent years due to its various applications in electrochemical devices. Carbon materials serve as excellent hosts for organic guest molecules. In this study, pyrene molecules were incorporated into five different carbon matrices using a low-temperature thermal encapsulation technique, and the resulting materials were evaluated as effective electrodes for electro-osmotic pump (EOP) application. Since pristine pyrene is electrochemically inactive, it was electrochemically oxidized prior to its use in the EOP. The five carbon materials used in this study, super carbon (SC), multi-walled carbon nanotubes (MWCNTs), Ketjen black carbon (KC), activated carbon (AC) and hard carbon (HC) underwent thorough physicochemical characterization. The encapsulation of pyrene within these carbon matrices, followed by the electrochemical oxidation of the guest pyrene molecules to obtain eSCO, eCNTO, eKCO, eACO, and eHCO, was confirmed through spectroscopic and electrochemical studies. An EOP consists of a silica frit sandwiched between two flow-through electrodes. Five EOPs were assembled with eSCO, eCNTO, eKCO, eACO, and eHCO as the active electrode materials. The water pumping performance of all the EOPs was found to be linearly dependent on the applied voltage. The electro-osmotic flux of the EOPs with eSCO, eCNTO, eKCO, eACO, and eHCO was measured at 33.81, 31.48, 31.18, 20.68, and 7.95 mL min⁻¹ V⁻¹ cm⁻², respectively. The high efficacy of the fabricated EOPs suggests that electroactive pyrene and carbon matrices form a unique host-guest composite material suitable for electrochemical device applications.