Direct Measurement of the Differential Capacitance of Deep Eutectic Solvents on Platinum and Glassy Carbon Electrodes.

Differential capacitance is a crucial parameter that connects the experimental observation of electrical double-layer behavior with theoretical models. However, the current number of reported differential capacitance values for deep eutectic solvents remains limited, making it challenging to verify or refute existing models. In this study, we systematically investigate the differential capacitance in deep eutectic solvents using chronoamperometry. By comparing metal and glassy carbon electrodes across various liquid combinations and ion concentrations, we observed a range of distinct capacitance characteristics. While some findings align with the existing mean-field model for ionic liquids, others clearly reflect the influence of electrode materials, with certain cases resisting full explanation by current theoretical models. These results underscore the importance of selecting appropriate electrode materials in experimental studies of such electrolytes and highlight the need for further theoretical advancements in understanding this complex liquid system.