Abstract
Conventional electrochemical devices require two electrodes to maintain charge balance in the electrolyte. Here, we provide experimental evidence of charge accumulation in bulk solution using a single-electrode, high-voltage electrochemical cell. Using Van de Graaff generator (an electrostatic generator) this electrochemical system can produce excess charge in the electrolyte through electrochemical reactions, without violating the global electroneutrality of the electrochemical system, including electrolyte and surrounding environment. This enables a new charge storage concept, liquid phase capacitor, based on spatially separated oppositely charged electrolyte solutions. Furthermore, this approach facilitates the electrosynthesis of platinum nano-catalysts for hydrogen evolution reaction.