Achieving 100% Utilization of Reduced Graphene Oxide by Layer-by-Layer Assembly: Insight into the Capacitance of Chemically Derived Graphene in a Monolayer State

Face-to-face restacking is one of the main reasons for low surface utilization of multilayered graphene. In this study, multilayered reduced graphene oxide/polymer architecture was fabricated by gas phase or chemical reduction of thin films composed of graphene oxide monolayers using poly­(diallyldimethylammonium) as the cationic binder deposited by layer-by-layer self-assembly. The electrochemical behavior of the thin films in acidic and neutral electrolytes was investigated by using cyclic voltammetry and electrochemical impedance spectroscopy. A transmission line model was adopted to simulate the electrochemical impedance data. The electrochemical data were analyzed and deconvoluted into charge storage due to non-Faradaic electrical double layer capacitance and pseudocapacitance arising from Faradaic surface redox reactions. Pseudocapacitance observed in acidic electrolyte is proportional to the amount of surface functional groups. An overall volumetric capacitance as high as 364 F cm<sup>–3</sup> was achieved for the nanoarchitecture, and it is shown that the electrical double layer capacitance of a monolayer of graphene oxide is 20 μF cm<sup>–2</sup>, regardless of the number of layers deposited. This can be interpreted as full capacitive utilization of reduced graphene oxide sheets in the multilayered reduced graphene oxide films.