Graphene-based composites are promising materials for supercapacitors due to the high specific surface area and electrical conductivity of graphene. Reduction of graphene oxide (GO) is a practical approach to obtain graphene-like material but it suffers from the re-stacking of the graphene sheets. Herein, a two-dimensional composite electrode based on electrochemically reduced GO (ERGO) and polydopamine (PDA) is reported where the PDA is used as a "bioinspired chemical insert" to tackle with the restacking issue of graphene layers. This green and facile electrochemical fabrication method starts from the electro-reduction of GO followed by the electro-oxidation of dopamine (DA), present in the same electrolyte, by a simple switch between a cathodic to an anodic potential. The optimized ERGO-PDA composite electrode possesses combined features of excellent capacitive behavior, with a relaxation time (0) of 0.88 s, high gravimetric and volumetric capacitances (178 F•g -1 and 297 F•cm -3 , respectively, at 10 mV•s -1 ) and finally an excellent cycling stability at 100 to 2000 mV•s -1 , at least for 30000 cycles. DA electropolymerization yield monitored by quartz crystal microbalance and X-ray diffraction measurements demonstrate that PDA is formed between the graphene sheets which prevents the sheets from restacking and facilitate species diffusion inside the composite leading to a volumetric energy density of 8.6 mWh•cm -3 for a power density of 7.8 W•cm -3 . Additionally, the electrochemical quartz crystal microbalance demonstrates a dominant cationic charge compensation and a very efficient interfacial transfer characteristics since a totally reversible mass response during charge/discharge was observed for the optimized ERGO-PDA electrode.
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