Mussel-inspired dopamine-mediated graphene hybrid with silver nanoparticles for high performance electrochemical energy storage electrodes

To facilitate the immobilization of the silver nanoparticles with high crystallinity and stability, the mussel-inspired dopamine is functionalized on the surface of the graphene. Considering the unique adhesive property of a catechol group in the dopamine toward metallic ions, a large amount of silver nanoparticles can be coated on the surface of the dopamine-functionalized graphene. To use the high surface area of graphene, large-sized graphene sheets are prepared using the microwave heat treatment of graphite powder followed by chemical oxidation and exfoliation. In addition, the large-area graphene sheets are selectively collected by a pH-assisted fractionation technique and are confirmed by the green-light filtered optical microscopic images. The dopamine-mediated graphene hybrid with silver nanoparticles shows superior electrochemical activity with enhanced electrical conductivity by promoting the decoration of stable silver nanoparticles on the surface of graphene. The resulting hybrid exhibits 7.6 times and 1.6 times higher electrochemical capacitance than that of the bare and graphene/silver hybrid-modified glassy carbon electrodes, respectively.