Surface Engineering of Graphene Oxide Shells Using Lamellar LDH Nanostructures.

The discovery of graphene oxide (GO) has made a profound impact on varied areas of research due to its excellent physicochemical properties. However, surface engineering of these nanostructures holds the key to enhanced surface properties. Here, we introduce surface engineering of reduced GO (rGO) shells by radially grafting Ni-Co layered double hydroxide (LDH) lamella on rGO shells to form Ni-Co LDH@rGO. The morphology of synthesized Ni-Co LDH@rGO mimics dendritic cell-like three-dimensional (3D) hierarchical morphologies. Silica nanospheres form self-sacrificial templates during the reduction of GO shells to form rGO shells during the template-assisted synthesis. The radial growth of LDH lamellae during hydrothermal process on GO shells provides access to a significantly larger number of additional active redox sites and overcompensates the loss of pseudocapacitive charge storage centers during the reduction of GO to form rGO shells. This enables in the synthesis of novel surface-engineered rGO nanoshells, which provide large surface area, enhanced redox sites, high porosity, and easy transport of ions. These synthesized 3D dendritic cell-like morphologies of Ni-Co LDH@rGO show a high capacitance of ∼2640 F g. A flexible hybrid device fabricated using this nanomaterial shows a high energy density of ∼35 Wh kg and a power density of 750 W kg at 1 A g. No appreciable compromise in device performance is observed under bending conditions. This synthesis strategy may be used in the development of functional materials useful for potential applications, including sensors, catalysts, and energy storage.