A schematic illustration and overlapped tem images of the formation of CuO 3D nanogrids. (a) PVP nanofibers on the mat deposit on Cu mesh by electrospinning at room temperature; (b) “core-shell” type Cu-PVP nanofiber formation by Cu diffusion and migration through PVP nanofibers (after thermal treatment at C for 2 h (Figure 3)); and (c) Polycrystalline CuO nanowire formed by removal of PVP and oxidation of Cu core (after thermal treatment at C for 2 hrs (Figure 4)).
