Investigation of microstructures of ZnCo_2O_4 on bare Ni foam and Ni foam coated with graphene and their supercapacitors performance

The graphene coating was deposited on the surface of Ni foam using the chemical vapor deposition process. A large amount of flower-like ZnCo_2O_4 microspheres with short nanowires were formed on bare Ni foam by hydrothermal method, while large-scale ZnCo_2O_4 nanowires arrays homogeneously aligned and separated adequately on Ni foam coated with graphene. This ZnCo_2O_4 nanowire structure exhibited superior supercapacitors properties. The excellent supercapacitors were mainly attributed to the large specific surface and the porosity on the nanowires which promoted the electrons and ions transportation. In addition, graphene improved conductivity of substrate for current collecting.