Porous lanthanum doped NiO microspheres for supercapacitor application

La3+ doped NiO microspheres with porous structure were fabricated using colloidal carbon spheres as hard template via a hydrothermal method followed by calcination process. The morphologies and microstructures of the samples were examined by scanning electron microscopy (SEM), transition electron microscopy (TEM) and X-ray diffraction (XPS). The key point of the successful realization was that the La3+-doped NiO microspheres exhibited smaller feature sizes, high specific surface area (277.5 m(2) g(-1))and large pore volume (0.79 cm(3) g(-1)). Electrochemical properties were characterized by cyclic voltammetry and galvanostatic charge/discharge. The microstructure observations confirmed that La3+ ions were successfully doped into the NiO spheres after heat treatment, and the porous structure was achieved. As a result, 1.5 mol% La3+-doped NiO showed a remarkable specific capacitance of 253 F g(-1) (2 times higher than that of the pure NiO) and good cycling stability (34% capacity increase after 500 cycles). These results demonstrate that La3+-doped NiO composites as electrode materials have potential application for high-performance supercapacitors. (C) 2012 Elsevier B.V. All rights reserved.