Facile synthesis of mesoporous Ni_0.3Co_2.7O ₄ hierarchical structures for high-performance supercapacitors

In this work, we report the facile synthesis of mesoporous nickel cobalt oxide (Ni_0.3Co_2.7O₄) hierarchical structures with excellent supercapacitive performance. Nickel cobalt oxalate hydrate (Ni_0.1Co_0.9C₂O₄·nH ₂O) is first synthesized as the precursor via a facile precipitation method, followed by controlled annealing to obtain mesoporous Ni _0.3Co_2.7O₄ hierarchical structures. The sample prepared at a relatively low annealing temperature (400 °C) possesses more abundant mesopores and higher specific surface area, and exhibits excellent supercapacitive performance in aqueous alkaline electrolytes. An exceptionally high specific capacitance of 960 and 805 F g^-1 is obtained under current densities of 0.625 and 6.25 A g^-1, respectively, with excellent cyclic stability. The remarkable electrochemical performance is attributed to the desirable composition and the unique hierarchical mesoporous architectures. © 2013 The Royal Society of Chemistry.