Microwave-assisted synthesis of hybrid Co x Ni1−x (OH)2 nanosheets: Tuning the composition for high performance supercapacitor.

Abstract: Hybrid Co x Ni1−x (OH)2 nanosheets have been successfully synthesized via a facile microwave-assisted synthetic route. The size of Co x Ni1−x (OH)2 nanosheets decreases with the increase of nickel amount; however, the layered crystal structure can be maintained at any ratios of Co:Ni due to the chemical and physical similarities between these two elements. The lattice spacing of the hexagonal nanosheets can be slightly varied by adjusting the ratios of Co:Ni. The hybrid Co0.2Ni0.8(OH)2 hexagonal nanosheets deliver a high capacity of above 1170 F g−1 at a current density of 4 A g−1. The higher specific capacitance of Co0.2Ni0.8(OH)2 nanosheets than their monometallic counterpart could be attributed to the enhancement of the electro-active sites participated in the redox reaction due to the possible valence interchange or charge hopping between Co and Ni cations. These results indicate the importance of layered hydroxide nanosheets with tuned transition-metal composition for high-performance energy storage devices. [Copyright &y& Elsevier]