Dendritic heterojunction nanowire arrays for high-performance supercapacitors

Abstract

Herein, we designed and synthesized for the first time a series of 3D dendritic heterojunction arrays on Ni foam substrates, with NiCo 2 S 4 nanowires as cores and NiCo 2 O 4, NiO, Co 3 O 4, and MnO 2 nanowires as branches, and studied systematically their electrochemical performance in comparison with their counterparts in core/shell structure. Attributed to the following reasons: (1) both core and branch are pseudocapacitively active materials, (2) the special dendritic structure with considerable inter-nanowire space enables easy access of electrolyte to the core and branch surfaces, and (3) the highly conductive NiCo 2 S 4 nanowire cores provide superhighways for charge transition, NiCo 2 S 4 -cored dendritic heterojunction electrodes synergistically lead to ultrahigh specific capacitance, good rate capability, and excellent cycling life. These results of core/branch dentritic heterojunction arrays is universially superior to their core/shell conterparts, thus this is a significant improvement of overall electrochemical performance.