NiSe2/Ni(OH)2 Heterojunction Composite through Epitaxial-like Strategy as High-Rate Battery-Type Electrode Material

Constructing heterojunction is a promising way to improve the charge transfer efficiency and can thus promote the electrochemical properties. Herein, a facile and effective epitaxial-like growth strategy is applied to NiSe2 nano-octahedra to fabricate the NiSe2-(100)/Ni(OH)(2)-(110) heterojunction. The heterojunction composite and Ni(OH)(2) (performing high electrochemical activity) is ideal high-rate battery-type supercapacitor electrode. The NiSe2/Ni(OH)(2) electrode exhibits a high specific capacity of 909 C g(-1) at 1 A g(-1) and 597 C g(-1) at 20 A g(-1). The assembled asymmetric supercapacitor composed of the NiSe2/Ni(OH)(2) cathode and p-phenylenediamine-functional reduced graphene oxide anode achieves an ultrahigh specific capacity of 303 C g(-1) at 1 A g(-1) and a superior energy density of 76.1 Wh kg(-1) at 906 W kg(-1), as well as an outstanding cycling stability of 82% retention for 8000 cycles at 10 A g(-1). To the best of our knowledge, this is the first example of NiSe2/Ni(OH)(2) heterojunction exhibiting such remarkable supercapacitor performance. This work not only provides a promising candidate for next-generation energy storage device but also offers a possible universal strategy to fabricate metal selenides/metal hydroxides heterojunctions.