NiSe(2)/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 NiSe(2) nano-octahedra to fabricate the NiSe(2)-(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 NiSe(2)/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 NiSe(2)/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 NiSe(2)/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. [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s40820-020-0392-8) contains supplementary material, which is available to authorized users.