Heterostructured Ni2P/NiMo-layered double hydroxide nanoarrays with enriched redox active sites for supercapacitors

Abstract

The electroactivity and cyclic stability of transition metal phosphides (TMPs) for supercapacitors are restricted by inadequate redox active sites and huge volume changes during the charging/discharging process. Herein, a three-dimensional (3D) porous Ni2P/NiMo-layered double hydroxide (NiMo-LDH) heterostructure with large specific surface and abundant pore channels is explored as a self-supporting supercapacitor electrode. The well-defined hierarchical pore structure can offer numerous electroactive sites and short ion/electron pathways. The generation of heterointerfaces between multi-dimensional Ni2P and two-dimensional (2D) NiMo-LDH nanosheets endows the hybrid composite with improved electrical conductivity and structural robustness. Consequently, the special nanoarchitecture design achieves a specific capacity of 198.6 mAh g−1 (2.28 mAh cm−2) at 1 A g−1 and an impressive rate performance of 78.3% at 20 A g−1. More importantly, the assembled Ni2P/NiMo-LDH//orange peel-derived porous carbon (OPC) asymmetric supercapacitor (ASC) device delivers a remarkable specific energy of 63.7 Wh kg−1 at a specific power of 1138.3 W kg−1 and long-term cycling stability (91.7% over 10,000 cycles). The research highlights that the hybridization of TMPs and other nanostructured battery-type materials may produce a synergistic effect and boost the capacitive properties.