<i>In Situ</i> Transformation of Metal Molybdates into Polymetallic Sulfides with Enriched Edge Sites for High-Performance Supercapacitors
Kai Zhang, Hong‐Yan Zeng, Kaiwen Ge, Mingxin Wang, Hao‐Bo Li
Abstract
An effective approach to synthesize polycrystalline Ni–Co–Mo sulfide (NiCoMoS) is developed through doping engineering coupled with chemical transformation. The polycrystalline NiCoMoS with enriched active edge sites is designed and fabricated on a Ni foam (NF) via a facile hydrothermal calcination and post-sulfidation approach, where the polycrystalline NiCoMoO 4 precursor is elaborately prepared by doping Co ions into the NiMoO 4 lattice and subsequently in-situ -converted into NiCoMoS with 3D architectures of ordered nanoneedle arrays. Benefiting from the unique 3D structure and synergistic effects of each component, the optimized needle-like NiCoMoS (2.0) arraying on a NF as a self-standing electrode exhibits superior electrochemical performances with a high specific charge (920.0 C g –1 at 1.0 A g –1 ), excellent rate capability, and good long-term stability. Furthermore, the assembled NiCoMoS//activated carbon hybrid device presents a satisfactory supercapacitor performance, affording an energy density of 35.2 W h kg –1 at a power density of 800.0 W kg –1 and competitive long-term stability (83.8% retention at 15 A g –1 after 10,000 cycles). Such a novel strategy may pave a new route for exploring other polymetallic sulfides with enriched, exposed active edge sites for energy-related applications.