MOF-derived 3D hierarchical nanoarrays consisting of NiCoZn-S nanosheets coupled with granular NiCo2S4 nanowires for high-performance hybrid supercapacitors

Abstract

It is an effective strategy to prepare polymetallic multi-dimensional hierarchical nanoarrays to enhance the electrochemical capacity and energy density of supercapacitors. Herein, 3D hierarchical nanoarrays consisting of NiCoZn-S nanosheets coupled with granular NiCo₂S₄ nanowires were fabricated on carbon fibers (CF@NiCoZn-S/NiCo₂S₄). First, using 2D Zn-MOF as a precursor, 3D architecture carbonate hydroxide nanoarrays (CF@NiCoZn-CH/NiCo-CH) were synthesized via a one-step hydrothermal approach in situ. Then, the hierarchical CF@NiCoZn-S/NiCo₂S₄ was fabricated via a simple hydrothermal reaction in a sodium sulfide aqueous solution, and it showed an outstanding capacity of 194 mA h g⁻¹ at 1 A g⁻¹. Significantly, the hybrid supercapacitors (HSCs) assembled with CF@NiCoZn-S/NiCo₂S₄ as the cathode and carbon nanosheets inserted with single-walled carbon nanotubes (CNS–CNTs) as the anode delivered an utmost energy density of 48.7 W h kg⁻¹ at a power density of 800 W kg⁻¹. In addition, this HSC device achieved a capacity retention of 70.1% after 10 000 charge–discharge cycles. Such excellent energy storage characteristics are entirely attributed to the unique structure of the cathode that includes 1D NiCo₂S₄ nanowires with a fast ion/electron transport, 2D NiCoZn-S nanosheets with enhanced structural stability and 3D carbon fiber cloths with excellent mechanical flexibility. Therefore, these 3D architecture electrodes may possess a great potential in energy storage, electrocatalysis or environmental applications.