Journal
JOURNAL OF POWER SOURCES
Volume 577, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.jpowsour.2023.233239
Keywords
V doping; Electronic structure; Freestanding; Battery-supercapacitor hybrid device; Hydrogen evolution reaction
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In this study, V-doped pyrite NiS2 nanosheets grown on carbon cloth (VNS/CC) were developed as an efficient electrode material for supercapacitors and hydrogen evolution reaction (HER). The VNS/CC electrode exhibited high specific capacity, excellent cycling stability, and superior HER performance. The improved electrochemical performance can be attributed to the doping of V on the NiS2 surface/subsurface and the optimization of water molecule adsorption/dissociation energy.
Rational design of highly active and low-cost electrode material toward energy storage and hydrogen evolution reaction (HER) is promising but still challenging. Herein, we present V-doped pyrite NiS2 nanosheets grown on carbon cloth (VNS/CC) as an efficient electrode material for supercapacitors and HER. The optimal 20% VNS/CC electrode exhibited ultra-high specific capacity (1970 F g 1 at 1 A g 1) with excellent long-term cycling stability (100% retention over 6000 cycles). The 20% VNS/CC//AC battery-supercapacitor hybrid device presented high-energy and high-power performances (e.g., 64.4 W h kg 1 at 799 W kg 1) and excellent cycling stability. Furthermore, the 20% VNS/CC exhibited superior HER performance, including low overpotential and exceptional stability. The combined experiments and density functional theory (DFT) calculations revealed that the superior supercapacitor and HER performance of VNS/CC are attributed to the doping of V on the NiS2 surface/subsurface: (i) significant modulation of the morphology to promote the formation of independent nanosheet structures with abundant active sites and induced pseudocapacitance effects; (ii) practical tuning of the NiS2 electronic structure to convert the semiconductor characteristics into metallic properties with high conductivity, and (iii) optimize the adsorption/dissociation energy of water molecules to enhance the Volmer step reaction rate in alkaline solutions.
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