Novel Ni₃S₄/NiS/NC composite with multiple heterojunctions synthesized through space-confined effect for high-performance supercapacitors

Abstract

The construction of heterojunctions in composite materials to optimize the electronic structures and active sites of energy materials is considered to be the promising strategy for the fabrication of high performance electrochemical energy devices. In this paper, a one-step, easy processing and cost-effective techniques for generating heterojunctions of the composite materials are successfully developed. The composite containing Ni3S4, NiS, and N-doped amorphous carbon (abbreviated as Ni3S4/NiS/NC) with multiple heterojunction nanosheets are synthesized via the space-confined effect of molten salt interface of recrystallized NaCl. Several lattice matching forms of Ni3S4 with cubic structure and NiS with hexagonal structure are confirmed by the detailed characterization of heterogeneous interfaces. The C-S bonds are the key factor in realizing the chemical coupling between nickel sulfide and NC and constructing the stable heterojunction. DFT calculations further reveals that the electronic interaction on the heterogeneous interface of Ni3S4/NiS can contribute to high electronic conductivity. The heterogeneous interfaces are identified to be the good electroactive region with excellent electrochemical performance. The synergistic effect of abundant active sites, the enhanced kinetic process and valid interface charge transfer channels of Ni3S4/NiS/NC multiple heterojunction can guarantee high reversible redox activity and high structural stability, resulting in both high specific capacitance and energy/power densities when it is used as the electrode for supercapacitor. This work offers a new avenue for the rational design of the heterojunction materials with improved electrochemical performance through space-confined effect of NaCl.

Innovative solvent-free compound-direct synthesis of defect-rich ultra-thin NiS nanosheets for high-performance supercapacitors

“…That is to say, there are two pairs of redox peaks, which in turn correspond to the reversible redox reaction between Ni 2+ and Ni 3+ , and Ni 3+ and Ni 4+ . 23,24 With the increase of the scan rates, the concentration polarization and electrochemical polarization gradually shift the position of the redox peaks to both ends (Fig. 4a).…”

Three-dimensional biotemplate-loaded nickel sulfide vacancies engineered to promote the absorption of electromagnetic waves

“…4c, the Ni 2p spectrum consists of two pairs of satellite peaks at 860.0 and 877.0 eV and 862.8 and 879.9 eV and two pairs of spin–orbit doublet peaks corresponding to Ni 2p 3/2 and Ni 2p 1/2 of Ni 2+ (852.1 and 869.4 eV) and Ni 3+ (855.6 and 873.4 eV) Ni 2+ and Ni 3+ , respectively, distributed in Ni 3 S 4 and Ni x S 6 . 38,39 In Fig. 4d, the S 2p spectrum was analyzed, revealing four distinct peaks, with the peaks located at 160.0 and 161.1 eV corresponding to S 2p 3/2 and S 2p 1/2 of S 2− , respectively, and the other two peaks at 162.2 and 167.7 eV are associated with the presence of S–C bonds and the oxidation of Ni 3 S 4 and Ni x S 6 , 40 respectively.…”

Construction and application of NiCo2O4@MnS composite with hierarchical structure for hybrid supercapacitor

“…Furthermore, the electrochemical characteristics of composite materials are usually superior to those of single materials. 25 Meanwhile, the composite materials can use the benefits of two materials and intentionally combine them into a hierarchical structure to compensate for drawbacks in single structures. 26 Some published works have indicated that the electrochemical performances of metal oxides, sulfides and hydroxides (NiCo 2 O 4 @Ni(OH) 2 , 27 MnCo 2 O 4 @Ni 3 S 2 , 28 NiCo 2 O 4 @NiCo 2 S 4 , 29 NiCo 2 O 4 @Ni–S, 30 or NiCo 2 O 4 @NiCo-LDH 31 ) are better than those of single metal oxides.…”