One-step synthesis of MnS/MoS₂/C through the calcination and sulfurization of a bi-metal–organic framework for a high-performance supercapacitor and its photocurrent investigation

Abstract

Based on a Mn/Mo-metal organic framework (MOF) precursor, [Mn(4,4'-bipyridine)0.5 MoO4]·1.5H2O, a MnS/MoS2/C hybrid was synthesized through a calcination and sulfurization approach and it is mainly constituted by MoS2/C nanorods and MnS/MoS2/C nanoflakes. The MnS/MoS2/C hybrid delivers a high specific capacitance of 1162 F g-1 at 0.5 A g-1 in 2 M KOH electrolyte, and it possesses a good rate capacity with a retention of 75.7% (880 F g-1) at 10 A g-1, which is due to the synergetic effects of the components MnS, MoS2 and carbon matrix in the hybrid material. The carbon matrix in the hybrid material can not only anchor the active components of MnS and MoS2, but also transport electrons efficiently. The completely exposed Mo and S edges on the preferential 2H-(002) and 3R-(003) facets of MoS2 are beneficial for ion adsorption and electrochemical reaction. An asymmetric supercapacitor constructed by the MnS/MoS2/C hybrid (positive electrode) and activated carbon (AC) (negative electrode) exhibited a capacitance retention of 81% after 5000 galvanostatic charge-discharge cycles (GCD). During the GCD process, the metal sulfides were probably transformed into metal hydroxides in the presence of OH- electrolyte ions. In addition, the MnS/MoS2/C hybrid exhibits a visible light-driven photocurrent response, and DFT calculation proves that it is attributed to the semiconducting feature of MoS2 in the hybrid.

Metal–Organic Framework Derived Bimetallic Materials for Electrochemical Energy Storage

“…In a further increase of complexity in MOF transformations, a hybrid MnS/MoS 2 /C composite was prepared by carbonization of a Mn/Mo‐MOF precursor and subsequent sulfurization (Figure 14 a). [57] In this example, the carbon matrix again served as the support for the small MnS and MoS 2 NPs of the composite, resulting in the increased electrical conductivity and electron transfer rate of the composite. Moreover, a synergistic effect between the MnS and MoS 2 components was also found.…”

“…After 10 000 cycles, the specific capacitance and Coulombic efficiency (≈100 %) of the MnS/MoS 2 /C composite was outstandingly retained (Figure 14 b). The main reason for this remarkable stability was proposed to be the adequate rate of electrolyte ion distribution and their electrochemical interaction with the active NPs at the electrode interface over the charge–discharge cycle [57] …”

N‐doped Carbon‐coated Metal Sulfides/Phosphides Derived from Protic Salts for Oxygen Evolution Reaction

“…The high-resolution Mo 3d spectrum reveals two oxidation states for Mo, corresponding to Mo 4 + (229.5 and 232.6 eV) and Mo 6 + (235.6 eV), respectively, indicating the successful formation of MoS 2 . Mo 6 + can be attributed to partial oxidation of Mo 4 + species, [36,37] and the peak located at 226.6 eV belongs to S 2 s. The generation of MoS 2 was also confirmed in the S 2p spectrum, which exhibits peaks at 162.1 eV for S 2p 3/2 and 163.2 eV for S 2p 1/2 , the characteristic peaks for sulfide species. The shakeup type peak of S is shown at 168.8 eV, which can be ascribed to surface oxidation of S 2À to S 4 + , [38,39] The high-resolution Ni 2p spectrum shows two peaks at 873.5 and 855.9 eV, corresponding to Ni [40,41] In addition, the N 1s spectrum ( Figure 3D) demonstrates the existence of pyridinic-N (398.1 eV), pyrrolic-N (399.3 eV) and quaternary-N (401.5 eV), clearly confirming the formation of N-doped carbon shell.…”

Porous Carbon-Based Supercapacitors Directly Derived from Metal–Organic Frameworks

“…A novel composite of MnS/MoS 2 /C was prepared from the Mn/Mo-MOF self-sacrificing precursor, [Mn(4,4′-bpy)0.5∙MoO 4 ]∙1.5H 2 O, and sulfur powder by simultaneous thermal process of calcination and sulfurization [ 201 ]. The precursor was synthesized from MnSO 4 ∙4H 2 O, Na 2 MoO 4 ∙2H 2 O and 4,4′-bpy under reflux at 120 °C (4 h).…”