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[Display omitted] • The porous lamellar GO/Ni 2 ZnS 4 @NiCo 2 S 4 was prepared using simple ZIF-8@ZIF-9 templating method. • The core–shell structure of graphene trimetallic sulfides was synthesized for the first time. • GO/Ni 2 ZnS 4 @NiCo 2 S 4 inherits the high specific surface area of the ZIF template and the high pseudocapacitance of the sulfide. • High specific capacity of 2284F/g were achieved at the current density of 1 A/g. Metal-organic frameworks (MOFs) have emerged as promising active electrode materials in supercapacitors for its controllable porous structure and excellent physio-chemical properties. However, the poor conductivities keep it from achieving its full capacitance potential, which greatly limits its practical application. Here, a facile pathway is reported to fabricate the GO/Ni 2 ZnS 4 @NiCo 2 S 4 composite with large specific surface area and favorable electrical conductivity. Thanks to the novel tremella-like core–shell structure and high-efficient synergistic effects among multi-components, the designed GO/Ni 2 ZnS 4 @NiCo 2 S 4 electrode shows a high specific capacitance of 2284 F/g at 1 A/g. Furthermore, the asymmetric supercapacitor fabricated by coupling GO/Ni 2 ZnS 4 @NiCo 2 S 4 positive electrode with biological carbon negative electrode achieves a remarkable energy density of 120 Wh kg−1 at a power density of 750 W kg−1. [ABSTRACT FROM AUTHOR]

As a branch of MOF, MIL has attracted much attention in the field of electrochemistry because of its high porosity and potential high charge storage capacity. Graphene oxide is considered as an ideal supercapacitor material because of its high electrical conductivity, high specific surface area and rich surface functional groups. The metal sulfides prepared with MIL as template not only inherit the structural characteristics of MIL, but also improve the electrical conductivity of the materials, which thus show excellent energy storage properties. In this work, the rGO/Cu 0.76 Fe 0.24 S 2 composite was prepared through in-situ growth of MIL-101 on the surface of GO followed by copper nitrate etch, high temperature carbonization and hydrothermal sulfurization. To the best of our knowledge, it is the first time to report that rGO/Cu 0.7 Fe 0.3 S 2 is used as the electrode of supercapacitor and tested for energy storage. The optimized rGO/Cu 0.7 Fe 0.3 S 2 electrode exhibited good capacitive performances, including high specific capacitance of 661.2 F g−1 at 1 Ag−1 and remarkable cycle stability with 69 % after 5000 cycles. Employing the as-prepared rGO/Cu 0.7 Fe 0.3 S 2 composites as positive electrode, the hybrid supercapacitor device displayed spectacular capacity of energy density (54.37 Wh kg−1), great power density (887.75 W kg−1) and impressive long-term stability of 70 % retention after 5000 cycles. The results show that the composite prepared with graphene oxide as substrate and MIL-101 (Fe) as template should be a promising materials for fabricating high-performance supercapacitor. [Display omitted] • The preparation of GO-based metal sulfides as energy storage devices using MIL-101(Fe) as a template was investigated for the first time. • rGO/Cu 0.7 Fe 0.3 S 2 has a good charge-discharge cycle with a capacitance retention of 69 % (5000 cycles). • The electrochemical performance of rGO/Cu 0.7 Fe 0.3 S 2 is excellent, reaching 661.2 F g−1 (current density: 1 A g−1). • The asymmetric device constructed from AC and rGO/Cu 0.7 Fe 0.3 S 2 provides an energy density of 54.37 Wh kg−1 (power density: 887.75 W kg−1). [ABSTRACT FROM AUTHOR]

[Display omitted] • The porous lamellar rGO/NiCo 2 S 4 was prepared using simple ZIF-9 templating method. • Bimetallic sulfides have more active pseudocapacitors than monometallic sulfides. • rGO/NiCo 2 S 4 inherits the high specific surface area of the ZIF template and the high pseudocapacitance of the sulfide. • High specific capacity of 1242.4 F g−1 were achieved at the current density of 1 A g−1. Transition metal sulfide is considered as one of the best materials for high-performance supercapacitors because of its excellent conductivity, high theoretical specific capacitance and good thermal stability. Herein, the reduction graphene oxide supported NiCo 2 S 4 (rGO/NiCo 2 S 4) nanomaterial was successfully fabricated at ambient temperature via a facile strategy. Three-dimensional ZIF-9 was used as a tem-plate, graphene oxide was used as the supporting material and Ni(NO 3) 2 was used as both etchant and Nickel source. As a result, the prepared materials shows a high specific capacitance of 1242.2 F g−1 at a current density of 1 A g−1. Besides, the assembled active carbon (AC)//rGO/NiCo 2 S 4 asymmetric supercapacitor delivered a high energy density of 79.87 Wh kg−1 with a power density of 750 W kg−1 and a capacity retention of 58.5% after 5000 cycles. This work demonstrates an simple design pathway to manufacture bimetallic sulfide and provides basic research for the application of bimetallic sulfide with high surface area and high electrochemical activity used in supercapacitors. [ABSTRACT FROM AUTHOR]

• Layered porous nanomaterial rGO/Cr 2 ZnS 4 was prepared by etching GO/ZIF-8. • Go-based GrZn bimetallic sulfide exhibits excellent energy storage properties. • The electrochemical performance of rGO/Cr 2 ZnS 4 -2h is much better than that of rGO/ZnS. • The specific capacitance of rGO/Cr 2 ZnS 4 -2h can reach 958.6 F g−1 (Current density: 1 A g−1). • AC//rGO/Cr 2 ZnS 4 -2h asymmetric supercapacitor can provide a high energy density of 47.7 Wh kg−1. In this work, rGO/Cr 2 ZnS 4 composites was composited with reduced GO using ZIF-8 as the template. Firstly, GO/ZIF-8 was obtained by in-situ synthesis strategy, and then ZIF-8 was etched by chromium nitrate to obtain CrZn-LDH. Finally, rGO/Cr 2 ZnS 4 was successfully synthesized after calcination and sulfuration. Due to the synergistic effect between Cr 2 ZnS 4 and rGO, the hybrid electrode has significantly improved energy storage capacity in terms of the high specific capacitance of 958.6 F g−1 at 1 A g−1 and good cycling stability after 10,000 cycles (63.1 % of the initial value under 10 A g−1) in a three-electrode system. Meanwhile, the asymmetric supercapacitor was prepared using rGO/Cr 2 ZnS 4 composite as the positive electrode and AC (active carbon) as the negative electrode. The fabricated asymmetric supercapacitor has high energy density of 47.7 Wh kg−1 at power density of 749.54 W kg−1 and capacity retention of 50 % after 5000 cycles. This work offers a promising approach for designing advanced hybrid materials of transition metal sulfides for high energy density supercapacitors. [Display omitted] [ABSTRACT FROM AUTHOR]

As a new environment-friendly energy storage system between traditional capacitors and lithium-ion batteries, supercapacitors have many excellent characteristics compared with other energy storage devices. The new electrode material is the key component to determine the performance of the supercapacitor. Combined with the relevant literature reports of researchers in recent years, the structure and properties of Co, Zn, Ni and other materials were introduced, and the preparation method of Co–Zn as electrode material was sorted out. The rGO/Zn 0.773 Co 0.227 S composites were prepared by a simple template method to analyze the structure and morphology, and rGO/Zn 0.773 Co 0.227 S was treated to make it a paste adhering to nickel foam. Benefiting from the synergistic effect between Zn 0.773 Co 0.227 S and rGO, the composite provides significantly improved energy storage capability in a three-electrode system. The specific capacitance can reach 1680 ​F ​g−1 at the current density of 1 ​A ​g−1. When the current density is increased to 10A g−1, the specific capacitance still reaches 895.4 ​F ​g−1, and the loss of the specific capacitance is only 22.2% after 5000 cycles at 10 ​A ​g−1. When rGO/Zn 0.773 Co 0.227 S is used as cathode material and AC as negative material, asymmetric supercapacitor also has good cycle stability and high energy density. [Display omitted] • The novel layered porous nanomaterial rGO/Zn 0.773 Co 0.227 S was prepared by etching GO/ZIF-8 template. • The electrochemical properties of cobalt-zinc bimetallic sulfides loaded on graphene were investigated for the first time. • The electrochemical performance of the rGO/Zn 0.773 Co 0.227 S could be influenced by etching time. • The rGO/Zn 0.773 Co 0.227 S-2h could reach an optimum specific capacitance of 1680 ​F ​g−1 (current density: 1 ​A ​g−1). [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) was used as a substrate, and ZIF-8 was grown in situ on the GO surface and used as a template. The rGO/Ni 2 ZnS 4 composite was prepared by nickel nitrate etching, carbonization, and hydrothermal vulcanization. X-ray diffraction (XRD), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize the structure and morphology of the composite material. Then the rGO/Ni 2 ZnS 4 composite material was made into a cathode material, and its electrochemical performance was tested. The test results showed that the specific capacitance value of the rGO/Ni 2 ZnS 4 -1.5h electrode material was as high as 1150 F·g−1 at a current density of 1 A·g−1, when the current density reaches 10 A·g−1, the rate performance is 63.3%. After 2000 cycles at a current density of 10 A·g−1, the capacitance retention rate is 59.7%. In addition, an asymmetric capacitor composed of AC//rGO/Ni 2 ZnS 4 -1.5h has an energy density of 31.06 Wh·kg−1, when the power density is 750.44 W·kg−1. When the high power density is 7489.18 W·kg−1, the energy density remains at 12.69 Wh·kg−1. [Display omitted] • The rGO/Ni 2 ZnS 4 composites material derived from GO and ZIF-8. • Core-shell rGO/Ni 2 ZnS 4 directly grows on Ni foam. • The rGO/Ni 2 ZnS 4 exhibited a specific capacitance of 1150 F/g. • The rGO/Ni 2 ZnS 4 device possessed high energy density. [ABSTRACT FROM AUTHOR]

• CoMn-LDH/ZIF-67/PANI with network structure was prepared. • The influence of CoMn-LDH on the stability of ZIF-67 was discussed. • The influence of PANI on the conductivity of CoMn-LDH/ZIF-67 was explored. • The specific capacitance of CoMn-LDH/ZIF-67/PANI can reach 1048 F g−1 at 1 A g−1. Metal-organic framework materials (MOFs) are widely used in electrochemical energy storage due to their abundant active sites and high redox activity. Especially in the field of supercapacitors, the porous structure of MOFs makes them the most promising candidates for composite electrode materials due to their vast specific surface area. However, the poor chemical stability of MOFs in alkaline electrolytes limits their application. Constructing and improving the stability of metal-organic backbone materials through rational structural design is the key to enhancing the electrochemical performance of capacitors. In this paper, the stability of ZIF-67 was enhanced by the complexing with bimetallic hydroxide (CoMn-LDH), and the conductivity is further enhanced by the mixing of polyaniline (PANI) to form a ''network structure'' morphology. As a result, the composite electrode material has a specific capacity of 1048 F g−1 at 1 A g−1 with a good cycle life (80.5 % capacity retention for 5000 cycles). The specific capacity of the CoMn-LDH/ZIF-67/PANI//AC asymmetric supercapacitor (ASC) was 164 F g−1 at 1 A g−1 in the voltage range of 0–1.5 V. The maximum energy density of the ASC was 51.25 Wh kg−1 at a power density of 2250 W kg−1. In addition, excellent cycling stability (71.2 % capacitance retention after 5000 cycles) was delivered. [Display omitted] [ABSTRACT FROM AUTHOR]