Synthesis of bimetallic NixCo1-xP hollow nanocages from metal-organic frameworks for high performance hybrid supercapacitors

MOF-Derived Transition Metal Phosphides for Supercapacitors

Transition metal phosphides (TMPs) in supercapacitors (SCs) applications are increasingly attracting attention because of their exceptional electrochemical performance. MOF-derived TMPs, possess high specific surface areas, rich pore structure, and controllable chemical compositions, offering promising opportunities for supercapacitor applications. There is a wide variety of MOF-derived TMPs, and they exhibit different properties in SCs. This work mainly categorizes MOF-derived TMPs (FexP, CoxP, NixP, NixCoyP, CuxP), and then outlines the latest research advancements regarding their use as electrode materials in SCs, including the latest results of synthesis methods and structural modulation. Subsequently, the applications of MOF-derived TMPs as electrode materials in SCs are discussed. At the end, perspectives of future developments and key challenges in the applications of MOF-derived TMPs in SCs are highlighted, with the aim of providing guidance for future research.

Multimetallic transition metal phosphide nanostructures for supercapacitors and electrochemical water splitting

Transition metal phosphides (TMPs) have recently emerged as an important class of functional materials and been demonstrated to be outstanding supercapacitor electrode materials and catalysts for electrochemical water splitting. While extensive investigations have been devoted to monometallic TMPs, multimetallic TMPs have lately proved to show enhanced electrochemical performance compared to their monometallic counterparts, thanks to the synergistic effect between different transition metal species. This topical review summarizes recent advance in the synthesis of new multimetallic TMP nanostructures, with particular focus on their applications in supercapacitors and electrochemical water splitting. Both experimental reports and theoretical understanding of the synergy between transition metal species are comprehensively reviewed, and perspectives of future research on TMP-based materials for these specific applications are outlined.

Rhenium Sulfide Incorporated in Molybdenum Sulfide Nanosheets for High-Performance Symmetric Supercapacitors with Enhanced Capacitance

Supercapacitors are considered potential energy storage devices and have drawn significant attention due to their superior intrinsic advantages. Herein, we report the synthesis of ReS₂ embedded in MoS₂ nanosheets (RMS-31) by a hydrothermal technique. The prepared RMS-31 electrode material demonstrated superior pseudocapacitive behavior in 1 M KOH electrolyte solution, which is confirmed by the heterostructure of RMS-31 nanosheet architectures. RMS-31 has a specific capacitance of 244 F g^-1 at a current density of 1 A g^-1 and a greater areal capacitance of 540 mF cm^-2 at a current density of 5 mA cm^-2. The symmetric supercapacitor device with the RMS-31 electrode delivers an energy density of 28 W h cm^-2 with a power density of 1 W cm^-2 and reveals long-term stability at a constant current density of 5 mA cm^-2 for 10,000 cycles while accomplishing a retention of 66.5%. The high performance of this symmetric device is attributed to the synergistic effect of ReS₂ and MoS₂ and the presence of the metallic 1T-MoS₂ phase in the RMS-31 electrode. To the best of our knowledge, this is the first report of increasing the interlayer spacing of 2H-MoS₂ by incorporating ReS₂ for symmetric supercapacitor applications.

Facile fabrication of core-shell structured Ni(OH)2/Ni(PO3)2 composite via one-step electrodeposition for high performance asymmetric supercapacitor

Metal metaphosphates, particularly those with core-shell structure, have showed extraordinary potential in energy storage field due to their superior chemical and physical properties. However, the core-shell metal metaphosphates with high energy density in supercapacitor application is rarely reported. Here, the core-shell structured Ni(OH)₂/Ni(PO₃)₂ (NNP) hybrid electrode were prepared by one-step electrodeposition, which exhibits a superior specific capacitance of 1477 F g^-1 at a current density of 1 A g^-1. Furthermore, an aqueous asymmetric supercapacitor (ASC) based on NNP hybrid composite as cathode and reduced graphene oxide (rGO) as anode is assembled successfully to deliver a prominent energy density of 67 Wh kg^-1 at 775 W kg^-1 and splendid stability with capacitance retention of 81% after 8000 cycles. The outstanding electrochemical capabilities are attributed to the porous nanoflake and hierarchical core-shell structure of NNP hybrid composite, which can accelerate ion diffusion and charge transfer in redox reaction. These results indicate that nanohybrid NNP material has promise to be an advanced energy storage material.

Recent Progress in Two-Dimensional Layered Double Hydroxides and Their Derivatives for Supercapacitors

High-performance supercapacitors have attracted great attention due to their high power, fast charging/discharging, long lifetime, and high safety. However, the generally low energy density and overall device performance of supercapacitors limit their applications. In recent years, the design of rational electrode materials has proven to be an effective pathway to improve the capacitive performances of supercapacitors. Layered double hydroxides (LDHs), have shown great potential in new-generation supercapacitors, due to their unique two-dimensional layered structures with a high surface area and tunable composition of the host layers and intercalation species. Herein, recent progress in LDH-based, LDH-derived, and composite-type electrode materials targeted for applications in supercapacitors, by tuning the chemical/metal composition, growth morphology, architectures, and device integration, is reviewed. The complicated relationships between the composition, morphology, structure, and capacitive performance are presented. A brief projection is given for the challenges and perspectives of LDHs for energy research.

High Capacity and Energy Density of Zn-Ni-Co-P Nanowire Arrays as an Advanced Electrode for Aqueous Asymmetric Supercapacitor

Developing multicomponent transition-metal phosphides has become an efficient way to improve the capacitive performance of single-component transition-metal phosphides. However, reports on quaternary phosphides for supercapacitor applications are still scarce. Here, we report high capacity and energy density of Zn-Ni-Co-P quaternary phosphide nanowire arrays on nickel foam (ZNCP-NF) composed of highly conductive metal-rich phosphides as an advanced binder-free electrode in aqueous asymmetric supercapacitors. In a three-electrode system using the new electrode, a high specific capacity of 1111 C g^-1 was obtained at a current density of 10 A g^-1. Analysis of this aqueous asymmetric supercapacitor with ZNCP-NF as the positive electrode and commercial activated carbon as the negative electrode reveals a high energy density (37.59 Wh kg^-1 at a power density of 856.52 W kg^-1) and an outstanding cycling performance (capacity retention of 92.68% after 10 000 cycles at 2 A g^-1). Our results open a path for a new design of advanced electrode material for supercapacitors.

The one-step electrodeposition of nickel phosphide for enhanced supercapacitive performance using 3-mercaptopropionic acid

TMPs have received considerable attention for various applications, including the water splitting reaction (hydrogen evolution reaction and oxygen evolution reaction), methanol oxidation, the oxygen reduction reaction, rechargeable batteries, and supercapacitors.