Controlled establishment of advanced local high-entropy NiCoMnFe-based layered double hydroxide for zinc batteries and low-temperature supercapacitors

High-entropy layered double hydroxides tailor Pt electron state for promoting acidic hydrogen evolution reaction

Despite the advancement of the Pt-catalyzed hydrogen evolution reaction (HER) through oxophilic metal-hydroxide surface hybridization, its stability in acidic solutions remains unsatisfactory. This is primarily due to excessive aggregation of active hydrogen, which hinders subsequent hydrogen desorption, coupled with the poor operational stability of metal hydroxides. In this study, we have designed Pt nanoparticles-modified NiFeCoCuCr high-entropy layered double hydroxides (Pt/HE-LDH) that exhibit exceptional catalytic activity toward HER in acidic electrolytes. Our findings reveal that the built-in electric field (BIEF) between Pt and HE-LDH facilitates the charge redistribution at Pt/HE-LDH interface, driven by the difference in work function. Additionally, effective hydrogen spillover from Pt nanoparticles to HE-LDH bidirectionally optimizes the Gibbs free energy for hydrogen adsorption. Furthermore, the interactions among the multi-metal sites, along with high entropy-induced phase stability, contribute to superior stability in acidic electrolytes. This work not only presents a straightforward strategy for enhancing hydrogen spillover from Pt but also improves the durability of metal hydroxides under acidic HER conditions.

Carbon Dot Regulating NiSe/MnO2 Heterostructures for High-Performance Supercapacitors

Structural regulation is an effective strategy for enhancing an electrode's energy storage performance. Herein, lignin-derived carbon dots (LCDs) are explored for the structural tailoring of NiSe/MnO2 to improve the electrochemical performance in supercapacitors. After the dendritic NiSe microcrystals are synthesized via a microwave method, NF/NiSe/MnO2-LCDs are prepared by another microwave process to form a composite mixture of LCDs, MnO2, and NF/NiSe. At 1 A g-1, NF/NiSe/MnO2-LCDs possess a specific capacitance of 2268 F g-1 and superb lifespans (84.43%, 3000 cycles) for their enhanced ion transport and rapid electron transfer. In addition, the NF/NiSe/MnO2-LCDs//AC ASC showed an energy density of 51.62 Wh kg-1 at 800 W kg-1 and extraordinary endurance with 88.46% retention (7000 loops). The NF/NiSe/MnO2-LCDs offer ideas to improve the capacity retention and storage capacity of electrodes for supercapacitors.

Polypyrrole and activated carbon enriched MnCo2O4 ternary composite as efficient electrode material for hybrid supercapacitors

The development of proficient electrode materials is one of the major tasks faced by modern techniques for energy storage. Integrating different materials with synergistic effects can be a valuable strategy for designing storage devices with high capacity and energy density. The spinel manganese cobaltite (MnCo2O4) is an outstanding candidate for supercapacitors owing to its remarkable pseudocapacitive behavior. However, it suffers from low electric conductivity and limited cyclic stability. To overcome its limitations, activated carbon with superior cyclic stability and polypyrrole with high electric conductivity can be incorporated in MnCo2O4. The synergistic effect of these components offers high capacitance, better conductivity, and superior cyclic performance to the ternary composite. Herein, the MnCo2O4/AC/PPY ternary composite has been synthesized by a facile approach. The optimized ternary composite (MAP-20) exhibited a wonderful capacitance of 945.77 F g-1 at five mV s-1 compared to pristine MnCo2O4 (254.98 F g-1). The real-time applicability of the optimized composite was tested with asymmetric device configuration. The asymmetric device with MAP-20 and MnO2/AC electrodes exhibited a wonderful Ed of 88.12 W h kg-1 (Pd ∼ 1.6 kW kg-1). The asymmetric device also exhibited excellent cyclic performance of 89.68% for 10 000 cycles. Further, the real-time applicability of the device was tested by illuminating a 39 red LED panel. Three asymmetric cells connected in series illuminated the panel for about 45 minutes. All these results suggest that the synergistic integration of various efficient electrode materials leads to enhanced electrochemical performance of supercapacitors.

Exploring the potential of CuCoFeTe@CuCoTe yolk-shelled microrods in supercapacitor applications

Driven by their excellent conductivity and redox properties, metal tellurides (MTes) are increasingly capturing the spotlight across various fields. These properties position MTes as favorable materials for next-generation electrochemical devices. Herein, we introduce a novel, self-sustained approach to creating a yolk-shelled electrode material. Our process begins with a metal-organic framework, specifically a CoFe-layered double hydroxide-zeolitic imidazolate framework67 (ZIF67) yolk-shelled structure (CFLDH-ZIF67). This structure is synthesized in a single step and transformed into CuCoLDH nanocages. The resulting CuCoFeLDH-CuCoLDH yolk-shelled microrods (CCFLDH-CCLDHYSMRs) are formed through an ion-exchange reaction. These are then converted into CuCoFeTe-CuCoTe yolk-shelled microrods (CCFT-CCTYSMRs) by a tellurization reaction. Benefiting from their structural and compositional advantages, the CCFT-CCTYSMR electrode demonstrates superior performance. It exhibits a fabulous capacity of 1512 C g-1 and maintains an impressive 84.45% capacity retention at 45 A g-1. Additionally, it shows a remarkable capacity retention of 91.86% after 10 000 cycles. A significant achievement of this research is the development of an activated carbon (AC)||CCFT-CCTYSMR hybrid supercapacitor. This supercapacitor achieves a good energy density (Eden) of 63.46 W h kg-1 at a power density (Pden) of 803.80 W kg-1 and retains 88.95% of its capacity after 10 000 cycles. These results highlight the potential of telluride-based materials in advanced energy storage applications, marking a step forward in the development of high-energy, long-life hybrid supercapacitors.