Flexible CuCo2O4@Ni-Co-S hybrids as electrode materials for high-performance energy storage devices

Highly Efficient and Stable Mn-Co1.29Ni1.71O4 Electrocatalysts for Alkaline Water Electrolysis: Atomic Doping Strategy for Enhanced OER and HER Performance

Water electrolysis for hydrogen production has garnered significant attention due to its advantages of high efficiency, environmental friendliness, and abundant resources. Developing cost-effective, efficient, and stable materials for water electrolysis is therefore crucial. In this work, we synthesized a series of highly efficient multifunctional Mn-Co1.29Ni1.71O4 electrocatalysts through an atomic doping strategy for alkaline electrocatalysts. The unique structure features and large specific surface area of these catalysts provide abundant active sites. The Mn-Co1.29Ni1.71O4 catalysts exhibit an excellent oxygen evolution reaction (OER) performance in 1.0 M KOH electrolyte, with an overpotential of 334.3 mV at a current density of 10 mA cm-2 and 373.3 mV at 30 mA cm-2. Additionally, the catalysts also demonstrate a Tafel slope of 76.7 mV dec-1 and outstanding durability. As hydrogen evolution reaction (HER) electrocatalysts, it shows an overpotential of 203.5 mV at -10 mA cm-2 and a Tafel slope of 113.6 mV dec-1. When the catalysts can be utilized for the overall water splitting, the catalyst requires a decomposition voltage of 1.96 V at 50 mA cm-2. These results indicate that the high catalytic activity and stability of Mn-Co1.29Ni1.71O4 samples make it a highly promising candidate for industrial-scale applications.

Highly flexible hybrid devices enabled by Ag-decorated ZnCo2O4 electrodes

Electrode materials with excellent performance are the basis for designing supercapacitors with outstanding stability and high specific capacitance. In this work, we prepared a type of ZnCo2O4 nanosheet structure with Ag nanoparticles through a multi-step hydrothermal strategy. The as-fabricated composite presented a specific capacity of 2540 F g-1 at 1 A g-1 due to the synergetic effect of its components and structure. The three-dimensional structure enabled the material to maintain an initial specific capacitance of 92.5% after 10 000 cycles. The asymmetric supercapacitor delivered an energy density of 72.36 W h kg-1 at a power density of 10 800 W kg-1. Moreover, it demonstrated 89% capacitance retention at 5 A g-1 after 10 000 cycles even when the operating temperature decreased to 0 °C.

Mesoporous NiMoO4 nanorod electrode materials for flexible and asymmetric energy storage devices

Recently, ternary metal oxides as cathode materials have been the focus of research into supercapacitors owing to their high power density and cost-efficient features. The development of excellent electrode materials is the key to improving supercapacitor total performance. Herein, we report several kinds of NiMoO4 nanostructures grown on nickel foam using a simple hydrothermal strategy. The assembled hybrid devices show an energy density of 35.9 W h kg-1 at a power density of 2708 W kg-1. After repeated charging and discharging cycling and bending tests, they show excellent durability performance and mechanical stability performance.

Production of Large Specific Capacitance by Electrodes with Low Active Mass and Synergistic Mechanisms

Decoration of vanadium nitride nanoparticles on carbon nanotubes creates electrodes with three different energy storage mechanisms that operate synergistically to give a high specific capacitance with a low active mass. Calculation and measurements further indicate the power and energy density to be as high as 105-106 W/kg and 102 Wh/kg, respectively. Particle attachment also greatly improves the capacitive coefficient, including ionic transmittance, charge transfer, porosity, and conductivity. Corrosion tests based on the Tafel method reveal the corrosion potential and current of electrodes as low as -0.721 V and 7.53 × 10-4 A, respectively.

Nanostructured Electrodes for High-Performance Supercapacitors and Batteries

Emerging renewable energy sources have received extensive attention in the past few decades [...].

NiMoO4 Nanosheets Embedded in Microflake-Assembled CuCo2O4 Island-like Structure on Ni Foam for High-Performance Asymmetrical Solid-State Supercapacitors

Micro/nano-heterostructure with subtle structural design is an effective strategy to reduce the self-aggregation of 2D structure and maintain a large specific surface area to achieve high-performance supercapacitors. Herein, we report a rationally designed micro/nano-heterostructure of complex ternary transition metal oxides (TMOs) by a two-step hydrothermal method. Microflake-assembled island-like CuCo2O4 frameworks and secondary inserted units of NiMoO4 nanosheets endow CuCo2O4/NiMoO4 composites with desired micro/nanostructure features. Three-dimensional architectures constructed from CuCo2O4 microflakes offer a robust skeleton to endure structural change during cycling and provide efficient and rapid pathways for ion and electron transport. Two-dimensional NiMoO4 nanosheets possess numerous active sites and multi-access ion paths. Benefiting from above-mentioned advantages, the CuCo2O4/NiMoO4 heterostructures exhibit superior pseudocapacitive performance with a high specific capacitance of 2350 F/g at 1 A/g as well as an excellent cycling stability of 91.5% over 5000 cycles. A solid-state asymmetric supercapacitor based on the CuCo2O4/NiMoO4 electrode as a positive electrode and activated carbon as a negative electrode achieves a high energy density of 51.7 Wh/kg at a power density of 853.7 W/kg. These results indicate that the hybrid micro/nanostructured TMOs will be promising for high-performance supercapacitors.

Hierarchical Design of CuO/Nickel-Cobalt-Sulfide Electrode by a Facile Two-Step Potentiostatic Deposition

Herein, a scalable electrodeposition strategy is proposed to achieve hierarchical CuO/nickel-cobalt-sulfide (NCS) electrodes using two-step potentiostatic deposition followed by high-temperature calcination. The introduction of CuO provides support for the further deposition of NSC to ensure a high load of active electrode materials, thus generating more abundant active electrochemical sites. Meanwhile, dense deposited NSC nanosheets are connected to each other to form many chambers. Such a hierarchical electrode prompts a smooth and orderly transmission channel for electron transport, and reserves space for possible volume expansion during the electrochemical test process. As a result, the CuO/NCS electrode exhibits superior specific capacitance (Cs) of 4.26 F cm^-2 at 20 mA cm^-2 and remarkable coulombic efficiency of 96.37%. Furthermore, the cycle stability of the CuO/NCS electrode remains at 83.05% within 5000 cycles. The multistep electrodeposition strategy provides a basis and reference for the rational design of hierarchical electrodes to be applied in the field of energy storage.

High-efficiency NiCo layered double hydroxide electrocatalyst

We report several kinds of NiCo-LDH composites by a hydrothermal reaction and subsequent electrodeposition process. The prepared NiCo-LDH@PEDOT-200 sample shows an overpotential of 52 mV for the HER at 10 mA cm−2 in 1.0 M KOH.