Hydrothermal preparation of MoS 2 nanoflake arrays on Cu foil with enhanced supercapacitive property

Ru-Ni nanoparticles electrodeposited on rGO/Ni foam as a binder-free, stable and high-performance anode catalyst for direct hydrazine fuel cell

Bimetallic Ru-Ni nanoparticles was synthesized on the reduced graphene oxide decorated Ni foam (Ru-Ni/rGO/NF) by electroplating method to be utilized as the anode electrocatalyst for direct hydrazine-hydrogen peroxide fuel cells (DHzHPFCs). The synthesized electrocatalysts were characterized by X-ray diffraction, Field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. The electrochemical properties of catalysts towards hydrazine oxidation reaction in an alkaline medium were evaluated by cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. In the case of Ru₁-Ni₃/rGO/NF electrocatalyst, Ru₁-Ni₃ provided active sites due to low activation energy (22.24 kJ mol^-1) for hydrazine oxidation reaction and reduced graphene oxide facilitated charge transfer by increasing electroactive surface area (EASA = 677.5 cm²) with the small charge transfer resistance (0.1 Ω cm²). The CV curves showed that hydrazine oxidation on the synthesized electrocatalysts was a first-order reaction in low concentrations of N₂H₄ and the number of exchanged electrons was 3.0. In the single cell of the of direct hydrazine-hydrogen peroxide fuel cell, the maximum power density value of Ru₁-Ni₃/rGO/NF electrocatalyst was 206 mW cm^-2 and the open circuit voltage was 1.73 V at 55 °C. These results proved that the Ru₁-Ni₃/rGO/NF is a promising candidate for using as the free-binder anode electrocatalyst in the future application of direct hydrazine-hydrogen peroxide fuel cells due to its excellent structural stability, ease of synthesis, low cost, and high catalytic performance.

Rational Design of Novel Efficient Palladium Electrode Embellished 3D Hierarchical Graphene/Polyimide Foam for Hydrogen Peroxide Electroreduction

The electrocatalytic applications of traditional polyimide film and carbon nanomaterials are hindered due to a shortage of three-dimensional hierarchical conductivity and porous structure. Herein, a novel polyimide-based electrode based on a highly efficient palladium nanocatalyst embellished three-dimensional reduced graphene oxide/polyimide foam (Pd/3D RGO@PI foam, signed PRP) toward H₂O₂ electroreduction was designed and prepared through thermal foaming procedure, followed by facile dip-drying method and electrodeposition. As expected, such a binder-free, 3D hierarchical structure PRP electrode presented high catalytic property, good stability, as well as low activation energy toward H₂O₂ electroreduction during the electrochemical measurement period. The PRP electrode showed a reduction current density of 810 mA·cm^-2 at -0.2 V (vs Ag/AgCl) in 2.0 mol·L^-1 H₂SO₄ and 2.0 mol·L^-1 H₂O₂. Moreover, the PRP electrode also illustrated good reproducibility and repeatability. Reproducibility presented almost 95.8% of the initial current density after 1000 cycles test. Also, the activation energy of H₂O₂ electroreduction on 3D PRP electrode was 21.624 kJ·mol^-1. Benefiting from the 3D hierarchical structure and efficient catalyst, the PRP electrode exhibited excellent electrocatalytic performance and was considered to be a potential candidate material for fuel cells.