Synthesis and characterization of Ni2C: An efficient electrocatalyst towards hydrogen evolution reaction

Ni2C electrocatalyst were synthesized and characterized for the Hydrogen Evolution Reaction (HER) electrolyzer. One step hydrothermal technique is used to synthesize Ni2C sample. Platinum based electro catalyst materials are initial and best electro catalyst for Hydrogen Evolution Reaction (HER). Ni2C (Nickel Carbide electro catalyst) was examined by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD). Electrochemical characterization like cyclic voltammetry (CV), Tafel polarization and electrochemical impedance spectroscopy (EIS) studies is employed to explore the elctrocatalytic behavior of Ni2C material for HER. FTIR study confirms the presence of Ni2C electrocatalyst by the presence of metal peaks and various functional groups. The isomeric nature and purity of synthesized material were explored by powder X-ray diffraction studies. Cyclic voltammetry technique was performed in 0.5 M H2SO4 solution to attain the polarization curve of Ni2C electrocatalyst for HER.

Synthesis and Compressibility of Novel Nickel Carbide at Pressures of Earth’s Outer Core

We report the high-pressure synthesis and the equation of state (EOS) of a novel nickel carbide (Ni3C). It was synthesized in a diamond anvil cell at 184(5) GPa through a direct reaction of a nickel powder with carbon from the diamond anvils upon heating at 3500 (200) K. Ni3C has the cementite-type structure (Pnma space group, a = 4.519(2) Å, b = 5.801(2) Å, c = 4.009(3) Å), which was solved and refined based on in-situ synchrotron single-crystal X-ray diffraction. The pressure-volume data of Ni3C was obtained on decompression at room temperature and fitted to the 3rd order Burch-Murnaghan equation of state with the following parameters: V0 = 147.7(8) Å3, K0 = 157(10) GPa, and K0' = 7.8(6). Our results contribute to the understanding of the phase composition and properties of Earth’s outer core.

Phase and interface engineering of nickel carbide nanobranches for efficient hydrogen oxidation catalysis

A heterogeneous Ni/Ni3C interface has been constructed through carefully annealing a classic metal carbide of Ni3C, where the strong interfacial synergy can regulate the binding strengths of *H and *OH and thus enhance the HOR performance.

Self-standing heterostructured NiC x -NiFe-NC/biochar as a highly efficient cathode for lithium–oxygen batteries

Lithium–oxygen batteries have attracted research attention due to their low cost and high theoretical capacity. Developing inexpensive and highly efficient cathode materials without using noble metal-based catalysts is highly desirable for practical applications in lithium–oxygen batteries. Herein, a heterostructure of NiFe and NiC x inside of N-doped carbon (NiC x -NiFe-NC) derived from bimetallic Prussian blue supported on biochar was developed as a novel self-standing cathode for lithium–oxygen batteries. The specific discharge capacity of the best sample was 27.14 mAh·cm−2 at a stable discharge voltage of 2.75 V. The hybridization between the d-orbital of Ni and s and p-orbitals of carbon in NiC x , formed at 900 °C, enhanced the electrocatalytic performance due to the synergistic effect between these components. The structure of NiC x -NiFe-NC efficiently improved the electron and ion transfer between the cathode and the electrolyte during the electrochemical processes, resulting in superior electrocatalytic properties in lithium–oxygen batteries. This study indicates that nickel carbide supported on N-doped carbon is a promising cathode material for lithium–oxygen batteries.

Chemical Reduction Behaviour of NiO under Various Concentration of Carbon Monoxide Using TPR and XRD Techniques

The chemical reduction behavior of NiO under various carbon monoxide (CO) concentration as a reduction agent was studied. The NiO and Ni0 transformations were identified using TPR and XRD techniques. It was shown that, the completed reduction occurred at temperature 700 °C for 40% CO and 900 °C for 10% and 20% CO. During the chemical reduction process, nickel carbide was formed at temperature 400 °C and another formation of carbon amorphous appeared at 500 °C and proved through diffraction of XRD pattern at 2θ: 22.86 under 20% CO/N2 and and 2θ: 26.15 under 40% CO/N2. The interpretation of physisorption data showed that the pore size after reduction with various CO concentration comprised as microporous size in the range of 6-40 nm. Therefore, CO as a mild reduction agent stated that as the concentration of CO high, the rate of reduction affected and formed a very crystalline of Ni0 particle.