nickel nitride is an air-stable nitride compound that exhibits high reactivity in a wide range of oxidative reactions. It is a promising candidate as an electrocatalyst for energy-related applications. It has low overpotential and high current density and is stable in alkaline solutions. It also possesses excellent activity in oxygen evolution (OER) and reduction (ORR) reactions, which are essential for electrolysis of water.
Ni nitride is synthesised in a safe and inexpensive manner through the direct formation of nickel nitride nanostructures from molten salt melt. These nitride nanostructures provide a high surface area and can be used as effective self-supported HER catalysts.
In this study, Ni foams were nitrided with nitrogen plasma using microwave at a temperature of 400 degC for 1 h to prepare nickel nitride (Ni3N1- x/NF). The samples were characterized by X-ray diffraction and X-ray photoelectron spectroscopy.
During the plasma treatment, a closed Ni3N layer was formed, with a distinct compressive macrostrain parallel to the surface (Fig. S4). The intensity of this peak decreased and almost vanished at higher temperatures. This could be attributed to the elastic anisotropy of Ni3N.
To further characterize the nitrided Ni foam, we prepared a reference sample by heating NF in ammonia atmosphere at 450 degC for 1 h (Ni3N/NF). The X-ray diffraction patterns (Figure S4, Supporting information) showed that the sample was nitrided with hexagonal Ni3N (JCPDS: 10-0280). HRTEM analysis showed that the surface of the Ni foam was covered with a thin layer containing small particles with lattice fringes corresponding to Ni3N.