Synthesis of Ni/NiO nanocomposites by imidazole-assisted solution combustion method for hydrogen evolution reaction
摘要
In the present paper, Ni/NiO nanocomposite was synthesized by a facile onestep solution combustion method of nickel nitrate in the presence of imidazole reductant agent. The obtained material was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray with mapping, Raman spectroscopy, and X-ray photoelectron spectroscopy. The physicochemical characterization confirms the presence of the nanoparticles NiO and Ni with crystalline size from 9 nm to 50 nm. The experimental data also illustrates that the particle size as well as the ratio of the two phases Ni and NiO in the obtained nanocomposite can be controlled by changing the nickel/imidazole molar ratio and calcination conditions (temperature and time). The catalytic activity and stability of Ni/NiO nanocomposite on hydrogen evolution reaction were examined in 1 M NaOH solution. It was observed that Ni/NiO nanocomposite derived from the combustion of nickel/imidazole with molar ratio of 1:2 at 350 °C for 20 min showed the best catalytic activity with the overpotential of 254 mV at the current density of 10 mA cm-2 and Tafel slope of 118 mV dec-1. This indicates that a synergistic effect between NiO and Ni particles could enhance the hydrogen evolution performance of the electrocatalyst.
Graphical Abstract