Bimetallic Ag-Ni nanoparticles as an effective catalyst for hydrogen generation from hydrolysis of sodium borohydride

Abstract

Stable Ag-Ni bimetallic NPs was prepared, characterized, and applied for the dehydrogenation of sodium borohydride in aqueous media. The structure morphology and properties of Ag-Ni NPs were characterized by using conventional techniques such as surface field scanning electron microscopy (FESEM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV–visible spectroscopy, energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy. The Ag-Ni NPs were found to be highly effective catalyst to the hydrogen generation from the hydrolysis of sodium borohydride. The catalytic activity of Ag-Ni was increased with increasing the ratio of Ni (Ag25-Ni25 ˂ Ag25-Ni50 ˂ Ag25-Ni75). The reaction follows first-order kinetics with respect to [NaBH4]. The apparent activation energy = 16.2 kJ/mol, activation enthalpy = 13.4 kJ/mol, and activation entropy = −135.2 J/K/mol were calculated for the hydrogen generation. The activation energy is much lower than those of the other bimetallic nano catalysts. The excellent catalytic activity, good stability, and low cost make the Ag based Ag-Ni NPs a suitable catalyst for the generation of hydrogen in sodium borohydride hydrolysis. It was found that the Ag25-Ni75 is one of the most reusable and durable catalyst for six consecutive cycles without any significant decrease in their catalytic activity.