Nickel oxide nanoparticles catalyst for enhancing green hydrogen production: effect of preparation conditions

Abstract

This work focused on the synthesis of nickel oxide under varying hydrothermal conditions as a non-precious and efficient catalyst for NaBH4 hydrolysis to generate hydrogen. The structural, morphological, and textural features of the calcined samples were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and N2-physisorption techniques. XPS analysis confirmed the presence of Ni2+ and Ni3+ species, with varying Ni3+/Ni2+ ratios across the samples. The NH-200 samples showed the highest hydrogen generation rate, approximately 1290 at 323 K, attributed to the enhanced redox behavior of Ni3+ ions. N2-adsorption results revealed mesoporous structures with distinct surface areas and pore characteristics. The catalytic performance was evaluated at 35–50 °C, showing enhanced activity with increasing temperature and NaBH4 concentration (up to 4.5 wt.%). Activation energies were found to be below 59 kJ mol−1. The catalyst maintained good stability over five consecutive cycles with only a slight performance decline. These findings confirm that NiO is a cost-effective, active, and reusable catalyst for hydrogen generation via NaBH4 hydrolysis.