Co/Fe3O4@GO catalyst for one-step hydrogen generation from hydrolysis of NaBH4: Optimization and kinetic study

Abstract

In this study, cobalt nanocatalysts supported on the Fe3O4@GO were synthesized for boosting hydrogen generation upon hydrolysis of sodium borohydride. Co/Fe3O4@GO catalysts were synthesized through a facile co-precipitation method followed by a chemical reduction step. The prepared samples were characterized using various techniques including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FE-SEM), Vibrating sample magnetometer (VSM), and Nitrogen adsorption–desorption (BET). Benefiting from the high crystallinity, good dispersion of Co nanoparticles over the Fe3O4@GO, and the synergistic effect between Co nanoparticles and Fe3O4@GO support, Co/Fe3O4@GO catalysts with 30 wt% cobalt loading showed the highest catalytic activity with high hydrogen generation rate of 4000 mL/min.gcat and relatively good stability. To investigate the effect of the parameters on hydrogen generation rate and optimal reaction conditions, the Box-Behnken design under response surface methodology (RSM) was applied. ANOVA results denoted that the temperature with the highest F-value and lowest P-value had the most effect on the hydrogen generation rate. Under the optimum conditions including a temperature of 39.83 °C, 17.74 mg of catalyst, and 5.135 wt% NaBH4 concentration, Co(30%)/Fe3O4@GO exhibited a superior H2 generation rate of 6005 mL/min.gcat and low activation energy of 44.4 kJ/mol. Therefore, the Co/Fe3O4@GO is a promising catalyst for NaBH4 hydrolysis due to its easy preparation and separation method, high hydrogen generation rate, and low activation energy.