Ultrafine Amorphous Co–Fe–B Catalysts for the Hydrolysis of NaBH4 Solution to Generate Hydrogen for PEMFC

For hydrogen generation from alkaline sodium borohydride (NaBH₄) solution, Co–Fe–B catalysts with different Co/(Co + Fe) molar ratios (χ_Co) were prepared by the chemical reduction of CoCl₂ and FeCl₃ ethanol solution with KBH₄ solution. The X‐ray diffraction (XRD) and scanning electron microscopy (SEM) analyses revealed that the as‐prepared Co–Fe–B catalysts were in amorphous form and ultrafine. The hydrogen generation measurements showed that as‐prepared Co–B and Co–Fe–B catalysts exhibited excellent catalytic activity. Co–Fe–B with the Co/(Co + Fe) molar ratio (χ_Co) of 0.85 was the best. Its maximum hydrogen generation rate at 298 K was 4,310 mL min^–1 g^–1, while the Co–B was 2,773 mL min^–1 g^–1. The enhanced activity could be attributed to large active surface area, electron transfer from B and Fe to active Co sites, and improvement in the dispersion of Co–B with Fe₂O₃. The activation energy of Co–Fe–B catalyst with the molar ratio χ_Co = 0.85 was decreased to 29.09 kJ mol^–1 as compared to 30.85 kJ mol^–1 obtained with Co–B.