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 (chi(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 (chi(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 chi(Co) = 0.85 was decreased to 29.09 kJ mol(-1) as compared to 30.85 kJ mol(-1) obtained with Co-B.