Investigation on the effect of synthesizing temperature on the catalytic activity of nickel cobalt boron catalysts in sodium borohydride hydrolysis process

Hydrogen production through the reaction between sodium borohydride (NaBH₄) and water in presence of three different catalysts including; NiB, CoB and NiCoB is studied. The catalysts are synthesized by chemical reduction method at room and 0 °C temperature. The products are characterized by X-Ray Diffraction (XRD), High-Resolution Scanning Electron Microscopy (HRSEM) and Inductively Coupled Plasma-optical emission spectroscopy (ICP). The results showed that carrying out synthesizing process at low temperature, causes decreasing the nuclei size and reducing driving force for the growth stage, and results in a meaningful reduction in size of the produced catalysts particles. Furthermore, it leads to a recognizable change in particles shape to fine spherical with definite boundaries and slightly increase in boron content of each catalyst. These changes, especially in size and shape of the produced catalysts, results in an improvement in catalytic activity of the synthesized catalysts and the rate of hydrogen generation through using them. This achievement were successfully proved for all three NiB, CoB and NiCoB catalysts, although it was more pronounced for CoB so that it was possible to produce 1.4 lit hydrogen in less than 13 s (12,923 ml·min^?1.g^?1_catalyst) by using 0.5 g of CoB catalyst synthesized at 0 °C.