Effect of Titanium Dioxide Support for Cobalt Nanoparticle Catalysts for Hydrogen Generation from Sodium Borohydride Hydrolysis

The influence of the structural differences in titanium dioxide (TiO2- Degussa P25 and Mesh 325) as supporting materials for cobalt (Co) nanoparticles, has been revealed in aqueous and alkaline sodium borohydride (NaBH4) hydrolysis. The very little amount of Co nanoparticles, which was 2.2 and 1.5 wt%, has been successfully embedded on TiO2 (P25) and TiO2 (Mesh 325), respectively, via facile impregnation and magnetic separation method. The activation energies for TiO2 (Mesh 325)/Co and TiO2 (P25)/Co catalysts in the aqueous solution of NaBH4 were 64.3 kJ.mol(-1) and 56.76 kJ.mol(-1), respectively. On the other hand, the activation energy values of the hydrolysis process in alkaline NaBH4 solutions using TiO2 (Mesh 325)/Co and TiO2 (P25)/Co catalysts have been calculated as 55 kJ.mol(-1) and 45.2 kJ.mol(-1), respectively. Consequently, the hydrogen generation rate (HGR) for TiO2(Mesh 325)/Co and TiO2(P25)/Co in an aqueous-alkaline solution are 360 and 660 mL.min.gcat(-1), respectively which are twice higher in that of aqueous NaBH4 hydrolysis reaction. The maximum HGR of 9000 mL.min(-1).gcat(-1) for TiO2(P25) loaded with 2.2 wt% Co in an aqueous-alkaline solution at 60 degrees C, indicates this catalysis is very promising as the cost-effective catalytic hydrolysis of NaBH4.