CoB supported on Ag-activated TiO2 as a highly active catalyst for hydrolysis of alkaline NaBH4 solution

Abstract

In this study, a series of TiO2 (activated by Ag) supported CoB catalysts were synthesized using electroless deposition method. Compared to the unsupported CoB catalyst, the CoB/Ag–TiO2 catalysts showed much better catalytic activity and higher stability on hydrolysis of NaBH4 in alkaline aqueous solution and the catalysts were insensitive to air oxidation. The optimistic loading amount of CoB was 2.8 wt% and its hydrogen generation rate reached 6294 mL min−1 (g Co)−1 in 1 wt% NaBH4 + 5 wt% NaOH solution at 293 K. The catalytic activity was comparable to some noble catalysts and could retain nearly 70% after 5 cycles. The catalysts were studied by varies techniques and the results revealed that the dispersion of CoB was improved and the CoB/Ag–TiO2 catalysts possessed distinct porous structure which could promote the diffusion of reactants/products. The surface composition and the electron transfer effects between the Co0 with B0 and Ag0 could also affect the catalytic activity. Under the current experimental conditions, the specific activation energy of 2.8CoB/Ag–TiO2 catalyst was determined as 44 kJ mol−1 and the kinetic equation was also deduced.