Hydrogen evolution from catalytic hydrolysis of NaBH4: Comparative study between the catalytic activity of TiO2 nanotubes with various arrangements

Nowadays, a lot of efforts have been applied to find an appropriate catalyst for generating hydrogen from NaBH4. Hence in the current study, various nanostructures of TiO2 were employed to obtain an insight into how the different support catalysts effect on the hydrolysis rate of NaBH4. For this aim, disordered filaments (DF-NTs) and ordered free-standing TiO2 nanotubes (FS-NTs) were fabricated via hydrothermal and chemical-assisted two-step anodization methods, respectively. The physical and chemical features of catalysts were analyzed using FESEM, XRD, FTIR and BET analysis, respectively. The results showed, TiO2 itself has catalytic activity and the H2 generation rate by FS-NTs was 1.67 and 5.26 times more than the generation rate by DF-NTs and spherical TiO2 nanoparticles, respectively. This premier catalytic behavior of FS-NTs can be ascribed to its high surface area (112.77 m2/g) and ordered arrangement of the nanotubes which allows reagents to be easily transferred to the active sites. The kinetic study revealed that hydrolysis of NaBH4 using the catalyst of FS-TNs is a first-order reaction regarding catalyst amount, while it is a zero-order reaction regarding the NaBH4 level. Moreover, the reusability results exhibited that FS-TNs has good durability and performance even up to the Fifth run.