Ni nanoparticles encapsulated in the channel of titanate nanotubes: Efficient noble-metal-free catalysts for selective hydrogen generation from hydrous hydrazine

- Ni nanoparticles were encapsulated in the channel of titanate nanotubes (Ni@TNTs).
- Ni@TNTs exhibited good catalytic performance for H2 generation from N2H4·H2O.
- Enhanced catalytic activity was due to the small size and high dispersion of Ni NPs.
- The confinement of TNTs prevents Ni NPs from leaching or aggregation.

Ni nanoparticles were encapsulated in the channel of titanate nanotubes (TNTs) by the capillary forces under ultrasonic treatment (Ni@TNTs). The structure and properties of the catalyst were studied by scanning electronic microscopy (SEM), transmission electron microscopy (TEM), Energy dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H2-temperature programmed reduction (H2-TPR), CO chemisorption and N2 adsorption-desorption, respectively. The TEM, EDX and N2 adsorption-desorption results demonstrated that Ni nanoparticles (NPs) were encapsulated in the channel of TNTs successfully. The results of XRD, H2-TPR and XPS indicated a strong metal-support interaction between Ni NPs and TNTs. Ni@TNTs exhibited a good catalytic performance for the decomposition of hydrous hydrazine which was due to the small nanoparticle size and high dispersion of Ni NPs after encapsulation in the channel of TNTs. The catalyst could be recycled six times without significant loss in catalytic activity, which was attributed that the confinement of TNTs prevents Ni NPs from leaching or aggregation. The design strategy for NPs confined in nanotubes may have potential applications in many heterogeneous reactions.

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