Different amounts of nickel were loaded on carbon nanotubes (CNTs) by an impregnation method and characterized by N2 adsorption/desorption isotherms, X-ray diffraction, X-ray photoelectron spectroscopy, H2 temperature-programmed reduction, H2 chemisorption, and transmission electron microscopy to study the porosity, the crystalline phases, the surface property, the reducibility property, the metallic Ni dispersion, and morphology. It was found that two types of Ni2+ species differing by the interaction with the CNTs support coexisted; the amount of free NiO was dominated by Ni content. More metallic Ni species could be thus obtained on the catalyst with higher Ni loading. Furthermore, the descriptor between the active phases property and the catalytic performances was established, which suggested that both the surface area and the state of Ni dispersion synergistically determined the catalytic reaction. The catalysts showed the good catalytic performances at a relative lower reaction temperature of 375 °C.

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With extra space, a carbon nanotube (CNT) could serve as an absorber of point defects, including helium interstitials, and outgas the accumulate helium via “nano-chimneys”. The radiation resistance of CNT/Fe has still not been fully understood. Herein, we investigated the influence of CNTs on low-energy helium irradiation resistance in CNT/Fe composites by molecular dynamic simulations. CNTs reduced the small and medium He clusters in the Fe matrix. When the incident energy of the He atoms was 300 eV, the He atoms aggregated at the outer surface of CNTs. CNTs postponed the formation of He bubbles. When the irradiation energy was higher than 600 eV, He atoms could penetrate the walls of CNTs and form clusters inside the single-walled CNTs or the space in double-walled CNTs—the latter presented better performance. The reduction of Frenkel pair point defects suggested the enhancement of radiation resistance by the presentation of CNTs. Our results might be useful for the material design of advanced steels for radiation resistance.