Carbon nanotubes(CNTs) have shown as unique nanoreactors to tune the catalytic activity of confined nano-catalysts. Here we report that the catalytic performance of molybdenum carbide nanoparticles(MoC_x NPs) for the ...Carbon nanotubes(CNTs) have shown as unique nanoreactors to tune the catalytic activity of confined nano-catalysts. Here we report that the catalytic performance of molybdenum carbide nanoparticles(MoC_x NPs) for the hydrogen evolution reaction(HER) process can be enhanced by encapsulation within single-walled carbon nanotubes(SWNTs) with a diameter of 1–2 nm. The catalyst with MoC_x NPs located on the interior surface of SWNTs(MoCx@SWNTs) exhibits a lower onset over-potential and a smaller Tafel slope than the one with MoC_x NPs attached on the exterior surface(MoCx/SWNTs). This is likely attributed to the much smaller particle size and the more reduced states of the confined MoC_x NPs, as well as the larger specific surface area of MoCx@SWNTs compared with Mo Cx/SWNTs. In addition, the electronic structure of the confined MoC_x NPs might be modified by the confinement effects of SWNTs, and hence the adsorption free energy of H atoms on the confined MoC_x NPs, which could also contribute to their higher performance. These results suggest that the SWNTs can be further explored for constructing novel catalysts with beneficial catalytic performance.展开更多
We present a facile and versatile method for introducing various non-precious metal nanoparticles （NPs） in small nanotubes, such as single-walled carbon nanotubes （SWNTs）, including 3d-metals （V, Mn, Fe and Co）,...We present a facile and versatile method for introducing various non-precious metal nanoparticles （NPs） in small nanotubes, such as single-walled carbon nanotubes （SWNTs）, including 3d-metals （V, Mn, Fe and Co）, 4d-metals （Mo）, and 5d-metals （W）. This is realized by oxidizing encapsulated cycloalkene metal carbonyl complexes below their sublimation temperatures. This novel technique is significant because it avoids the diffusion and deposition of metal species on the outer walls of nanotubes, which has been challenging to achieve using the conventional filling methods. High-resolution transmission electron microscopy （HRTEM）, high angle annular dark field scanning transmission electron microscopy （HAADF-STEM）, energy-dispersive X-ray spectroscopy （EDX）, Raman, and X-ray photoelectron spectroscopy （XPS） analyses revealed high filling efficiencies （〉 95% SWNTs filled with metal NPs）. This method also provides a unique approach to fabricate highly dispersed and uniform SWNT-metal nanoparficle encapsulates with lower valence states, which are often not stable in the bulk.展开更多
基金financially supported by the National Natural Science Foundation of China (No. 21425312, 21688102, 21621063, and 21573224)
文摘Carbon nanotubes(CNTs) have shown as unique nanoreactors to tune the catalytic activity of confined nano-catalysts. Here we report that the catalytic performance of molybdenum carbide nanoparticles(MoC_x NPs) for the hydrogen evolution reaction(HER) process can be enhanced by encapsulation within single-walled carbon nanotubes(SWNTs) with a diameter of 1–2 nm. The catalyst with MoC_x NPs located on the interior surface of SWNTs(MoCx@SWNTs) exhibits a lower onset over-potential and a smaller Tafel slope than the one with MoC_x NPs attached on the exterior surface(MoCx/SWNTs). This is likely attributed to the much smaller particle size and the more reduced states of the confined MoC_x NPs, as well as the larger specific surface area of MoCx@SWNTs compared with Mo Cx/SWNTs. In addition, the electronic structure of the confined MoC_x NPs might be modified by the confinement effects of SWNTs, and hence the adsorption free energy of H atoms on the confined MoC_x NPs, which could also contribute to their higher performance. These results suggest that the SWNTs can be further explored for constructing novel catalysts with beneficial catalytic performance.
文摘We present a facile and versatile method for introducing various non-precious metal nanoparticles （NPs） in small nanotubes, such as single-walled carbon nanotubes （SWNTs）, including 3d-metals （V, Mn, Fe and Co）, 4d-metals （Mo）, and 5d-metals （W）. This is realized by oxidizing encapsulated cycloalkene metal carbonyl complexes below their sublimation temperatures. This novel technique is significant because it avoids the diffusion and deposition of metal species on the outer walls of nanotubes, which has been challenging to achieve using the conventional filling methods. High-resolution transmission electron microscopy （HRTEM）, high angle annular dark field scanning transmission electron microscopy （HAADF-STEM）, energy-dispersive X-ray spectroscopy （EDX）, Raman, and X-ray photoelectron spectroscopy （XPS） analyses revealed high filling efficiencies （〉 95% SWNTs filled with metal NPs）. This method also provides a unique approach to fabricate highly dispersed and uniform SWNT-metal nanoparficle encapsulates with lower valence states, which are often not stable in the bulk.
