Ab Initio Molecular Dynamics Simulation of the Dissociation of Ethanol on a Nickel Cluster: Understanding the Initial Stage of Metal-Catalyzed Growth of Carbon Nanotubes

Abstract

The dissociation of ethanol molecules on a nickel cluster was investigated by ab initio molecular dynamics and nudged-elastic-band (NEB) simulations to discuss the initial stage of metal-catalyzed growth of carbon nanotubes via alcohol catalytic chemical vapor deposition. Both C− C and C−O bonds in ethanol molecules are dissociated on the nickel cluster, which is followed by the formation of various reaction products such as hydrogen atoms and molecules, carbon monoxide, oxygen atoms, water, ethylene, methane, and their fragments. Moreover, the NEB analysis revealed that the activation energy for C−H bond dissociation in the fragment molecules on the nickel cluster is just approximately one-eighth of the bond-dissociation energy of the corresponding C−H bond without the influence of the nickel cluster. This confirms that the nickel cluster acts as the activator of the dissociation process of carbon-source molecules by reducing the activation energy.

Reaction of ethylene molecules with a nickel cluster: <i>ab initio</i> molecular dynamics study

“…The inhibition of the dehydrogenation has been found in the case of ethanol molecules with the Ni cluster [30,31]. By removing the hydrogen atoms on the Ni cluster in the middle of the simulation, it has been confirmed that the adsorption and dehydrogenation of the ethanol molecules reoccurred.…”

Ab initio molecular dynamics simulation of ethanol decomposition on platinum cluster at initial stage of carbon nanotube growth

“…On the other hand, we have closely discussed the dissociation of carbon source molecules on various catalytic metals based on the ab initio MD simulation [29][30][31][32][33], which takes into account both the chemical reaction with the accuracy of the ab initio calculation and the dynamics of atoms simultaneously, in order to discuss the initial stage of the CNT growth. Up to now, we have revealed the bond dissociation mechanism of ethane [29] and ethylene [30] on a nickel (1 1 1) surface, that of ethanol [31,32] and ethylene [33] on a nickel cluster, and that of methane and derivative fragment molecules on a copper (1 1 1) surface [34].…”

Insights into ethanol decomposition over Pt: A DFT energy decomposition analysis for the reaction mechanism leading to C2H6 and CH4

“…The calculation of reaction mechanisms over solid catalysts normally employs a combination of plane wave basis set, pseudopotentials and periodic conditions [5,6,12,22,23]. This approach has the advantage of allowing the reaction to take place over a relatively large surface in an attempt to reproduce the real experimental conditions.…”

“…The formation of such byproducts is governed by the several reaction intermediaries and transition states, in such a way that a knowledge of how these species behave along the reaction path is crucial to understand and control their role. Additionally, decomposition of ethanol over metal catalysts is among the methods for the growth of carbon nanotubes [5].…”

“…In our approach, we opt for the use of a metal cluster instead of a periodic structure as found in most of the research conducted so far [5,6,12]. The reason for this is twofold.…”