Ab Initio Molecular Dynamics Simulation of Water Transport through Short Carbon Nanotubes

Abstract

Water transport through short single-walled (6, 6) carbon nanotubes (CNTs) was investigated with ab initio molecular dynamics (AIMD) simulation at different temperatures. The water molecules under extreme confinement present a one-dimensional jagged pattern owing to hydrogen bonding, with the near-perfect alignment of the dipole orientations. CNTs ending with dangling bonds can promote water dissociation near the entrance and the occurrence of dipole flipping along the water wire at high temperatures, accompanied by the formation of D defects and L defects in the hydrogen-bond network. In contrast, dissociation of water molecules rarely takes place if the dangling bonds at the ends of the CNTs are terminated with H atoms. Angular jumps of water molecules are commonplace inside the narrow CNTs, implying a low-energy barrier for hydrogen-bond exchange among water molecules in narrow CNTs. The simulation results demonstrate the high activity of dangling bonds at the ends of short CNTs, accompanying passivation processes and their profound impact on water structure and transport, which is important for diverse technological applications.

Design of MoS2 edge-anchored single-atom catalysts for propane dehydrogenation driven by DFT and microkinetic modeling

“…9 We further examined the PDH process assisted by neighboring unsaturated edge-Mo atoms within the motif region of the TM 1 -S 4 /edge catalyst, since the dangling bond on the edge-Mo atom normally exhibits high reactivity. [56][57][58] As expected, the energy barrier of a-C dehydrogenation is lowered to 0.76 eV when assisted by the unsaturated edge-Mo atom (TS3 in Fig. 3b).…”

“…5a, the TM 1 -S 4 /edge (TM = Ru, Os) catalysts contain relatively abundant single d electrons among the six candidates, and the resulting unsaturated bonds give the high activities. 57–59,62…”

“…5a, the TM 1 -S 4 /edge (TM = Ru, Os) catalysts contain relatively abundant single d electrons among the six candidates, and the resulting unsaturated bonds give the high activities. [57][58][59]62 Given the high activities of the TM 1 -S 4 /edge (TM = Ru, Os) catalysts, we further assess the thermodynamic stability of these six screened TM 1 -S 4 /edge (TM = Sc, Pt, Rh, Ir, Os, and Ru) SACs by using AIMD simulations. The results show that the doped TM atoms on these six TM 1 -S 4 /edge SACs always remain stable rather than collapsing at 900 K (Fig.…”

Uniqueness of Nanoscale Confinement for Fast Water Transport: Effect of Nanotube Diameter and Hydrophobicity

“…Presence of the dangling bonds might affect the structure and dynamics of confined water molecules as shown by the studies of Corry, Hughes et al and Sahu et al . The AIMD studies of Liu et al demonstrated that the presence of dangling bonds can promote water dissociation near the entrance, however, it was not possible to capture the same in present classical MD simulations. The brief discussion over impact of dangling bonds has been included in Supporting Information as Text S4.…”

Point defect-mediated hot carrier relaxation dynamics of lead-free FASnI3 perovskites

“…S1 of the ESI, † suggesting enough thermal stability. 41 As evident from Fig. S2 and S3 in the ESI, † the pristine and corresponding perovskite systems are found to be significantly stable in the microcanonical ensemble.…”