Theoretical Study of Hydrogen Adsorption and Diffusion on TiN(100) Surface

Abstract

TiN bulk and surface energy and hydrogen atom adsorption at three different sites have been studied using density functional theory (DFT) with local and non-local exchange-correlation functionals. Calculations of surface energies confirm the experimental findings that the (100) surface has the lowest and the (111) surface the highest surface energy, respectively. Adsorption of H on top of Ti atom is more favorable by 1.7 kcal/mol than on top of N atom and is in agreement with plane-wave calculations and experimental results available in the literature. We also discuss the surface diffusion scenario of H on the (100) surface of TiN.

Nature of Hydrogen Interaction and Saturation on Small Titanium Clusters

“…There too, the hydrogen molecule was dissociated only when it was directly above a palladium atom on the surface. This seems to indicate that the main driving force for dissociation is due to Pauli repulsion, which is in consonance with earlier observations. ,, After dissociation, the two hydrogen atoms travel in opposite directions and the equilibrium geometry results from optimization of one of the structures obtained around 50 fs. When the simulation was carried out for long periods of time (∼150 fs), the adsorbed hydrogen atoms eventually coalesce, form a hydrogen molecule, and are ejected away from the titanium cluster.…”

“…Although the charges on the titanium atom are affected by its interaction with the hydrogen molecule, it would be more interesting to examine the evolution of the charges on the hydrogen molecule as it approaches the titanium cluster. We employ the AIM method to monitor the charge densities of the entire system at different time steps.…”

“…Harris and Andersson have argued that the empty d states of the transition metal enables the formation of M−H bond without the strong involvement of the repulsive s-type metal orbitals . Latter work, however, indicates that the above theory is only valid at long distances and activation energies do appear for interactions dominated by covalent effects. , …”

Oxygen Defects Containing TiN Films for the Hydrogen Evolution Reaction: A Robust Thin Film Electrocatalyst With Outstanding Performance

“…[24,25] The values obtained on TiN (111) range from 0.60 to 3.11 eV for N-termination and from 1.93 to 3.59 eV for Ti termination [24]. A slightly different values were obtained by Siodmiak et al on TiN (100) surface [25]. Overall, the adsorption energies are considered to be moderate, albeit larger than on Pt.…”

“…Further, it has been shown using density functional theory that hydrogen adsorbs on TiN with the adsorption energy being dependent on termination (N or Ti) and adsorption sites. [24,25] The values obtained on TiN (111) range from 0.60 to 3.11 eV for N-termination and from 1.93 to 3.59 eV for Ti termination [24]. A slightly different values were obtained by Siodmiak et al on TiN (100) surface [25].…”