Water dissociation on Ni(100), Ni(110), and Ni(111) surfaces: Reaction path approach to mode selectivity

Abstract

A comparative study of mode-selectivity of water dissociation on Ni(100), Ni(110), and Ni(111) surfaces is performed at the same level of theory using a fully quantum approach based on the reaction path Hamiltonian. Calculations show that the barrier to water dissociation on the Ni(110) surface is significantly lower compared to its close-packed counterparts. Transition states for this reaction on all three surfaces involve the elongation of one of the O-H bonds. A significant decrease in the symmetric stretching and bending mode frequencies near the transition state is observed in all three cases and in the vibrational adiabatic approximation, excitation of these softened modes results in a significant enhancement in reactivity. Inclusion of non-adiabatic couplings between modes results in the asymmetric stretching mode showing a similar enhancement of reactivity as the symmetric stretching mode. Dissociation probabilities calculated at a surface temperature of 300 K showed higher reactivity at lower collision energies compared to that of the static surface case, underlining the importance of lattice motion in enhancing reactivity. Mode selective behavior is similar on all the surfaces. Molecules with one-quantum of vibrational excitation in the symmetric stretch, at lower energies (up to ∼0.45 eV), are more reactive on Ni(110) than the Ni(100) and Ni(111) surfaces. However, the dissociation probabilities approach saturation on all the surfaces at higher incident energy values. Overall, Ni(110) is found to be highly reactive toward water dissociation among the low-index nickel surfaces owing to a low reaction barrier resulting from the openness and corrugation of the surface. These results show that the mode-selective behavior does not vary with different crystal facets of Ni qualitatively, but there is a significant quantitative effect.

HOD on Ni(111): Ab Initio molecular dynamics prediction of molecular beam experiments

“…c) Email: g.j.kroes@chem.leidenuniv.nl more and more degrees of freedom (DOFs) and details in the potential energy surface (PES). 3,4,[7][8][9][10][11]15,[17][18][19][20][21][22][23][24]26,30 The dissociation of water on metal surfaces is a late barrier process 3,4,15 which is greatly promoted by vibrational energy in the molecule, 3,4,20,21 and it exhibits large mode 9,10 and bond 19 specificity in agreement with Polanyi's rule. 31 This is also in agreement with results of the sudden vector projection (SVP) model 5,6 which predicts large couplings between the vibrational modes of the reactant and the reaction coordinate at the transition state.…”

Electrode kinetics of porous Ni-3YSZ cermet operated in fuel cell and electrolysis modes for solid oxide cell application

“…In complementarity with the EC simulations, physically-based modeling is an efficient tool to propose and check the relevance of reaction mechanisms. In this frame, several authors have studied the steam and hydrogen interaction with Ni/YSZ using Density Functional Theory (DFT) to determine the most energetically favorable configuration [44][45][46][47][48][49][50][51][52][53][54][55][56]. These theoretical investigations showed that the interaction of hydrogen with the Ni/YSZ system results in dissociative adsorption of H 2 on the Ni surface [44,49,50,54], whereas steam molecules can be adsorbed on both surfaces.…”

Computational approaches to dissociative chemisorption on metals: towards chemical accuracy

“…101,[143][144][145][146][147][148][149][150][151] Researchers are also starting to use meta-GGA (mGGA) DFs. 151,152 Goals of these calculations include validating models, 61,62,65,73,74,76,86,89,98,100,102,105,106,123,145,153 analyzing features of the reaction mechanism, 21,51,53,58,[64][65][66][69][70][71][72]75,77,[79][80][81][82]87,[90][91][92][93][94]…”