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H2O dissociation on step Ni(211) surface: Mode selectivity under vibrational adiabaticity

Authors : Sudipta Roy, Nayanthara K. J. and Ashwani K. Tiwari*



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Abstract

Dissociation of water molecule on metal surface has been receiving extensive attention due to its industrial importance. Water adsorption and dissociation on step Ni(211) surface is studied from first-principle calculations and slab model. Effect of surface temperature and molecule-phonon coupling is investigated by including lattice motion calculation using sudden model and it has been found that increasing temperature of metal surface results in enhancement of catalytic activity of the surface toward water dissociation. Dynamics study of this reaction is investigated using Reaction Path Hamiltonian method. 1-D PES is constructed by taking into account all 9 molecular degrees of freedom. Normal mode calculation of all the molecular geometries of water molecule along the whole reaction path is calculated and it shows that symmetric and bending mode exhibit significant mode softening near the transition state, asymmetric mode does not exhibit any change of frequency along the whole reaction path. Under adiabatic approximation order of reaction probability for different vibrational normal modes is symmetric > bending > asymmetric > ground state.

 

Keyword

Water dissociation, heterogeneous catalysts, step surfaces, mode selectivity