Quantum Dynamics of Water Dissociation on Copper-Nickel Bimetallic Alloy Surface

Ray, Dhiman (2018) Quantum Dynamics of Water Dissociation on Copper-Nickel Bimetallic Alloy Surface. Masters thesis, Indian Institute of Science Education and Research Kolkata.

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Abstract

Copper-Nickel bimetallic alloys are emergent heterogeneous catalysts for water dissociation which is the rate determining step of industrially important Water Gas Shift (WGS) reaction. Yet, the detailed quantum dynamics studies of water-surface scattering in literature are limited to pure metal surfaces. We performed three dimensional wave-packet dynamics study of water dissociation on Cu-Ni alloy surfaces, using a pseudo diatomic model of water on a London-Eyring-Polanyi-Sato (LEPS) potential energy surface in order to study the effect of initial vibration, rotation and orientation of water molecule on reactivity. For all the chosen surfaces reactivity increases significantly with vibrational excitation. In general, for lower vibrational states the reactivity increases with increasing rotational excitation but it decreases in higher vibrational states. Molecular orientation strongly affects reactivity by helping the molecule to align along the reaction path at higher vibrational states. For different alloys, the reaction probability follows the trend of barrier heights and the surfaces having all Ni atoms in the uppermost layer are much more reactive than the ones with Cu atoms. Hence the nature of the alloy surface and initial quantum state of the incoming molecule significantly in uence the reactivity in surface catalyzed water dissociation.

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