Heterolytic dissociative adsorption state of dihydrogen favored by interfacial defects

Highlights: • Dihydrogen splitting on interfacially defected MgO/Mo was investigated systematically. • Heterolytic fragmentation path shows very low activation barrier (0.398 eV). • The heterolytic dissociation state is much more favorable than homolytic one both energetically and kinetically. • The results provided evidence for enhancing the activity of insulating oxide by introducing interfacial defects. The atomic-scale insight into dihydrogen on MgO(001) surface deposited on molybdenum substrate with interfacial defects was investigated in detail by employing density functional methods Here we report novel dissociative adsorption behaviors of single hydrogen molecule on the usually inert oxide surfaces, with consideration of two types of dissociation schemes. The heterolytic dissociation state −Mg(H)-O(H)- of dihydrogen is impossible to obtain on neighboring O-Mg sites of perfect bulk MgO(001) terraces. Unusually, the hydrogen molecule can form heterolytic fragmentation states on metal supported MgO(001) films with very low activation barrier (0.398 eV), and the heterolytic dissociation state is much more favorable than homolytic dissociation state both energetically and kinetically in all cases. Electronic properties and bonding attribution of adsorbates and the oxide-metal hybrid structure are revealed by analyzing density of states, differential charge densities, orbital interaction and electron localization function. The characteristic changes to the property and activity of magnesia (001) can have potential application in catalytic reactions.