| Summary: | In this work, the H<sub>2</sub> dissociation and acetylene hydrogenation on Cu doped CeO<sub>2</sub>(111) were studied using density functional theory calculations. The results indicated that Cu doping promotes the formation of oxygen vacancy (O<sub>v</sub>) which creates Cu/O and Ce/O frustrated Lewis pairs (FLPs). With the help of Cu/O FLP, H<sub>2</sub> dissociation can firstly proceed via a heterolytic mechanism to produce Cu-H and O-H by overcoming a barrier of 0.40 eV. The H on Cu can facilely migrate to a nearby oxygen to form another O-H species with a barrier of 0.43 eV. The rate-determining barrier is lower than that for homolytic dissociation of H<sub>2</sub> which produces two O-H species. C<sub>2</sub>H<sub>2</sub> hydrogenation can proceed with a rate-determining barrier of 1.00 eV at the presence of Cu-H and O-H species., While C<sub>2</sub>H<sub>2</sub> can be catalyzed by two O-H groups with a rate-determining barrier of 1.06 eV, which is significantly lower than that (2.86 eV) of C<sub>2</sub>H<sub>2</sub> hydrogenated by O-H groups on the bare CeO<sub>2</sub>(111), showing the high activity of Cu doped CeO<sub>2</sub>(111) for acetylene hydrogenation. In addition, the rate-determining barrier of C<sub>2</sub>H<sub>4</sub> further hydrogenated by two O-H groups is 1.53 eV, much higher than its desorption energy (0.72 eV), suggesting the high selectivity of Cu doped CeO<sub>2</sub>(111) for C<sub>2</sub>H<sub>2</sub> partial hydrogenation. This provides new insights to develop effective hydrogenation catalysts based on metal oxide.
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