【摘 要】
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Step sites over terrace sites have been suggested to be the active sites in many catalytic reactions particularly bond-breaking of diatomic molecules.Aiming to provide further insight into the role of
【机 构】
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State Key Laboratory of Catalysis,Dalian Institute of Chemical Physics,Chinese Academy of Sciences,D
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Step sites over terrace sites have been suggested to be the active sites in many catalytic reactions particularly bond-breaking of diatomic molecules.Aiming to provide further insight into the role of step sites in multi-atomic molecules bond breaking reactions and its dependence on catalysts,we present here a systematic first-principles study of C=O bond scission of diatomic CO,multi-atomic HCO and CH3HCO on flat and stepped Co,Rh and Ir surfaces.We show that multi-atomic molecules exhibit distinct C=O scission activity as diatomic molecule regardless of metal catalysts considered: compared to the huge enhancement of step sites for CO with a barrier 0.81-1.29 eV lower than flat surfaces,the role of step sites for CH3CHO is substantially weakened with a barrier 0.11-0.27 eV higher than flat surfaces.The reason is change of adsorption configurations at flat surfaces and increase of Pauli repulsion at the congested stepped sites for multi-atomic molecules dissociation.
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