Graphene-supported Cu11 nanocluster as a candidate catalyst for the selective hydrogenation of acetylene: A density functional study

Highlights: • Dissociative adsorption of hydrogen was determined on the Cu₁₁ nanocluster. • E_ad of C₂H₂ on Cu₁₁2H complex is higher than the E_ad of C₂H₄. • Cu₁₁ nanocluster can be used as catalyst for the selective hydrogenation of C₂H₂. In this paper, by the density functional theory (DFT) calculations we show that the copper nanocluster can be used as catalyst for the hydrogenation of acetylene and ethylene. Since the nature of dissociation of hydrogen molecule on the copper nanocluster is the governing step for the hydrogenation reaction, the adsorption and complete dissociation of H₂ on the Cu₁₁ nanocluster is investigated at PBE-G/DNP-ECP level of theory. The results show that H₂ is adsorbed dissociatively on the Cu₁₁ nanocluster. To examine the activity of copper nanocluster as a catalyst for the hydrogenation reaction, the hydrogenations of acetylene and ethylene are investigated on the free Cu₁₁ nanocluster, due to its highest adsorption energies for hydrogen, acetylene and ethylene adsorptions. In the presence of the Cu₁₁ nanocluster as a catalyst, acetylene and ethylene can be hydrogenated to ethylene and ethane, respectively. These reactions are exothermic with the total reaction energies of −247.61 and −174.01 kJ/mol for hydrogenation of acetylene and ethylene, respectively. One of the interesting features of this catalyst is that the energy of acetylene adsorption on Cu₁₁2H complex is higher than the energy of ethylene adsorption. It seems that Cu₁₁ nanocluster can be used as catalyst for the selective hydrogenation of acetylene. Also, we choose graphene as a support for copper nanocluster and the hydrogenation of acetylene and ethylene on graphene-supported Cu₁₁ nanocluster are investigated. Based on our DFT calculations, we suggest graphene-supported Cu₁₁ nanoclusters as candidates with good activity and selectivity for the acetylene hydrogenation reaction.