TY - JOUR
T1 - Interplay of ligand and strain effects in CO adsorption on bimetallic Cu/M (M = Ni, Ir, Pd, and Pt) catalysts from first-principles
T2 - Effect of different facets on catalysis
AU - Jo, Deok Yeon
AU - Lee, Min Woo
AU - Kim, Chang Hwan
AU - Choung, Jin Woo
AU - Ham, Hyung Chul
AU - Lee, Kwan Young
N1 - Funding Information:
This work was supported by the National Research Foundation of Korea (NRF) Grant funded by the Korean Government(MSIP) ( NRF-2016R1A5A1009592 ).
Publisher Copyright:
© 2019 Elsevier B.V.
PY - 2021/1/1
Y1 - 2021/1/1
N2 - Cu-based catalysts have been variously used in the water gas shift reaction (WGSR) and methanol synthesis, both of which use carbon monoxide as a common reactant. According to the Bell–Evans–Polanyi principle, CO adsorption energies (Eads,CO) directly affect the activation energies for CO hydrogenation. Thus, the understanding of the relationship between Eads,CO and the chemical properties of the catalytic surface is fundamental to catalyst design. In particular, recent studies have shown that effective catalysts can be developed by controlling the exposed facets or forming alloys with other transition metal to enhance the mechanical and electronic characteristics. In bimetallic catalysts, two types of chemical effects are known to determine the adsorption energies: one is the “strain” effect caused by lattice mismatch and the other is the “ligand” effect, generated by the change in orbital electrons. We conducted calculations on Cu/M(100), (111), and (211) surfaces (M = Ni, Ir, Pd and Pt) by using spin-polarized density functional theory (DFT) calculations to find the dominant factor, as well as trends, affecting CO adsorption. Our calculations suggest the ligand effect is the dominant contribution to Eads,CO, regardless of the type of facets. We also determined that the ligand contribution is caused by the loss of electrons from the surface Cu atoms. As a result, a proportional correlation between ligand contribution and electron charge transfer was observed. On investigating the strain effect on the (111) facet, we found that the results are consistent with d-band theory, while the Eads,CO on (100) and (211) facets showed the opposite trend.
AB - Cu-based catalysts have been variously used in the water gas shift reaction (WGSR) and methanol synthesis, both of which use carbon monoxide as a common reactant. According to the Bell–Evans–Polanyi principle, CO adsorption energies (Eads,CO) directly affect the activation energies for CO hydrogenation. Thus, the understanding of the relationship between Eads,CO and the chemical properties of the catalytic surface is fundamental to catalyst design. In particular, recent studies have shown that effective catalysts can be developed by controlling the exposed facets or forming alloys with other transition metal to enhance the mechanical and electronic characteristics. In bimetallic catalysts, two types of chemical effects are known to determine the adsorption energies: one is the “strain” effect caused by lattice mismatch and the other is the “ligand” effect, generated by the change in orbital electrons. We conducted calculations on Cu/M(100), (111), and (211) surfaces (M = Ni, Ir, Pd and Pt) by using spin-polarized density functional theory (DFT) calculations to find the dominant factor, as well as trends, affecting CO adsorption. Our calculations suggest the ligand effect is the dominant contribution to Eads,CO, regardless of the type of facets. We also determined that the ligand contribution is caused by the loss of electrons from the surface Cu atoms. As a result, a proportional correlation between ligand contribution and electron charge transfer was observed. On investigating the strain effect on the (111) facet, we found that the results are consistent with d-band theory, while the Eads,CO on (100) and (211) facets showed the opposite trend.
KW - (100)facet,(111)facet,(211)facet
KW - CO adsorption
KW - Coordination number vs Bader charge vs ligand contribution
KW - Cu/M alloy (M=Ni,Ir,Pd,Pt)
KW - Ligand effect
KW - Strain effect
UR - http://www.scopus.com/inward/record.url?scp=85066415548&partnerID=8YFLogxK
U2 - 10.1016/j.cattod.2019.05.031
DO - 10.1016/j.cattod.2019.05.031
M3 - Review article
AN - SCOPUS:85066415548
SN - 0920-5861
VL - 359
SP - 57
EP - 64
JO - Catalysis Today
JF - Catalysis Today
ER -