Intermetallic Alloys as
CO Electroreduction CatalystsRole
of Isolated Active Sites
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Abstract
One of the main challenges associated
with the electrochemical
CO or CO<sub>2</sub> reduction is poor selectivity toward energetically
rich products. In order to promote selectivity toward hydrocarbons
and alcohols, most notably, the hydrogen evolution reaction (HER)
should be suppressed. To achieve this goal, we studied intermetallic
compounds consisting of transition metal (TM) elements that can reduce
CO (Ru, Co, Rh, Ir, Ni, Pd, Pt, and Cu) separated by TM and post transition
metal elements (Ag, Au, Cd, Zn, Hg, In, Sn, Pb, Sb, and Bi) that are
very poor HER catalysts. In total, 34 different stable binary bulk
alloys forming from these elements have been investigated using density
functional theory calculations. The electronic and geometric properties
of the catalyst surface can be tuned by varying the size of the active
centers and the elements forming them. We have identified six different
potentially selective intermetallic surfaces on which CO can be reduced
to methanol at potentials comparable to or even slightly positive
than those for CO/CO<sub>2</sub> reduction to methane on Cu. Common
features shared by most of the selective alloys are single TM sites.
The role of single sites is to block parasitic HER and thereby promote
CO reduction