N-Sites for Anchoring of Noble Metal Atoms Active in Formic Acid Decomposition
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The use of N-doped instead of N-free carbon support for deposition of noble metal
atoms, such as Pt, Pd, and Ru, results in an enhancement of catalytic activity of
metal in the process of hydrogen production from formic acid. We consider a set of Ndoped
graphene models with single or two N atoms substituted from carbon atoms at
zigzag or armchair graphene edge, vacancy boundary, and in the center. The interaction
energies of noble metals with N-sites in graphene network were calculated
within density functional theory (DFT) at the pbe/LACVP level. Independently
on the type of the N-site the following trend of metal atoms Ru>Pt>Pd occurred
according to the strength of the interaction. By comparing this dependence with
the catalytic activity of corresponding metals, we conclude that the interaction of
metal with the support should be not too strong as for Ru and not too weak as for
Pd. The most active site of Pt and Pd for the formic acid decomposition is a single
atom attached to a couple of pyridininc N at the graphene edge. Atomic distribution
of metals over N-doped carbon support was confirmed by an aberration-corrected
HAADF/STEM study.