jp8b07887_si_001.pdf (1.26 MB)
Graphene-Supported Monometallic and Bimetallic Dimers for Electrochemical CO2 Reduction
journal contribution
posted on 2018-11-26, 00:00 authored by Haiying He, Christopher Morrissey, Larry A. Curtiss, Peter ZapolBimetallic
catalysts are attractive alternatives to extend the
parameter space that can be tuned for support interactions and catalytic
performance. In this study, we have investigated the smallest bimetallic
catalystsdimerssupported on defective graphene for
the electrochemical reduction of CO2 to CH4 based
on a first-principles approach and the computational hydrogen electrode
model. The monometallic and bimetallic dimers formed from Group 10
(Ni, Pd, Pt) and group 11 (Cu, Ag, Au) elements are characterized
by a positively charged anchoring atom occupying the vacancy site
of graphene and a neutral or slightly negatively charged antenna atom
sticking out from the graphene surface. The strong selective binding
of these dimers ensures their high stability. Possible rate-limiting
steps are identified from the full reaction pathways to generate CH4. Overall, Pt2, AgNi, Pd2, and AgPt
are the best candidates with the lowest overpotential values of 0.37,
0.69, 0.69, and 0.76 V, respectively. It is found that the alloy effect
and the interaction with support help to optimize the property. These
metallic dimers, however, retain nonmonotonous property relationships
that give opportunity to go beyond scaling behavior and look for a
few atom catalysts that have unique properties to reduce rate-limiting
potentials and improve the catalytic performance.