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Interfacial and Alloying Effects on Activation of Ethanol from First-Principles
journal contribution
posted on 2017-02-24, 00:00 authored by Wei An, Yong Men, Jinguo Wang, Ping LiuWe
present a first-principles density-functional theory study of
ethanol activation at oxide/Rh(111) interface and the alloying effect
on mitigating carbon deposition, which are essential to direct ethanol
fuel cell (DEFC) anode reaction and steam reforming of ethanol (SRE)
reaction. Our calculated results show that charge can transfer from
Rh(111) substrate to MOx chain (e.g.,
MoO3 and MnO2), or from MOx chain (e.g., MgO, SnO2, ZrO2, and TiO2) to Rh(111) substrate. The OH-binding strength is increased
exponentially with Mδ+ charge ranging from 1.4 to
2.2, which renders MnO2/Rh(111) and MgO/Rh(111) interfaces
weaker OH-binding, and thereby enhanced oxidizing functionality of
OH* for promoting ethanol oxidation reaction (EOR) at DEFC anode.
For efficient C–C bond breaking, a large number of Rh ensemble
sizes are critically needed at the interface of MOx/Rh(111). We found that Rh1Au3 near surface
alloy has the weakest C* and CO* binding, followed by Rh1Cu3 and Rh1Pd3 near surface alloys,
while Rh1Ir3 and Rh1Ru3 surface alloys have C* and CO* binding strength similar to that
of pure Rh metal. The general implication of this study is that by
engineering alloyed structure of weakened C* and CO* binding complemented
with metal oxides of weakened OH-binding, high-performance DEFC anode
or SRE catalysts can be identified.