cs400344r_si_001.pdf (459.53 kB)
A Water-Promoted Mechanism of Alcohol Oxidation on a Au(111) Surface: Understanding the Catalytic Behavior of Bulk Gold
journal contribution
posted on 2013-08-02, 00:00 authored by Chun-Ran Chang, Xiao-Feng Yang, Bo Long, Jun LiTo
understand the catalytic mechanism of alcohol oxidation with
molecular oxygen on bulk metallic gold catalysts, we have systematically
studied the oxidative dehydrogenation of methanol on Au(111) using
density functional theory. It is found that molecular oxygen can be
activated via a hydroperoxyl (OOH) intermediate produced by abstracting
a hydrogen atom from co-adsorbed methanol or water. Interestingly,
extra water molecules significantly promote the hydrogen-transfer
reactions between CH3OH···O2 and
H2O···O2 co-adsorbates, lowering
the activation barrier of OOH formation from ∼0.90 to ∼0.45
eV. The formed OOH intermediate either directly reacts with methanol
to produce formaldehyde or dissociates into adsorbed atomic oxygen
and hydroxyl. Further calculations demonstrate that the oxidative
dehydrogenation of methanol by OOH, atomic oxygen, and hydroxyl is
extremely facile with low barriers between 0.06 and 0.30 eV. These
results provide an explanation for the activation mechanism of molecular
oxygen on bulk gold and reveal a possible pathway for alcohol oxidation
with dioxygen.