Deposition
of platinum monolayers on Au substrate (denoted as Au@Pt<sub>ML</sub>) has been shown an efficient catalyst design strategy for
the electrocatalysis of alcohol oxidation due to presumed 100% utilization
of Pt atoms and substrate-enhanced catalytic activities. However,
the atomic structure and stability of Pt (sub)monolayers on realistic
nanoparticulate Au surface still remains elusive. Here, we reveal
coverage-dependent atomic structures and electrocatalytic stabilities
of Pt submonolayers (sML) on Au nanoparticles for methanol oxidation
reaction (MOR) by using high-resolution transmission electron microscopy
combined with energy dispersive X-ray spectrum imaging and electrochemical
techniques. At lower Pt coverages, the Pt<sub>sML</sub> more resembled
monatomic-thick layers, whereas higher Pt coverages above 0.5 ML resulted
in 3D subnanometer Pt nanoclusters leading to lower Pt utilization
efficiencies. Moreover, the Au@Pt<sub>sML</sub> catalysts with Pt
coverage below 0.5 ML showed higher structural and electrocatalytic
stability during MOR electrocatalysis. As a result, increasing the
Pt coverage beyond 0.5 ML brought in no obvious gain in the overall
catalytic performance. Our results suggest that the Au@Pt<sub>0.5 ML</sub> catalyst appears to be a more reasonable MOR catalyst than previously
reported Au@Pt<sub>1.0 ML</sub> catalyst, providing more rational
catalyst design for achieving high Pt utilization efficiency and high
catalytic performance
