Journal
JOURNAL OF PHYSICAL CHEMISTRY C
Volume 126, Issue 42, Pages 17913-17922Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.jpcc.2c04720
Keywords
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Funding
- National Natural Science Foundation of China
- [22172151]
- [21972131]
- [21832004]
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Nanoparticles with a Au core and a Pt shell (Au@Pt-x ML) exhibited superior activity towards the oxygen reduction reaction (ORR). The extent of enhancement of the ORR activity and the adsorption strength of oxygen-containing species increased with decreasing Pt shell thickness. SERS results showed different spectral characteristics of adsorbed CO compared to pc-Pt.
Nanoparticles with a 55 nm Au core and a few monolayers of Pt shell (denoted as Au@Pt-x ML, x = 1-4) are found to have superior activity toward the oxygen reduction reaction (ORR) compared to commercial Pt nanoparticles and polycrystalline Pt (pc-Pt) electrodes in 0.1 M HClO4. The half-wave potential for ORR at Au@Pt-1 ML is ca. 20 mV positively shifted. With the decrease of the Pt shell thickness from 4 to 1 monolayer, both the extent of enhancement of the ORR activity and the adsorption strength of oxygen-containing species increase; the latter is confirmed by results from surface-enhanced Raman spectroscopy (SERS) and X-ray photon emission spectroscopy (XPS). Furthermore, SERS results also reveal that adsorbed CO on such catalysts displays a blue shift in Pt-CO and a red shift in C-O stretching frequencies compared to that at pc-Pt under otherwise identical conditions. Positive double layer effects induced by diminishing surface charge density, which leads to the less rigid first layer of water, are suggested to be the origin of the superior ORR performance of Au@Pt-x ML to that of commercial Pt/C catalysts.
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