Fig. 4 | Nature Communications

Fig. 4

From: Boosting hot electron flux and catalytic activity at metal–oxide interfaces of PtCo bimetallic nanoparticles

Fig. 4

Formation of CoO on PtCo bimetallic NPs. a Co 2p XPS spectra showing the oxidation states of the Co in the Pt x Co y bimetallic NPs before and after H2 oxidation. b Relative ratio of CoO in the Pt x Co y bimetallic NPs estimated using the peak area of Co2+. Error bars are ± sd. Sequential in situ TEM images of the Pt3Co1 NP taken at c 0 and d 36 s during oxidization at 125 °C in 0.5 mbar of O2 gas. As denoted by the red arrows, additional Co atoms segregated on the Pt3Co1 NP surface. The difference in lattice spacing between the top-most layer and the inner portion is clearly shown in the enlargement region denoted by the white rectangle. Scale bars are 5 nm (left) and 2 nm (right)

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