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Chapter 5 139
it is hard to distinguish these two possibility. To note, no Cl Kα peak could be observed in
the EDX spectrum of the Cu/Pd-BTC_4 (Figures 5.17), suggesting absence (at least in high
concentration) of Cl - or PdCl2.
Figure 5.17. EDX spectrum of the sample Cu/Pd-btc_4 with the assignments of Cl Kα and Cl Kβ
(green lines).
Deconvoluted XP spectra from the Pd 3d region scan has been gathered for the sample
Cu/Pd-BTC_4 (Figure 5.18). In addition to the Pd 3d doublet (Pd 3d3/2 and Pd 3d5/2) of
Pd 2+ at 343.6 and 338.4 eV as well as 342.4 and 337.2 eV (Table 5.5), [288-289] another
doublet appears at 340.9 and 335.7 eV, which can be attributed to Pd 0 in metallic
palladium. Compared with Cu/Pd-BTC_1-3, this sample reveals dominant Pd 0 than in
case of Cu/Pd-BTC_1-3. The concentration of Pd 0 is determined to amount to 70 %.
Likewise, in Cu/Pd-BTC_1-3, only the O 1s peak at 531.8 eV stemming from COO- has
been revealed. Hence, the presence of PdO can be ruled out due to the absence of
corresponding O 1s peak at about 530 eV. Moreover, the peak of Cl 2p in the survey scan
of Cu/Pd-BTC_4 cannot be observed (Figure 5.19), which together with SEM result
proves that the Pd 2+ in the solid is attributed from Pd 2+ /M 2+ -node in the framework rather
than Pd 2+ -precursor or PdO loading on the framework.