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130 Chapter 5<br />
5.3 Compositional characterization and sorption properties of the prepared<br />
Cu/Pd-BTC_1-3<br />
AAS analysis of the activated Cu/Pd-BTC_1-3 solids confirms quantitative incorporation<br />
of palladium. Thus, the Pd-contents and Pd : Cu ratios in the final Cu/Pd-BTC_1-3 samples<br />
remain almost unchanged with respect to the taken feeding ratios of the metal-precursors<br />
(Table 5.2). Further, SEM-EDX elemental mapping demonstrates quite homogeneous<br />
Cu/Pd distribution within obtained Cu/Pd-BTC solids (Figure 5.7).<br />
Table 5.2. Feeding and observed contents of Pd in respect to the total metal amount in Pd@[Cu 3-<br />
xPd x (BTC) 2 ] n (Cu/Pd-BTC_1-3). The incorporation Pd-percentages were calculated based on the<br />
AAS results.<br />
Sample feeding (molar%) obtained (molar%) obtained wt%<br />
Cu/Pd-BTC_1 10 9 3.9<br />
Cu/Pd-BTC_2 15 14 6.2<br />
Cu/Pd-BTC_3 20 20 9.2<br />
Figure 5.7. EDX elemental mapping of the Cu/Pd-BTC_3 solid (red – Cu; green – Pd).<br />
Incorporation of Pd 2+ into the framework as well as the Pd 0 NPs loading has been<br />
subsequently corroborated by high-resolution XPS. Figure 5.8 shows the Pd 3d core-level<br />
spectra of the Cu/Pd-BTC_1 and Cu/Pd-BTC_3 (representative samples with relatively<br />
low and high Pd-contents). Three Pd 3d doublets (3d5/2 and 3d3/2) are resolved in the<br />
deconvoluted spectra. The doublet located at 337.9 and 343.2 eV (Pd2) is characteristic<br />
for Pd 2+ species (Table 5.3). [288-289] In addition, the higher binding energies observed at<br />
338.9 and 344.2 eV for Pd1 reveal the presence of an electronically modified Pd 2+ species.<br />
Moreover, we could unambiguously rule out an assignment of both Pd 2+ species to PdO
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