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Chapter 5 137
The phase purity and good crystallinity of Cu/Pd-BTC_4 have been proved by the
comparison of the PXRD patterns (Figures 5.13) before and after activation with those
simulated from the single crystal XRD data of the reported [Cu3(BTC)2]n (Cu-BTC_sim). [35]
Notably, the PXRD patterns of the Cu/Pd-BTC_4 sample display higher relative intensity
of the (222) reflection, which is different with the intensity of that in the parent Cu-BTC.
This suggests certain electronic modification on the metal nodes in the framework (e.g.
Pd 2+ substitution of Cu 2+ -sites). However, the presence of Pd NPs could not be precisely
determined by PXRD. No apparent reflections at 40.02 and 46.59 °originating from (111)
and (200) planes of the face-centered cubic structure of Pd are found in the PXRD patterns
of the Cu/Pd-BTC_4. [286] This can be due to the rather small particle size of NPs.
Cu/Pd-BTC_4
Cu-BTC
H 3
BTC
4000 3500 3000 2500 2000 1500 1000 500
wavenumber, cm -1
Figure 5.14. IR spectra of the Cu/Pd-BTC_4 solid in comparison with the parent Cu-BTC and the
starting linker H 3 BTC.
In addition, no vibrations stemming from the non-reacted H3BTC linker or employed
metal-precursors (i.e. nitrate groups) could be observed in the FT-IR spectra of the