The low-angle powder XRD pattern of the prepared Pd@MOF (Figure , black line) matches well with that of the pristine NH2-MIL-125 reported by Li et al. After the incorporation of Pd particles, the structure of NH2-MIL-125(Ti) is well preserved for the 2.8 wt% Pd@MOF catalyst (Figure , red line). Additionally, no significant diffraction peak ascribed to Pd species is observed for the Pd@MOF and Pd-MOF catalyst from the wide-angle XRD pattern (Figure ). The Pd@MOF was characterized using X-ray Photoelectron Spectroscopy (XPS) technique, and the Pd3d results are displayed in Figure and eV, 337.6 eV, and 342.7 eV (Figure ), which reveals Pd 0 and Pd II of Pd species, which is due to the partial oxidation of Pd nanoparticles. Interestingly, the XPS spectra of immersed-Pd/MOF (Figure ) also reveals mixed oxidation states (Pd 0 and Pd II ) for Pd species. XPS results indicated that encapsulated Pd particles could inhibit Pd oxidation. As they are clearly shown in Figures and, the TEM images demonstrate that the Pd species are too small and dispersed within the NH2-MIL-125 (Ti). Compared with NH2-MIL-125 (Ti), the appearance of Pd@MOF is not changed. EDS analyses also confirm that the Pd species are evenly dispersed within MOF as shown in Figure .