The precursor Pd(PPh3)4 for the preparation of Pd@MOF could not catalyze the reaction as well (Table , entry 5), even though there will be palladium black precipitation leading to the deterioration of Pd(PPh3)4 after the reaction. Additionally, the NH2-MIL-125 (Ti) MOF could not promote the reaction (Table The abovementioned experimental results clearly suggest that Pd@MOF can catalyze the reductive reaction of aldehyde efficiently because of the synergetic effect of the MOF skeleton and highly dispersed Pd particles. In summary, Pd in situ encapsulation during the self-assembly of MOF for avoiding the aggregation and oxidation of palladium, thereby improving the catalytic activity of the loaded metal.