The
development of a general synthesis approach for creating fine
alloyed nanoparticles (NPs) in the pores of metal–organic frameworks
(MOFs) shows great promise for advanced synergetic catalysis but has
not been realized so far. Herein, for the first time we proposed a
facile and general strategy to immobilize ultrafine alloyed NPs within
the pores of an MOF by the galvanic replacement of transition-metal
NPs (e.g., Cu, Co, and Ni) with noble-metal ions (e.g., Pd, Ru, and
Pt) under high-intensity ultrasound irradiation. Nine types of bimetallic
alloyed NPs of base and noble metals were successfully prepared and
immobilized in the pores of MIL-101 as a model host, which showed
highly dispersed and well-alloyed properties with average particle
sizes ranging from 1.1 to 2.2 nm and high loadings of up to 10.4 wt
%. Benefiting from the ultrafine particle size and high dispersity
of Cu–Pd NPs and especially the positive synergy between Cu
and Pd metals, the optimized Cu–Pd@MIL-101 exhibited an extremely
high activity for the homocoupling reaction of phenylacetylene under
unprecedented base- and additive-free conditions and room temperature,
affording at least 19 times higher yield (98%) of 1,4-diphenylbuta-1,3-diyne
than its monometallic counterparts. This general strategy for preparing
various MOF-immobilized alloyed NPs potentially paves the way for
the development of highly active metal catalysts for a variety of
reactions.