In
recent years, based on the high catalytic activities of metal
nanoclusters (MNCs) and the unique porous structure of metal–organic
frameworks (MOFs), much work has focused on MOF-confined small MNCs
for catalysis applications. However, the commonly used “ship-in-boat”
approach is unfeasible for precisely controlling the size and composition
of the formed MNCs and meanwhile often causes structural distortion/degradation.
On the other hand, the “bottle-around-ship” method usually
has the disadvantages that MOFs show uncontrollable self-nucleation
outside the MNCs and the stabilizers on the surface of MNCs may greatly
reduce their catalytic activities. In this work, monodispersed Pt16(C4O4SH5)26 clusters
(Pt16(MSA)26) were first prepared and used as
a precursor for the synthesis of Pt(MSA)@ZIF-67 via the typical Co-carboxylate
type of linkage at the interface under ambient atmosphere. After encapsulating
the Pt clusters in ZIF-67, the protecting ligands were removed under
300 °C to get surface-clean Pt16 clusters confined
in ZIF-67 (Pt@ZIF-67). The obtained Pt@ZIF-67 exhibited high catalytic
activity for the hydrolysis of ammonia borane that was superior to
that of most of the reported noble-metal catalysts. Meanwhile, by
annealing the Pt(MSA)@ZIF-67 at 800 °C to form highly conductive
graphitic carbon-coated Pt NCs and Co nanoparticles (NPs) (Pt/Co@NC),
the obtained composite showed high catalytic activity for the oxygen
reduction reaction (ORR). The formed Pt/Co@NC showed 9.6 times higher
ORR mass activity (at 0.8 V) than Pt/C. This work provides a strategy
to fabricate highly dispersed and stable metal clusters confined in
the porous matrix for catalysis and shows that highly porous MOFs
have promising catalysis applications by combining them with other
active components.