Encapsulation of C–N-decorated metal sub-nanoclusters/single atoms into a metal–organic framework for highly efficient catalysis

Fabrication and modification of few-atom metal clusters and even single atoms in the pores of porous materials for catalysis are highly desired from an atom-efficiency aspect but remain a great challenge. Herein, we propose a facile and efficient strategy for the encapsulation of C–N-decorated Pd sub-nanoclusters (MSNCs)/single atoms (SAs) into MOFs by the confined thermolysis of Pd-based metal–organic polyhedra (MOPs) in MOF pores. The obtained hybrids contained both Pd MSNCs (∼0.8 nm) and Pd SAs, which were stabilized by the in situ formed C–N fragments and the confinement effect of MOF pores. Benefiting from the highly exposed Pd atoms and synergistic effect between Pd and C–N fragments, these catalysts exhibited extremely high catalytic activity and stability in various important chemical processes, making them comparable to the most active Pd-based catalysts reported in the literature even under milder reaction conditions. Considering the high tunability of MOPs, this proposed strategy might provide a new toolbox for enriching the family of decorated MSNC/SA catalysts.