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

Xuan Qiu,Zhijie Chen,Xinwei Zou,Yingwei Li,Ruiqi Fang,Liyu Chen,Jianmin Chen,Kui Shen

doi:10.1039/c8sc03549k

Abstract

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.

Highlights

Owing to sustainable development in energy and environment areas, metal sub-nanoclusters (MSNCs) have attracted extensive attention due to their fascinating catalytic properties stemming from their high atom efficiencies.[1,2] In particular, isolated single atoms (SAs) as an exceptional case feature atomically dispersed metal atoms and maximum atom utilization, which have resulted in superior catalytic performance in a number of reactions.[3]
The residual character of pyridine-type (C–N) fragments derived from the organic ligands of the MOP were supposed to act as in situ formed stabilizers to prevent the metal from aggregating, achieving highly dispersed C–N-decorated MSNCs/SAs, which were further stabilized by the con nement effect offered by the metal–organic framework (MOF) cages
We have developed a facile strategy to fabricate highly dispersed C–N-decorated MSNCs/SAs that were encapsulated in the pores of a MOF

Summary

Introduction

Owing to sustainable development in energy and environment areas, metal sub-nanoclusters (MSNCs) have attracted extensive attention due to their fascinating catalytic properties stemming from their high atom efficiencies.[1,2] In particular, isolated single atoms (SAs) as an exceptional case feature atomically dispersed metal atoms and maximum atom utilization, which have resulted in superior catalytic performance in a number of reactions.[3]. The residual C–N fragments derived from the organic ligands of the MOP were supposed to act as in situ formed stabilizers to prevent the metal from aggregating, achieving highly dispersed C–N-decorated MSNCs/SAs, which were further stabilized by the con nement effect offered by the MOF cages. The PXRD patterns of all PCN3M (Fig. S5†) hybrids were similar to that of MIL-101 and no characteristic peak of the Pd phase was observed, suggesting the well-preserved structure of the parent MIL-101 and the high dispersion of Pd in PCN3M.12,14 The transformation of M6L4 in M6L43MIL-101 a er pyrolysis was further con rmed by FT-IR.

Results

Conclusion