MOFs-Templated Co@Pd Core–Shell NPs Embedded in N-Doped Carbon Matrix with Superior Hydrogenation Activities

Abstract

Although MOFs supporting noble metal nanoparticles (NPs) have been widely used in heterogeneous catalysis, they are still limited in catalytic efficiency on a per-noble-metal-atom basis. Here we developed a MOFs-templated strategy to non-noble metal @noble metal core–shell nanocatalysts, which could far surpass the traditional MOFs supporting noble NPs in catalytic properties, by using MOFs-derived metal NPs as sacrificial templates to reduce noble metal ions via galvanic replacement reaction. As a model system, Co@Pd core–shell NPs embedded in the N-doped carbon matrix (Co@Pd/NC) were synthesized with an average size of ca. 9.4 nm and a ultrathin Pd shell by using ZIF-67 and Pd(NO 3 ) 2 as the precursor and Pd source, respectively. The highly exposed Pd atom on Co nanoparticles made it an attractive catalyst with high efficiency. When being used in the hydrogenation of nitrobenzene, the Co@Pd/NC exhibited an unprecedented high activity over Pd-based catalysts, yielding 98% conversion after 45 min reaction, which was far more active than the pristine ZIF-67 and MIL-101 supporting Pd NPs (with 40% and 3% conversion after 90 min reaction, respectively) under identical conditions, suggesting its overwhelmingly better performance than MOFs supporting noble NPs. We anticipated that this strategy would form the basis for developing a new class of MOF-templated core–shell nanocatalyst with potential applications in numerous catalytic reactions.