Confined Synthesis of Dual-Atoms Within Pores of Covalent Organic Frameworks for Oxygen Reduction Reaction.

Dual-atom catalysts exhibit higher reactivity and selectivity than the single-atom catalysts. The pyrolysis of bimetal salt precursors is the most typical method for synthesizing dual-atomic catalysts; however, the finiteness of bimetal salts limits the variety of dual-atomic catalysts. In this study, a confined synthesis strategy for synthesizing dual-atomic catalysts is developed. Owing to the in situ synthesis of zeolitic imidazolate frameworks in the pores of covalent organic frameworks (COFs), the migration and aggregation of metal atoms are suppressed adequately during the pyrolysis process. The resultant catalyst contains abundant ZnCo dual atomic sites with 2.8 wt.% Zn and 0.5 wt.% Co. The catalyst exhibits high reactivity toward oxygen reduction reaction with a half-wave potential of 0.86 V, which is superior to that of the commercial Pt/C catalyst. Theoretical calculations reveal that the Zn atoms in the ZnCo dual atomic sites promote the formation of intermediate OOH*, and thus contribute to high catalytic performance. This study provides new insights into the design of dual-atom catalysts using COFs. The strategy of confined synthesis based on the covalent organic frameworks has been demonstrated to construct dual atomic catalysts. The synthesized catalyst has ZnCo atomic centers, which enables it to catalyze the oxygen reduction reaction with high activity and selectivity.image