Integrating Host Design and Tailored Electronic Effects of Yolk-Shell Zn-Mn Diatomic Sites for Efficient CO Electroreduction.

Modulating the surface and spatial structure of the host is associated with the reactivity of the active site, and also enhances the mass transfer effect of the CO electroreduction process (CO RR). Herein, we describe the development of two-step ligand etch-pyrolysis to access an asymmetric dual-atomic-site catalyst (DASC) composed of a yolk-shell carbon framework (Zn Mn -SNC) derived from S,N-coordinated Zn-Mn dimers anchored on a metal-organic framework (MOF). In Zn Mn -SNC, the electronic effects of the S/N-Zn-Mn-S/N configuration are tailored by strong interactions between Zn-Mn dual sites and co-coordination with S/N atoms, rendering structural stability and atomic distribution. In an H-cell, the Zn Mn -SNC DASC shows a low onset overpotential of 50 mV and high CO Faraday efficiency of 97 % with a low applied overpotential of 343 mV, thus outperforming counterparts, and in a flow cell, it also reaches a high current density of 500 mA cm at -0.85 V, benefitting from the high structure accessibility and active dual sites. DFT simulations showed that the S,N-coordinated Zn-Mn diatomic site with optimal adsorption strength of COOH* lowers the reaction energy barrier, thus boosting the intrinsic CO RR activity on DASC. The structure-property correlation found in this study suggests new ideas for the development of highly accessible atomic catalysts.