Penta-Coordinated Y Sites Modulated Single Bi Sites for Promoted Selectivity of Electrochemical CO2 Reduction

Atomically dispersed catalysts with two active sites have attracted attention in recent years. The two different sites may act synergistically in catalytic reactions or one site as active site and another regulates it. In this work, rare earth (RE)-based single-atom combo catalyst BiY/CN (with Y penta-coordinated) is synthesized and characterized carefully for electrochemical reduction of CO2 to formic acid for the first time. The state of active Bi and Y species in the prepared catalyst is proved by the extended X-ray absorption fine structure spectra and aberration-corrected high-angle annular dark field scanning transmission electron microscopy. The comprehensive experimental results and density functional theory calculations show Y sites covered by hydroxyls not only avoid being poisoned by *HCO2 at working conditions, but also serve as a spectator to affect the charge state of Bi sites, promoting performance by facilitating the transformation of *HCO2 intermediate to HCOOH. This work provides a new perspective on RE elements in electrocatalytic carbon dioxide reactions in future studies.

Automated summary

This work presents the synthesis and characterization of a rare earth-based single-atom combo catalyst BiY/CN for electrochemical reduction of CO2 to formic acid. The experimental results show that the Y sites in the catalyst, covered by hydroxyls, not only avoid poisoning but also affect the charge state of Bi sites, promoting catalytic performance.