Optimizing CO2RR selectivity on single atom catalysts using graphical construction and identification of energy descriptor.

The electrocatalytic reduction of CO 2 (CO 2 RR) into value-added hydrocarbons is limited due to high limiting potential (U L) and competing hydrogen evolution reaction (HER). To find the best catalyst for CO 2 reduction the concept of hydrogen poisoning was not considered in the catalyst screening process. Herein, we present a simple screening method and graphical construction using multiparameter optimization for the design of highly active and selective single-atom catalysts (SAC) using density functional theory calculations. A series of SAC namely, MN4, MBN3 and H@MBN3 (M: metal) are investigated for CO 2 RR. Our results revealed that MN4 and MBN3 SAC are not favorable for CO 2 RR due to high U L > −0.85 V and hydrogen poisoning (ΔG H* < 0), respectively. H@MBN3 SAC (stable compounds forming H–B bonds) are identified as efficient catalysts with a low value of U L and significantly hinder the competitive HER. Among these, H@CoBN3 and H@FeBN3 SAC show excellent CO 2 RR activity with limiting potential −0.30 and −0.44 V respectively for CH 4 production and no chance of HER. Scaling relations reveal the importance of *COOH/*CHO binding energy (E b) as an energy descriptor to evaluate the catalytic performance. This work provides a new theoretical perspective to design a highly selective catalyst for CO 2 RR. [Display omitted] • Simple graphical construction is provided to screen the catalyst for selective CO 2 RR. • The hydrogen poisoning issue is addressed, which blocks the active site. • Hydrogen assisted catalysts (H@MBN3) are designed for highly efficient CO 2 RR. • The binding energy of *COOH is defined as an energy descriptor for SAC catalyst. [ABSTRACT FROM AUTHOR]