(544e) Highly Selective Electrochemical Reduction of CO2 to CO Via a Novel Catalyst with Mn-N3 Site

Electrochemical CO₂ reduction reaction (CO₂RR) is one of the most promising ways to deal with the excess CO₂ and resolve the energy crisis ^[1]. However, due to the stability of CO₂ molecule and reaction involves multiple electrons and protons, poor selectivity and low current density are the main challenges of this filed ^[2]. So, efficient catalysts are in great need.

As the third abundance of transition metals in Earth’s crust, manganese (Mn) has shown great potentials on many electrocatalytic fields. Nevertheless, the performance of Mn based catalysts is largely limited for CO₂RR. Herein, we firstly prepared Mn single-atom catalyst (SAC) with Mn-N₃ site supported by g-C₃N₄. The prepared catalyst exhibited a maximum CO FE of 98.8% with 14.0 mA cm^-2 CO current density (j_CO) at overpotential of 0.44 V in KHCO₃ electrolyte, outperforming all reported Mn SACs and being one of the best reported electrocatalysts for CO₂ conversion CO. Moreover, a higher j_CO value of 29.7 mA cm^-2 was obtained at overpotential of 0.62 V, when ionic liquid was used as electrolyte. In-situ experiment and DFT results confirmed that Mn-N₃ site is the active site, on which the free energy barrier of key intermediate formation is greatly reduced. It can be anticipated that Mn SACs may also exhibit excellent performance in other electrochemical reactions through changing supporting materials to form exclusive active site.

References

[1] Feng JQ, Gao HS, Feng JP, Liu L, Zeng SJ, Dong HF, Bai YG, Liu LC, Zhang XP. Morphology modulation‐engineered flowerlike In₂S₃ via ionothermal method for efficient CO₂ Electroreduction. ChemCat Chem, 2020, 12: 926-931.

[2] Feng JP, Zeng SJ, Liu HZ, Feng JQ, Gao HS, Bai L, Dong HF, Zhang SJ, Zhang XP. Insights into carbon dioxide electroreduction in ionic liquids: Carbon dioxide activation and selectivity tailored by ionic microhabitat. ChemSusChem, 2018, 11: 3191-3197.