(558at) Highly Selective Electrochemical Reduction of CO2 to Formate Via Ultrathin Nanosheet in2S3 in Ionic Liquid

Authors: 
Feng, J., University of Chinese Academy of Sciences
Gao, H., Institute of Process Engineering, Chinese Academy of Sciences
Zhang, S., Beijing Key Laboratory of Ionic Liquids Clean Process,CAS Key Labroratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences
Zhang, X., Beijing Key Laboratory of Ionic Liquids Clean Process,CAS Key Labroratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences
Efficient conversion of greenhouse gas CO2 into value-added liquid fuels is one of the most promising ways to deal with the excess CO2 and resolve the energy crisis. Furthermore, it can use renewable electricity to drive the process and the reaction could occur at ambient conditions [1]. However, due to the stability of the CO2 molecule and reaction involves multiple electrons and protons, poor selectivity, low product formation rate and high overpotential are the main challenges of this filed [2]. So, efficient catalysts are in great need to break its thermodynamic stability and overcome the kinetically sluggish of reaction.

Indium (In) is a good catalyst for electrochemical reduction of CO2 to formate (FE > 60%), However, the current density of indium catalysts is usually low, which results in a poor formate formation rate (< 100 μmol h-1 cm-2). Recently, it was reported that two-dimensional metal chalcogenides exhibit good activity of electrochemical reduction of CO2 because of their unique physical and chemical properties. Herein, we carried out the first work on electrochemical reduction of CO2 to formate using ultrathin nanosheet In2S3 prepared by ionothermal synthesis in ionic liquid (IL) electrolyte. The new catalyst exhibited a large formate formation rate and high formate Faradaic Efficiency (FE). The simulation results show that the preferential crystallographic orientation of nanosheet In2S3, (311) facet, is more favorable to stabilize the reaction intermediate (OCHO*) and desorb HCOOH(ads) to form a stable liquid product HCOOH, which is a main reason for excellent performance. This work offers a simple strategy to promote electrochemical reduction of CO2 performance through changing structure and preferential crystallographic orientation of metal sulfide.

References

[1] Zeng SJ, Zhang XP, Bai L, Zhang XC, Wang H, Wang JJ, Bao D, Li MD, Liu XY and Zhang SJ. Ionic-Liquid-Based CO2 Capture Systems: Structure, Interaction and Process. Chemical Reviews, 2017, 117: 9625-9673.

[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.