Computational studies of ionic liquids as co-catalyst for CO₂ electrochemical reduction to produce syngas using COSMO-RS

¹ Chemical Engineering Department, Universiti Teknologi PETRONAS, 32610 Seri Iskandar, Perak, Malaysia
² Centre of Research in Ionic Liquids, Universiti Teknologi PETRONAS, 32610 Seri Iskandar, Perak, Malaysia

^* Corresponding author: zaireen.yahya@utp.edu.my

Abstract

Transforming carbon dioxide (CO₂) into value-added products through electrochemical reduction reaction (CO₂ERR) is a promising technique due to its potential advantages using renewable energy. The main challenge is to find a stable catalytic system that could minimize the reaction overpotential with high faradaic efficiency and high current density. Ionic liquids (ILs) as electrolyte in CO₂ERR have attracted attention due to the advantages of their unique properties in enhancing catalytic efficiency. For better performance, a systematic understanding of the role of ILs as electrocatalyst is needed. Therefore, this paper aims to correlate the performance of ILs as co-catalyst in (CO₂ERR) with the lowest unoccupied molecular orbital (LUMO) energy level and the interaction energy as predicted by quantum chemical calculation using Conductor like Screening Model for Real Solvents (COSMO-RS) and Turbomole. The results show strong linearity (R²=0.98) between hydrogen bond energy (HB) and LUMO values. It is demonstrated that as HB increases, the LUMO value decreases, and the catalytic activity for CO₂ERR also increases. This result allows further understanding on the correlation between the molecular structure and the catalytic activity for CO₂ERR. It can serve as a priori prediction to aid in the design of new effective catalysts.