CO2 Conversion by Electro-Catalysis Using Liquid Metal Systems

Abstract

Electrochemical CO2 reduction is one of the promising pathways for converting CO2 into valuable products but is often hindered by inefficiencies at the electrode interface. This study explores an innovative approach using room-temperature liquid metal electrocatalysts, focusing on gas purging strategies that introduce CO2 directly into the liquid metal (LM) rather than through the conventional electrolyte | electrode interface. Traditional methods of CO2 diffusion into the electrode's active sites create negative concentration gradients, which result in significant mass transport limitations as CO2 is consumed during the reduction process. These limitations severely impede the efficiency of electrochemical CO2 reduction systems. This research aims to demonstrate the benefits of purging CO2 directly through LM, utilizing a custom-designed electrochemical cell. This method aims to establish a positive concentration gradient at the interface, hypothesizing that bursting CO2 bubbles at the liquid metal interface will significantly enhance the availability of CO2, thus overcoming traditional mass transport limitations. Using three distinct purging strategies, this study examines how different methods of introducing CO2 into the liquid metal affect the overall reaction efficiency. The electrochemical cell's unique geometry is designed to facilitate the testing of each strategy for CO2 reduction. Electrochemical findings indicate a marked increase in current density at low potential compared to conventional purging protocol, leading to enhanced reduction rates without encountering the theoretical limitations of mass transport. Notably, the electrochemical CO2 reduction reaction facilitated the production of solid carbonous products at ambient conditions, namely carbon black (CB) and a series of gaseous products. By implementing this innovative purging technique, the study demonstrates a feasible approach to improving the electrochemical reduction of CO2 in LM systems. This exploration of purging strategies holds significant potential for enhancing the efficiency of CO2 conversion and demonstrating the reduction of economically viable products under ambient conditions.

Date of Award	8 May 2024
Original language	American English
Supervisor	Ludo Dumee (Supervisor)