Improved Electrochemical Reduction of CO2 to Syngas with Highly Exfoliated Ti3C2Tx MXene-Gold Composite

Abstract

Transforming carbon dioxide (CO2) into valuable chemicals via electroreduction presents a sustainable and viable approach to mitigate the excess CO2 in the atmosphere. This report provides fresh insights into the design of a new titanium-based MXene composite as catalyst for the efficient conversion of CO2 in a safe aqueous medium. Despite its excellent electrocatalytic activity towards CO2 reduction and high selectivity for CO production, the high cost of Au and decline in catalytic activity on a larger scale hinders its large-scale CO2 conversion activities. In this research, we have successfully prepared Au/Ti3C2Tx composite and tested its catalytic activity in electrochemical CO2 reduction reaction (ECRR). The as-prepared composite features strong interactions between gold atoms and the Mxenes support, achieved through the formation of metal-oxygen/carbon bonds. The Au/Ti3C2Tx electrode demonstrated a significant current density of 17.3 mA cm-2 at a potential of -0.42 V vs. RHE, in CO2 saturated atmosphere (Faradaic Efficiency: CO = 48.3%, H2 = 25.6%). Nyquist plots further indicated a reduction in the charge-transfer resistance of the Au/Ti3C2Tx layer, signifying rapid charge transfer between the Au and Ti3C2Tx. Further, it is known that liquid crossover through the Gas Diffusion Electrode (GDE) significantly improves CO2 diffusion to catalyst active sites, thereby enhancing CO2 conversion efficiency. The goal of this work is to design an interface between metal and MXene so that CO2 can be electroreduced into fuels and other useful chemical compounds with great selectivity.