Improved electrochemical reduction of CO2 to syngas with a highly exfoliated Ti3C2Tx MXene–gold composite

Abstract

Transforming carbon dioxide (CO₂) into valuable chemicals via electroreduction presents a sustainable and viable approach to mitigating excess CO₂ in the atmosphere. This report provides fresh insights into the design of a new titanium-based MXene composite as a 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 the decline in catalytic activity on a larger scale hinder its large-scale CO₂ conversion applications. In this research, we have successfully prepared an Au/Ti₃C₂T_x composite and tested its catalytic activity in the electrochemical CO₂ reduction reaction (ECRR). The as-prepared composite features strong interactions between gold atoms and the MXene support, achieved through the formation of metal–oxygen/carbon bonds. The Au/Ti₃C₂T_x electrode demonstrated a significant current density of 17.3 mA cm⁻² at a potential of −0.42 V vs. RHE, in a CO₂ saturated atmosphere (faradaic efficiency: CO = 48.3% and H₂ = 25.6%). Nyquist plots further indicated a reduction in the charge-transfer resistance of the Au/Ti₃C₂T_x layer, signifying rapid charge transfer between the Au and Ti₃C₂T_x. Furthermore, 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 to fuels and other useful chemical compounds with great selectivity.