Interfacial Engineering of ZIF-67@Ti3C2Tx MXene Hybrids for Selective Electrochemical CO2 Reduction to C1 Products

Abstract

Electrochemical CO2 reduction (CO2RR) enables conversion of CO2 into fuel-relevant products using renewable electricity, but aqueous systems are often limited by hydrogen evolution reaction (HER) and mass-transport constraints. Here, a ZIF-67@Ti3C2Tx MXene hybrid electrocatalyst is prepared via in situ growth of cobalt-based ZIF-67 nanoparticles on conductive Ti3C2Tx sheets synthesized using a mild LiF/HCl etching route. The catalytic performance is systematically evaluated in both H-cell and gas-fed flow-cell configurations. Among the investigated compositions (15, 30, and 45 wt.%), ZIF(30%)@Ti3C2Tx provides the most favorable balance between conductivity and accessible catalytic site density. Under gas-fed flow-cell operation, ZIF(30%)@Ti3C2Tx reaches its highest CO2RR selectivity at −0.8 V vs RHE, delivering ∼84% total Faradaic efficiency toward carbon-containing products (dominated by methane and methanol) while maintaining stable performance over 10 h of continuous electrolysis. In comparison, ZIF-67 requires a more negative potential to reach its best performance and exhibits lower carbon-product selectivity due to stronger competition from HER. These results highlight how MOF–MXene interfacial engineering, together with a flow-cell configuration, can improve charge transport and active-site utilization to enhance aqueous CO2 electroreduction selectivity and stability.