Integration of Cu-based MOF electrocatalysts into gas diffusion layers: Insights into CO2 reduction performance

Abstract

Carbon dioxide (CO₂) is a major greenhouse gas, and its high emission from industrial activities poses significant environmental challenges. The electrochemical reduction of CO₂ (CO₂RR) offers a promising strategy to convert CO₂ into valuable products such as ethylene (C₂H₄), methane (CH₄), carbon monoxide (CO), methanol (CH₃OH), and ethanol (C₂H₆O). In this study, we report the integration of Cu-based metal-organic framework (MOF) electrocatalysts into gas diffusion layers (GDLs) to enhance CO₂RR performance. Electrocatalysts, specifically Cu/ZnO-UiO66 and Cu/ZnO-MDC, were deposited onto GDLs using an air-spraying technique, ensuring a homogeneous distribution of active metals across the substrate. Comprehensive characterisation of the modified GDLs was performed using field-emission scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (FESEM-EDX), X-ray diffraction (XRD), and tensiometer to assess surface morphology, textural properties, and phase composition, respectively. The deposition process resulted in a notable increase in hydrophilicity compared to pristine GDLs, as indicated by reduced contact angles. CO₂RR experiments conducted in a liquid flow system demonstrated that the Cu/ZnO-UiO66-based GDL achieved FEs of 40 % for CO production, 6 % for CH₄, and 3 % for C₂H₄, at a cathodic potential of −1.0 V vs RHE. In contrast, the Cu/ZnO-MDC-based GDL delivered FEs of 17 % for CO and 10 % C₂H₄, as well as 2 % for CH₄, under similar conditions. These findings underscore the potential of Cu-based MOF electrocatalysts in enhancing CO₂ reduction processes. However, further optimization of the catalyst properties and deposition techniques is necessary to improve performance and selectivity, paving the way for more efficient CO₂ conversion technology.