Electrochemical Reduction of Carbon Dioxide: Investigating Tunable Porosity and Surface Morphology in PFPE Gas Diffusion Layers for Enhanced Ethylene Selectivity

The electrochemical reduction of carbon dioxide (CO2) into higher-value materials has emerged as a promising avenue towards establishing a sustainable solar-fuel-based economy. Much work has been done in recent literature to improve selectivity towards C₂+ products, notably, copper has exhibited distinctive catalytic properties by yielding higher-order hydrocarbon products, predominantly methane, ethylene, and ethanol, with compelling efficiencies. Consequently, substantial research efforts have been dedicated to understanding the unique catalytic characteristics of copper and unraveling the underlying mechanism governing the formation of hydrocarbons. These mechanistic insights, coupled with the understanding of CO2 reduction mechanisms on other metals and molecular complexes, serve as pivotal guidelines for designing future catalyst materials capable of efficiently and selectively converting CO2 into valuable products. To overcome the inherent solubility limitations of gaseous CO2, our electrochemical cell operates with CO2 in the gas phase. Leveraging the enhanced transport properties and reduced diffusion length of gaseous CO2 to the electrode surface, we employ a gas diffusion layer (GDL) made of a hydrophobic porous material, specifically PFPE (perfluoropolyether). This PFPE-based GDL facilitates the delivery of gas phase CO2 to the electrocatalytic interface.<br/>Our research centers on the controllable and tunable porosity and surface morphology of the PFPE material within the gas diffusion layer. By varying the outer morphology of the catalyst surface, we aim to selectively tune the GDL to yield higher-order reduction products, particularly focusing on enhancing the production of ethylene. Through comprehensive studies and characterization, we investigate the influence of PFPE material properties, including porosity and surface morphology, on CO2 reduction and ethylene selectivity. By gaining insights into the correlation between the structural characteristics of the gas diffusion layer and the electrochemical performance, we aim to optimize the PFPE material design for efficient and selective CO2 reduction, specifically targeting ethylene as the desired product.<br/>This research sheds light on the crucial role of gas diffusion layers and their tailored characteristics in achieving desired electrochemical CO2 reduction outcomes. The findings contribute to the development of advanced catalyst materials and pave the way for scalable and sustainable strategies in utilizing CO2 as a valuable feedstock for the production of high-value carbon products.<br/><br/> <b>This work was performed under the auspices of the U.S. Department of Energy by Lawrence</b><br/><b>Livermore National Laboratory under Contract DE-AC52-07NA27344.</b>