Role of Binder in Cu₂O Gas Diffusion Electrodes for CO₂ Reduction to C₂₊ Products
2022
Kim, Young Eun | Lee, Wonhee | Ko, You Na | Park, Jeong Eun | Tan, Daniel | Hong, Jumi | Jeon, Ye Eun | Oh, Jihun | Park, Ki Tae
The electrochemical CO₂ reduction reaction (CO₂RR) to form C₂₊ products was investigated to obtain high selectivity in liquid CO₂-fed systems having the limitation of low current density. Over the past decade, flow cells with gas diffusion electrodes (GDEs) have emerged to achieve high current densities close to the industrial-relevance scale by overcoming gas diffusion limitations. However, key parameters of GDE design, including binders, were not sufficiently identified to enhance selectivity and current density for C₂₊ products. Nafion, FAA-3, and polypyrrole were used to explore the effects of binder type and content on GDE properties such as porosity (gas permeability), ion conductivity, and electron conductivity for the modulation of the CO₂RR on the Cu₂O catalyst. The Cu₂O GDEs with high binder content showed poor selectivity for C₂₊ products because of their low exposure to the catalyst surface and decreased gas permeability. The anion exchange ionomer, FAA-3, showed high selectivity for C₂₊ products and electrode stability resulting from the C–C coupling increase and suppression of the hydrogen evolution reaction, which was induced by OH– conductivity. In contrast, the cation exchange ionomer, Nafion, exhibited low electrode stability due to the loss of gas products through the catholyte and due to its excessive wettability.
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