Effect of Dispersing Solvents for an Ionomer on the Performance of Copper Catalyst Layers for CO₂ Electrolysis to Multicarbon Products

Effect of Dispersing Solvents for an Ionomer on the Performance of Copper Catalyst Layers for CO₂ Electrolysis to Multicarbon Products

Idros, Mohamed Nazmi (University of Queensland)
Wu, Yuming (University of Queensland)
Duignan, Timothy (University of Queensland)
Li, Mengran (TU Delft ChemE/Materials for Energy Conversion and Storage)
Cartmill, Hayden (University of Queensland)
Maglaya, Irving (University of Queensland)
Burdyny, T.E. (TU Delft ChemE/Materials for Energy Conversion and Storage)
Wang, Geoff (University of Queensland)
Rufford, Thomas E. (University of Queensland)

2023

To explore the effects of solvent-ionomer interactions in catalyst inks on the structure and performance of Cu catalyst layers (CLs) for CO₂ electrolysis, we used a “like for like” rationale to select acetone and methanol as dispersion solvents with a distinct affinity for the ionomer backbone or sulfonated ionic heads, respectively, of the perfluorinated sulfonic acid (PFSA) ionomer Aquivion. First, we characterized the morphology and wettability of Aquivion films drop-cast from acetone- and methanol-based inks on flat Cu foils and glassy carbons. On a flat surface, the ionomer films cast from the Aquivion and acetone mixture were more continuous and hydrophobic than films cast from methanol-based inks. Our study’s second stage compared the performance of Cu nanoparticle CLs prepared with acetone and methanol on gas diffusion electrodes (GDEs) in a flow cell electrolyzer. The effects of the ionomer-solvent interaction led to a more uniform and flooding-tolerant GDE when acetone was the dispersion solvent (acetone-CL) than when we used methanol (methanol-CL). As a result, acetone-CL yielded a higher selectivity for CO₂ electrolysis to C₂₊ products at high current density, up to 25% greater than methanol-CL at 500 mA cm^-2. Ethylene was the primary product for both CLs, with a Faradaic efficiency for ethylene of 47.4 ± 4.0% on the acetone-CL and that of 37.6 ± 5.5% on the methanol-CL at a current density of 300 mA cm^-2. We attribute the enhanced C₂₊ selectivity of the acetone-CL to this electrode’s better resistance to electrolyte flooding, with zero seepage observed at tested current densities. Our findings reveal the critical role of solvent-ionomer interaction in determining the film structure and hydrophobicity, providing new insights into the CL design for enhanced multicarbon production in high current densities in CO₂ electrolysis processes.

Aquivion conformation
catalyst ink formulation
electrochemical CO reduction
perfluorinated sulfonic acid (PFSA) ionomer
solubility parameter

http://resolver.tudelft.nl/uuid:44d2ba33-5e5b-473b-a131-6ecb16db9b24

https://doi.org/10.1021/acsami.3c11096

2024-05-06

1944-8244

ACS applied materials & interfaces, 15, 52461-52472

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Institutional Repository

journal article

© 2023 Mohamed Nazmi Idros, Yuming Wu, Timothy Duignan, Mengran Li, Hayden Cartmill, Irving Maglaya, T.E. Burdyny, Geoff Wang, Thomas E. Rufford