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Mass-transport limits in a microfluidic GDE electrolyser
Communications Chemistry · 2024Gas diffusion electrodes deliver CO2 to the catalyst in the gas phase, but performance is still set by how fast reactants and products move through the porous layers and electrolyte.
Key findings
- Validated 2D model of the cathode side of a microfluidic CO2-to-CO flow cell with a gas diffusion electrode.
- With a fully flooded catalyst layer the CO partial current density peaks at 75 mA cm−2 at −1.3 V vs RHE, then falls as CO2 near the catalyst runs out.
- A large part of the catalyst layer stays underutilised; graded porosity and anisotropic layers are proposed to improve mass transport.
- Higher CO2 gas flow raises the CO current but lowers CO2 conversion efficiency: a clear trade-off.
What I did
- Two-dimensional model of a gas-diffusion cathode in a microfluidic flow cell, resolving coupled charge, species and momentum transport.
- Validated against experimental data.
- Quantified which transport processes limit performance and where.
- Interactive viewer and movie below: the model across the full potential sweep.
V. G. Agarwal, S. Haussener, Communications Chemistry 7, 47 (2024) — open access.
Funded by the EPFLglobaLeaders programme, which received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 945363, and by the Swiss National Science Foundation (project 200021_197268).
Ideally wetted vs. fully flooded
Dissolved CO2 (electrolyte channel, catalyst layer) and gaseous CO2 (GDL, gas channel) during the potential sweep, with the CO and H2 partial currents of the same models.
2D model of the microfluidic flow cell; frames computed every 0.05 V and interpolated in between. Panels have separate x scales; dotted lines mark the electrode ends.