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Insights into the phenomenon of `bubble-free¿ electrocatalytic oxygen evolution from water

Journal Article


Abstract


  • Water electrolysis powered by renewable electricity will likely be critical to a future hydrogen economy. However, bubbles produced during water electrolysis add to capital and operational costs, due to blocking of the electrode surface and the necessary use of pumps and gas-liquid separators in electrolyser systems. Here ‘bubble-free’ electrocatalytic oxygen evolution from water was studied using a gas diffusion electrode that extracted oxygen as it was evolved, before bubbles were formed. The electrode comprised a gas-generating catalyst-binder layer, a poly(tetrafluoroethylene) (PTFE) interlayer, and a gas-extracting expanded PTFE (ePTFE) membrane (Gore-Tex®). Electrode properties between 20-60 °C, and with excess pressure on the alkaline electrolyte (≤80 kPa), were examined using detailed electrochemical measurements and video recordings. Electrochemical signal drift (dV/dt) was developed as a sensitive probe of bubble formation. ‘Breathability’, or the capacity for evolved oxygen to be directly extracted without forming bubbles, correlated with performance, and improved with temperature. A significant decline in oxygen evolution reaction (OER) activation energy with temperature was also observed. Bubble-free operation proceeded through the transportation of gas along a continuous network of hydrophobic, ‘aerophilic’ PTFE surfaces. The further development of bubble-free electrodes ought to permit revolutionary, low-cost electrolyser designs, adding impetus to the creation of a future hydrogen economy.

Publication Date


  • 2021

Citation


  • Tsekouras, G., Terrett, R., Yu, Z., Cheng, Z., Swiegers, G. F., Tsuzuki, T., . . . Pace, R. J. (2021). Insights into the phenomenon of `bubble-free¿ electrocatalytic oxygen evolution from water. Sustainable Energy and Fuels, 5(3), 808-819. doi:10.1039/d0se01633k

Scopus Eid


  • 2-s2.0-85100758057

Start Page


  • 808

End Page


  • 819

Volume


  • 5

Issue


  • 3

Abstract


  • Water electrolysis powered by renewable electricity will likely be critical to a future hydrogen economy. However, bubbles produced during water electrolysis add to capital and operational costs, due to blocking of the electrode surface and the necessary use of pumps and gas-liquid separators in electrolyser systems. Here ‘bubble-free’ electrocatalytic oxygen evolution from water was studied using a gas diffusion electrode that extracted oxygen as it was evolved, before bubbles were formed. The electrode comprised a gas-generating catalyst-binder layer, a poly(tetrafluoroethylene) (PTFE) interlayer, and a gas-extracting expanded PTFE (ePTFE) membrane (Gore-Tex®). Electrode properties between 20-60 °C, and with excess pressure on the alkaline electrolyte (≤80 kPa), were examined using detailed electrochemical measurements and video recordings. Electrochemical signal drift (dV/dt) was developed as a sensitive probe of bubble formation. ‘Breathability’, or the capacity for evolved oxygen to be directly extracted without forming bubbles, correlated with performance, and improved with temperature. A significant decline in oxygen evolution reaction (OER) activation energy with temperature was also observed. Bubble-free operation proceeded through the transportation of gas along a continuous network of hydrophobic, ‘aerophilic’ PTFE surfaces. The further development of bubble-free electrodes ought to permit revolutionary, low-cost electrolyser designs, adding impetus to the creation of a future hydrogen economy.

Publication Date


  • 2021

Citation


  • Tsekouras, G., Terrett, R., Yu, Z., Cheng, Z., Swiegers, G. F., Tsuzuki, T., . . . Pace, R. J. (2021). Insights into the phenomenon of `bubble-free¿ electrocatalytic oxygen evolution from water. Sustainable Energy and Fuels, 5(3), 808-819. doi:10.1039/d0se01633k

Scopus Eid


  • 2-s2.0-85100758057

Start Page


  • 808

End Page


  • 819

Volume


  • 5

Issue


  • 3