Breathable electrode structure and method for use in water splitting
The present invention relates to a water splitting cell having at least one electrode comprising a porous membrane, wherein gas produced at the electrode diffuses out of the cell via the porous membrane, separating the gas from the reaction at the electrode without bubble formation.
1. A method of splitting water into hydrogen and oxygen in a water-splitting electrolysis cell, the method comprising:
combining a first electrode having a conducting layer on a surface of a porous gas-permeable hydrophobic polymer membrane and a catalyst over the conducting layer with a counter-electrode in an electrochemical cell containing an aqueous electrolyte;
applying a current to the electrochemical cell to produce hydrogen gas and oxygen gas from the aqueous electrolyte; and
separately collecting the produced hydrogen gas directly from the first electrode and oxygen gas from the counter-electrode.
2. The method of claim 1 , wherein collecting the hydrogen gas comprises collecting the hydrogen gas directly from the porous gas-permeable hydrophobic polymer membrane.
3. The method of claim 1 , wherein the conducting layer is gold.
4. The method of claim 1 , further comprising performing a surface treatment on the porous gas-permeable hydrophobic polymer membrane prior to applying the conducting layer to the surface.
5. The method of claim 4 , wherein the surface treatment comprises a plasma treatment.
6. The method of claim 4 , wherein the surface treatment comprises a polyacid treatment.
7. The method of claim 6 , wherein the surface treatment comprises treating the membrane with maleic anhydride.
8. The method of claim 1 , wherein the catalyst layer comprises platinum.
9. The method of claim 1 , wherein the catalyst is a metal or a metal compound.
10. The method of claim 9 , wherein the catalyst comprises one or more of the following: Pd, Ru, Ir, Mn, Fe, Ni, Co, NiO x , Mn complexes, Fe complexes, MoS x , CdS, CdSe, and GaAs.
11. The method of claim 1 , wherein the polymer membrane is a polytetrafluoroethylene (PTFE) membrane.
12. The method of claim 1 , wherein the polymer membrane comprises one or more of polyethylene (PE), polypropylene (PP), poly n-butyl methacrylate (PnBMA), polytrifluoroethylene, nylon, polybutadiene, and polychlorotrifluoroethylene (PCTFE).
13. The method of claim 1 , wherein the polymer membrane comprises one or more of polydimethylsiloxane (PDMS), poly t-butyl methacrylate (PtBMA), fluorinated ethylene propylene (FEP), hexatriacontane, paraffin, poly(hexafluoropropylene), and polyisobutylene (PIB, butyl rubber).
14. The method of claim 1 , wherein the porous membrane has a pore size of less than 0.5 μm.
15. The method of claim 14 , wherein the porous membrane has a pore size of less than 0.1 μm.
16. The method of claim 15 , wherein the porous membrane has a pore size of less than 0.05 μm.
17. The method of claim 1 , wherein the porous membrane has a contact angle greater than 90°.
18. The method of claim 1 , wherein the porous membrane has a contact angle from 100° to 115°.