Photoelectrochemical electrodes
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorsRoger M. Williams, Alan Rembaum
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Abstract
The surface (20) of a moderate band gap semiconductor (12) such as p-type molybdenum sulfide is modified to contain an adherent film (24) of charge mediating ionene polymer containing an electroactive unit such as bipyridinium. Electron transport between the electrode (12) and the mediator film (24) is favorable and photocorrosion and recombination processes are suppressed. Incorporation of particles (26) of catalyst such as platinum within the film (24) provides a reduction in overvoltage. The polymer film is readily deposited on the electrode surface and can be rendered stable by ionic or addition cross-linking. Catalyst can be predispersed in the polymer film or a salt can be impregnated into the film and reduced therein.
Claims23
An electrode for an electrochemical cell comprising:
- a conductive substrate;
- and
- a film of stable, electrolyte-permeable, charge-mediating, conductive, polymer containing quaternized bipyridyl groups and cross-links between unsaturated groups on different polymer chains deposited on a surface of the substrate.
A method of forming a modified electrode comprising the step of depositing by in situ polymerization a film of electrolyte permeable, charge-mediating conductive polymer containing quaternized bipyridyl groups and cross-links between unsaturated groups on different polymer chains on the surface of a conductive substrate.
A modified photoelectrode comprising a solid semi-conductor having a band gap below 2.0 eV coated with a film of polyquaternary, bipyridyl polymer containing cross-links between unsaturated groups on different chains and a dispersion of fine, hydrogen producing catalyst.
A method of photolysing water comprising placing an electrode comprising a solid semiconductor having a band gap below 2.0 eV coated with a film of polyquaternary, bipyridyl polymer containing cross-links between unsaturated groups on different chains and a dispersion of fine, hydrogen producing catalyst, and a counterelectrode in aqueous electrolyte;
- illuminating the coated electrode with solar energy;
- photolysing water to produce hydrogen gas;
- and
- collecting said gas.
Dependencies are inferred from the claim text.