Electrocatalyst ink
The present invention provides a method of preparing an electrocatalyst ink, the method comprising a step of contacting a dispersion with a separation material.
1. A method of preparing an electrocatalyst ink, the method comprising the steps of:
i) preparing a dispersion comprising an electrocatalyst material, an ion-conducting material and a diluent; then
ii) contacting the dispersion with a separation material comprising picolinic acid ester or picolinic acid amide functional groups immobilised on a solid support.
2. The method according to claim 1 , wherein the ion-conducting material is a proton conducting ionomer.
3. The method according to claim 1 , wherein the electrocatalyst material comprises an electrocatalyst which is a platinum group metal or an alloy of a platinum group metal with a base metal.
4. The method according to claim 1 , wherein the electrocatalyst is supported on a support material.
5. The method according to claim 1 , wherein step i) includes a step of breaking up agglomerates in the dispersion.
6. The method according to claim 5 , wherein the step of breaking up agglomerates in the dispersion is carried out by ball milling.
7. The method according to claim 1 , wherein step ii) comprises dispersing the separation material in the dispersion prepared in step ii), and the method further comprises a step iii) of filtering the dispersion to remove the separation material.
8. The method according to claim 7 , wherein the dispersion is agitated in step ii).
9. The method according to claim 1 , wherein step ii) comprises passing the dispersion through a column packed with the separation material.
10. The method according to claim 1 , wherein step ii) comprises placing a vessel containing the separation material in the dispersion, wherein the vessel is permeable to the dispersion, but is not permeable to the separation material.
11. A method of applying an electrocatalyst layer to a substrate, the method comprising the steps of:
i) preparing an electrocatalyst ink by the method of claim 1 ; then
ii) applying the electrocatalyst ink onto the substrate and drying the ink to form an electrocatalyst layer.
12. A method of preparing a gas diffusion electrode, the method comprising applying an electrocatalyst layer to a substrate according to the method of claim 11 , wherein the substrate is a face of a gas diffusion layer.
13. A method of preparing a membrane electrode assembly, the method comprising the steps of;
i) preparing a gas diffusion electrode according to the method of claim 12 ;
ii) applying the gas diffusion electrode prepared in step i) to a face of an ion-conducting membrane.
14. A method of preparing a catalysed decal transfer substrate, the method comprising applying an electrocatalyst layer to a substrate according to the method of claim 11 , wherein the substrate is a face of a decal transfer substrate.
15. A method of preparing a catalyst coated ion-conducting membrane, the method comprising preparing a catalysed decal transfer substrate according to the method of claim 14 and applying an electrocatalyst layer to an ion-conducting membrane by decal transfer from the catalysed decal transfer substrate.
16. A method of preparing a membrane electrode assembly, the method comprising the steps of;
i) preparing a catalyst coated ion-conducting membrane according to the method of claim 15 ;
ii) applying a gas diffusion layer to the electrocatalyst layer.
17. A method of preparing a catalyst coated ion-conducting membrane, the method comprising applying an electrocatalyst layer to a substrate according to the method of claim 11 , wherein the substrate is a face of an ion-conducting membrane.
18. A method of preparing a membrane electrode assembly, the method comprising the steps of,
i) preparing a catalyst coated ion-conducting membrane according to the method of claim 17 ;
ii) applying a gas diffusion layer to the electrocatalyst layer.