Gas diffusion electrode and process for production thereof
The present invention relates to a gas diffusion electrode that includes an electrically conductive carrier, and a porous coating based on an electrochemically active catalyst and a hydrophobic material, wherein the electrode has a first side facing an oxygen-containing gas and a second side facing an alkaline electrolyte, wherein the catalyst comprises a noble metal as a catalytically active component, wherein the hydrophobic material comprises a hydrophobic polymer, and wherein the coating comprising the catalyst has a pore volume from 10 to 500 mm 3 /g, and a pore diameter in the range from 100 to 10,000 nm.
1. A gas diffusion electrode comprising
an electrically conductive carrier, and
a porous coating based on an electrochemically active catalyst and a hydrophobic material,
wherein the electrode has a first side-facing an oxygen-containing gas and a second side facing a liquid alkaline electrolyte,
wherein the catalyst comprises a noble metal as a catalytically active component,
wherein the hydrophobic material comprises a hydrophobic polymer, wherein the hydrophobic polymer comprises polytetrafluoroethylene (PTFE), and
wherein the coating comprising the catalyst has a pore volume from 50 to 200 mm 3 /g, and a pore diameter in the range from 100 to 10,000 nm.
2. The gas diffusion electrode according to claim 1 , wherein the noble metal is silver or platinum.
3. The gas diffusion electrode according to claim 1 , wherein the coating comprising the catalyst has a pore diameter from 600 to 6,000 nm.
4. The gas diffusion electrode according to claim 1 , wherein the coating has a unimodal pore distribution.
5. The gas diffusion electrode according to claim 1 , wherein the coating comprising the catalyst has a porosity from 10 to 70%.
6. The gas diffusion electrode according to claim 1 , wherein the coating comprising the catalyst has a porosity from 20 to 60%.
7. The gas diffusion electrode according to claim 1 , wherein the coating comprising the catalyst has a thickness from 20 to 1,000 μm.
8. The gas diffusion electrode according to claim 1 , wherein the coating comprising the catalyst has a thickness from 200 to 600 μm.
9. The gas diffusion electrode according to claim 1 , wherein the electrode has a total loading of the catalytically active component within a range from 5 mg/cm 2 to 300 mg/cm 2 .
10. The gas diffusion electrode according to claim 1 , wherein the electrode has a total loading of the catalytically active component within a range from 10 mg/cm 2 to 250 mg/cm 2 .
11. The gas diffusion electrode according to claim 1 , wherein the carrier is based on nickel, silver or a mixture thereof.
12. The gas diffusion electrode according to claim 1 , wherein the carrier is in the form selected from the group consisting of a mesh fabric, a woven fabric, a knitted fabric, a nonwoven fabric, an expanded metal, or a foam.
13. The gas diffusion electrode according to claim 1 , wherein the carrier is in the form of a woven fabric.
14. A chloralkali electrolysis apparatus comprising the gas diffusion electrode according to claim 1 as an oxygen-consuming cathode.
15. A fuel cell comprising the gas diffusion electrode according to claim 1 .
16. A metal/air battery comprising the gas diffusion electrode according to claim 1 .
17. A gas diffusion electrode comprising
an electrically conductive carrier, and
a porous coating based on an electrochemically active catalyst and a hydrophobic material,
wherein the electrode has a first side facing an oxygen-containing gas and a second side facing a liquid alkaline electrolyte,
wherein the catalyst comprises a noble metal as a catalytically active component,
wherein the hydrophobic material comprises a hydrophobic polymer, wherein the hydrophobic polymer comprises polytetrafluoroethylene (PTFE), and
wherein the coating comprising the catalyst has a pore volume from 78 to 115 mm 3 /g, and a mean pore diameter in the range from 2,096 to 3,042 nm.
18. A gas diffusion electrode consisting of
an electrically conductive carrier, and
a porous coating based on an electrochemically active catalyst and a hydrophobic material,
wherein the electrode has a first side facing an oxygen-containing gas and a second side facing a liquid alkaline electrolyte,
wherein the catalyst comprises a noble metal as a catalytically active component,
wherein the hydrophobic material comprises a hydrophobic polymer, wherein the hydrophobic polymer comprises polytetrafluoroethylene (PTFE), and
wherein the coating comprising the catalyst has a pore volume from 50 to 200 mm 3 /g, and a pore diameter in the range from 100 to 10,000 nm.
19. The gas diffusion electrode according to claim 1 , wherein the liquid alkaline electrolyte is a sodium hydroxide solution.
20. The gas diffusion electrode according to claim 18 , wherein the liquid alkaline electrolyte is a sodium hydroxide solution.