Catalytic composition, method for production thereof, use thereof for producing a fuel cell electrode and fuel cell comprising same
A catalytic composition for producing a fuel cell electrode comprises a catalytically active material in particulate form, for example platinum, a carbon nanomaterial which is coated with a first ionomer, as well as a binding agent composition in which the catalytically active material and the coated carbon nanomaterial are present in dispersed form, wherein the binding agent composition comprises a second ionomer and the first and second ionomers are the same or different. The composition is used to produce a catalytic layer of a fuel cell electrode for a fuel cell.
1 . A method for producing a catalytic composition, comprising:
a first stage of forming an ionomer-encapsulated carbon nanomaterial that is free of noble metal catalytically active material, the first stage including mixing a carbon nanomaterial with a first ionomer having a first equivalent mass in a solvent and exposing the mixture to predetermined temperature and pressure conditions to form the ionomer-encapsulated carbon nanomaterial;
drying the ionomer-encapsulated carbon nanomaterial; and
a second stage of mixing components of the catalytic composition, including mixing the ionomer-encapsulated carbon nanomaterial with noble metal catalytically active material in particulate form and a binding agent composition that comprises a second ionomer having a second equivalent mass greater than the first equivalent mass of the first ionomer of the ionomer-encapsulated carbon nanomaterial, wherein the first equivalent mass of the first ionomer of the ionomer-encapsulated carbon nanomaterial is less than the second equivalent mass of the second ionomer, and wherein the noble metal catalytically active material and the ionomer-encapsulated carbon nanomaterial are independent components in the binding agent composition.
2 . The method according to claim 1 , wherein the predetermined temperature conditions comprise a temperature in the range of 40 to 150° C.
3 . The method according to claim 1 , wherein the predetermined pressure conditions comprise a pressure in the range of ambient pressure to 1050 kPa.
4 . The method according to claim 1 , wherein the solvent is an alcohol, water, or a mixture of alcohol and water.
5 . A method, comprising:
producing the catalytic composition according to claim 1 ; and
producing a catalytic layer of a fuel cell electrode using the catalytic composition.
6 . The method according to claim 1 , wherein the first ionomer has an equivalent mass smaller than 850.
7 . The method according to claim 1 , wherein the ionomer-encapsulated carbon nanomaterial has an average layer thickness of the first ionomer on the carbon nanomaterial of 8 to 12 nm.
8 . The method of claim 1 , wherein the ionomer-encapsulated carbon nanomaterial has an average layer thickness of the first ionomer on the carbon nanomaterial of 5 to 20 nm.
9 . The method of claim 1 , wherein the noble metal catalytically active material is supported on a carbon support.
10 . The method of claim 9 , wherein the carbon support is made of a carbon nanomaterial.
11 . The method of claim 10 , wherein the binding agent composition comprising the second ionomer, coats the noble metal catalytically active material that is supported on the carbon support and coats the ionomer-encapsulated carbon nanomaterial.