Carbon supported platinum is commonly used as anode and cathode electrocatalyst in low-temperature fuel cells fuelled with hydrogen or low molecular weight alcohols. The cost of Pt and the limited world supply are significant barriers to the widespread use of these types of fuel cells. Moreover, platinum used as anode material is readily poisoned by carbon monoxide, present in the reformate gas used as H2 carrier in the case of polymer electrolyte fuel cells, and a byproduct of alcohol oxidation in the case of direct alcohol fuel cells. In addition, Pt alone does not present satisfactory activity for the oxygen reduction reaction when used as cathode material. For all these reasons, binary and ternary platinum-based catalysts and non-platinum-based catalysts have been tested as electrode materials for low temperature fuel cells. Palladium and platinum have very similar properties because they belong to the same group in the periodic table. The activity for the oxygen reduction reaction (ORR) of Pd is only slightly lower than that of Pt, and by addition of a suitable metal, such as Co or Fe, the ORR activity of Pd can overcome that of Pt. Conversely, the activity for the hydrogen oxidation reaction (HOR) of Pd is considerably lower than that of Pt, but by adding of a very small amount (5 at%) of Pt, the HOR activity of Pd attains that of pure Pt. This paper presents an overview of Pd and Pd-containing catalysts, tested both as anode and cathode materials for low-temperature fuel cells.

Palladium in fuel cell catalysis

▪ Abstract After a brief survey of fuel cell types, attention is focused on material requirements for SOFC and PEMFC stacks, with an introductory section on materials technology for reformers. Materials cost and processing, together with durability issues, are emphasized as these now dominate materials selection processes for prototype stack units. In addition to optimizing the cell components, increasing attention is being given to the composition and processing of the bipolar plate component as the weight and volume of the relevant material has a major influence on the overall power density and cost of the fuel cell stack. It is concluded that the introduction of alternative materials/processes that would enable PEMFC stacks to operate at 150–200°C, and IT-SOFC stacks to operate at 500–700°C, would have a major impact on the successful commercialization of fuel cell technology.

Recent Advances in Materials for Fuel Cells

The stability of Pt–M (M = first row transition metal) alloy catalysts and its effect on the activity in low temperature fuel cells: A literature review and tests on a Pt–Co catalyst

In recent years there has been much activity in examining Pt alloys with first row transition metals as catalysts materials for DMFCs In this work, the electrochemical oxidation of methanol on Pt–Co and –Ni alloy electrocatalysts is reviewed The effect of the transition metal on the electrocatalytic activity of Pt–Co and –Ni for the methanol oxidation reaction (MOR) has been investigated both in half-cell and in direct methanol fuel cells Conflicting results regarding the effect of the presence of Co(Ni) on the MOR are examined and the primary importance of the amount of non-precious metal in the catalyst is remarked For low base metal contents, an enhancement of the onset potential for the MOR with increasing Co(Ni) amount in the catalyst is observed, whereas for high contents of the base metal, a drop of the MOR onset potential with increasing Co(Ni) is found As well as the base metal content, an important role on the MOR activity of these catalysts has to be ascribed to the degree of alloying

The methanol oxidation reaction on platinum alloys with the first row transition metals The case of Pt-Co and -Ni alloy electrocatalysts for DMFCs: A short review

Some general principles for designing electrocatalysts with hydrogenase activity

Industrial application of fuel cell technology requires suitable electrocatalysts. This is true for all different types of fuel cells. These catalysts are responsible for the oxidation of the fuel (i.e. hydrogen, hydrogen rich gases or methanol) as well as for the oxygen reduction. This paper focuses on solid polymer electrolyte fuel cell systems for mobile applications. Here the demands on the catalyst are most severe due to the low-temperature operating regime. Two system configurations are possible: either the carbon containing fuel is processed by a fuel converter to a hydrogen rich gas mixture and this in turn is fed into the fuel cell. Alternatively fuels such as methanol can be supplied directly into the fuel cell. In the first case, contaminations of CO in the feed gas have to be taken into account. These strongly absorbs on the surface of the catalysts (carbon-supported Pt or Pt-alloys) thereby inhibiting the hydrogen oxidation reaction. Electro-oxidation mechanisms of adsorbed CO as well as methanol—as an example for a direct fuel cell system—is discussed on Pt-Ru and other catalysts. Finally catalysts for methanol and hydrocarbon reforming reactions as well as for the shift reaction are reviewed.

Catalytic processes in solid polymer electrolyte fuel cell systems

A process for producing a catalytic converter utilizes deposition of a catalytically active material electrochemically deposited on a substrate as aresult of the substrate being immersed in an electrolyte, which contains the catalytically active material, and an electric voltage being applied between the substrate and a counterelectrode. The platinum is deposited on a metallic substrate from a platinum-containing sulphuric acid solution, or in which process a Pt/Ru mixture is deposited on a metallic substrate from a sulphuric acid solution containing platinum and ruthenium as catalytically active material, which a Pt:Ru ratio of from 1:10 to 1:20.

Process for producing a catalytic converter and catalytic converter made by said process

Production of a metallized electrode comprises applying a catalyst onto a conducting substrate coated with a polymer by electrochemical deposition. Before the electrochemical deposition, an acidic metal salt solution is electromagnetically irradiated. Deposition is carried out through the polymer. Preferred Features: The carbon-containing substrate has two or more layers. Irradiation is carried out for 20 seconds to 3 hours. The metal salt complexes are partially and/or completely hydrated after the electromagnetic irradiation. Platinum complexes, preferably hexachloroplatinic (IV) acid, are used as the starting material for the production of the catalyst.

Production of a metallized electrode used as a gas diffusion electrode for a polymer-electrolyte-membrane fuel cells comprises applying a catalyst onto a conducting substrate coated with a polymer by electrochemical deposition

The invention relates to a method for preparing a catalyst wherein a catalytically active material is electrochemically deposited on a substrate by the substrate is immersed in an electrolyte which contains the catalytically active material and an electric voltage between the substrate and a counter electrode is applied, that platinum is deposited on a metallic substrate composed of a platinum-containing sulfuric acid solution, or that of a sulfuric acid solution containing platinum and ruthenium as the catalytically active material having a ratio of Pt: Ru 1:10 to 1:20, a Pt / Ru mixture on a metallic substrate is deposited.

Anett Funke

Papers

Catalytic processes in solid polymer electrolyte fuel cell systems

Process for producing a catalytic converter and catalytic converter made by said process

Production of a metallized electrode used as a gas diffusion electrode for a polymer-electrolyte-membrane fuel cells comprises applying a catalyst onto a conducting substrate coated with a polymer by electrochemical deposition

Electrochemical process for producing a catalyst

Developing an innovative and high-performance method for recovering reusable launcher stages: the in-air capturing method