Fuel cell or electrolyser

A method of constructing a fuel cell or an electrolyser comprising:

• providing a cathode comprising a catalyst system comprising a carrier metal oxide and a catalyst material, the providing of the cathode including mixing the carrier metal oxide and the catalyst material together to form a powder mixture in which an electrically conductive metal phosphate is adsorbed as the catalyst material on a surface of the carrier metal oxide, and depositing the mixed carrier metal oxide and catalyst material on a carrier plate, the electrically conductive metal phosphate being in the form of a metaphosphate of the general chemical formula Mezn+2(PnO3n+1)z, where
• Me=a metal,
• z=a valency of the metal Me, and
• n is within a range of 1 to 10;
• and
• arranging a polymer electrolyte membrane adjacent to the cathode;
• and
• after the mixing of the carrier metal oxide and the catalyst material together to form the powder mixture, applying a dopant by means of a sputtering process to the powder mixture.