Precious metal oxide catalyst for water electrolysis

The invention is directed to precious metal oxide catalysts, particularly to iridium oxide based catalysts for use as anode catalysts in PEM water electrolysis and other applications. The composite catalyst materials comprise iridium oxide (IrO 2 ) and optionally ruthenium oxide (RuO 2 ) in combination with an inorganic oxide (for example TiO 2 , Al 2 O 3 , ZrO 2 and mixtures thereof). The inorganic oxide has a BET surface area in the range of 30 to 200 m 2 /g and is present in a quantity of 25 to 70 wt.-% based on the total weight of the catalyst. The catalyst materials are characterised by a good electrical conductivity > 0.01 S/cm and high current density. The catalysts are used in electrodes, catalyst-coated membranes and membrane-electrode-assemblies for PEM electrolyzers, PEM fuel cells, regenerative fuel cells (RFC), sensors and other electrochemical devices.