Synthesis and characterization of electrocatalysts for the oxygen evolution in PEM water electrolysis

IrO₂, Ir_xSn_(1−x)O₂ (x = 0.7, 0.5) and Ir_xRu_(1−x)O₂ (x = 0.7, 0.5) electrocatalysts for the oxygen evolution reaction (OER) have been synthesized using the Adams fusion method. The metal oxides were characterized via X-ray diffraction, scanning electron microscopy, inductively coupled plasma-atomic emission spectrometry and nitrogen adsorption-desorption measurements to have information about their crystallographic structure, chemical composition and morphology, respectively. A controlled bulk molar fraction of Ru or Sn was introduced in the IrO₂ lattice during the synthesis with no phase separation. The electrocatalytic activity of the synthesized oxides in the OER was studied in liquid electrolyte using porous rotating-disk electrodes, in “half-cell” configuration and in a 5 cm² proton-exchange membrane water electrolysis cell. An increase of the electrical performance was observed upon Ru insertion and a severe depreciation upon Sn insertion.