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

IrO2, IrxSn(1−x)O2 (x = 0.7, 0.5) and IrxRu(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.

► IrO2, IrxSn(1−x)O2 (x = 0.7,0.5) and IrxRu(1−x)O2 (x = 0.7,0.5) catalysts for OER. ► Characterizations via XRD, SEM, ICP–AES and N2 adsorption–desorption were realized. ► Controlled fractions of Ru or Sn were introduced in the IrO2 lattice. ► OER characterizations were performed in different scales (RDE, half cell, cell). ► Best electrical performances were obtained upon Ru insertion.