Synthesis and characterization of electrocatalysts for the oxygen evolution in PEM water electrolysis
Abstract
IrO$_2$, Ir$_x$Sn$_{(1−x)}$O$_2$ (x = 0.7, 0.5) and Ir$_x$Ru$_{(1−x)}$O$_2$ (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 cm$^2$ proton-exchange membrane water electrolysis cell. An increase of the electrical performance was observed upon Ru insertion and a severe depreciation upon Sn insertion.