Preparation of ruthenium oxide catalyst for oxygen evolution reaction in HT-PAWE by pulsed electrodeposition

Despite the fact that the technique of proton exchange membrane water electrolysis (PEMWE) dominates the market because of its low temperature of operation, platinum as a catalyst renders it relatively expensive. In this work, we demonstrated a recyclable ruthenium catalyst with high stability, high oxygen evolution reaction (OER) performance and low onset potential. In particular, instead of PEMWE, the technique of high temperature phosphoric acid water electrolysis (HT-PAWE) was used, with ruthenium oxide as its anode catalyst and a high operation temperature to decrease the amount of noble metals being used. Ruthenium was chosen in this study due to its excellent catalytic activity. The possibility of recycling and reusing noble metals would ease the problem of high cost. Homemade ruthenium catalyst in this study exhibited an outstanding OER performance including high stability and high current density than those of commercial platinum catalyst. Linear sweep voltammetry (LSV) test results showed that a maximum current density of 190 mA/cm2 was reached at only 1.5VSCE. For this experiment, ruthenium (III) chloride hydrate (RuCl3·3H2O) was used as the precursor, and potassium chloride (KCl) and hydrochloric acid (HCl) acted as the supporting electrolyte. Pulsed electrodeposition was chosen to achieve a better control in particle size and distribution of the catalyst over selected specimens. After electrodeposition, the specimens underwent thermal treatment for increasing stability in catalyst particles. Scanning electron microscopy (SEM), linear sweep voltammetry (LSV) and cyclic voltammetry (CV) were used to observe the morphology and to analyze the OER performance of the specimens, respectively. Types of catalyst carrier, electrodeposition potential and duration, and thermal treatment temperature were studied. As a result, all four parameters affected the morphologies and electrochemical performances of the tested specimens.