Performance and degradation studies of RuO2–Ta2O5 anode electrocatalyst for high temperature PBI based proton exchange membrane water electrolyser

Ruthenium oxide-tantalum oxide (RuO2–Ta2O5) anode electrocatalysts are prepared with different compositions by sol–gel procedure and employed in half cell and high temperature proton exchange water electrolyser (PEMWE) to study oxygen evolution reaction (OER), performance and stability of the catalyst in PEMWE. Physical characterization of RuO2–Ta2O5 by energy dispersive X-ray (EDX) shows presence of no impurity. X-ray diffraction (XRD) analysis of different compositions of RuO2–Ta2O5 reveals that addition of Ta2O5 to RuO2 upto 10% results in solid solution and beyond 10% Ta2O5, RuO2 and Ta2O5 maintain their phases. XRD and transmission electron microscopy (TEM) reveals uniform formation of RuO2–Ta2O5 particles with a size of 10–15 nm. Electrochemical characterization carried out by cyclic voltammetry for different ratios of RuO2–Ta2O5 catalysts in 1.0 M H3PO4 electrolyte gives maximum current density of 17.27 mA cm−2 at 1.2 V for 90%RuO2–10%Ta2O5 anode catalyst at 90 °C. Linear sweep voltammetry of 90%RuO2–10%Ta2O5 using rotating ring disk electrode at different rotations (800–2000 rpm) indicates high activity towards OER. The prepared RuO2–Ta2O5 anode electrocatalysts tested in the high temperature (150 °C) PEMWE using H3PO4 doped polybenzimidazole membrane as an electrolyte and Pt black as cathode gives best performance for 90%RuO2–10%Ta2O5 electrocatalyst with current density of 1.1 A cm−2 at 1.8 V. Moreover, 90%RuO2–10%Ta2O5 anode catalyst found to be more stable compared to RuO2 in 5 h operation of PEMWE at 150 °C. To gauge degradation process in PEMWE, anolyte and membrane electrode assembly are examined by fourier transform infrared (FTIR) and X-ray photoelectron spectroscopies (XPS) after PEMWE operation.