Nanosized IrxRu1−xO2 electrocatalysts for oxygen evolution reaction in proton exchange membrane water electrolyzer

Hong Hanh Pham, Ngoc Phong Nguyen, Chi Linh Do and Ba Thang Le

Abstract

Normally in proton exchange membrane water electrolysis (PEMWE), the anode has the largest overpotential at typical operating current densities. By development of the electrocatalytic material used for the oxygen evolving electrode, great improvements in efficiency can be performed. In electrochemistry, rare metallic oxides RuO₂ and IrO₂ exhibit the best catalytic properties for the oxygen evolution reaction (OER) in acid electrolytes compared to other noble metals. RuO₂ is the most active catalyst and IrO₂ is the most stable catalyst. An oxide containing both elements is therefore expected to be a good catalyst for the OER. In this study Ir_xRu_1−xO₂ nanosized powder electrocatalysts for oxygen evolution reaction is synthesized by hydrolysis method. Cyclic voltammetry, anodic polarization and galvanostatic measurements were conducted in solution of 0.5 M H₂SO₄ to investigate electrocatalytic behavior and stability of the electrocatalyst. The mechanisms of the thermal decomposition process of RuCl₃.nH₂O and IrCl₃.mH₂O precursors to form oxide powders were studied by means of thermal gravity analysis (TGA). X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used analysis for determination of the crystallographic structure, morphology and catalysts particle size. Based on the given results, the Ir_xRu_1−xO₂ (x = 0.5; 0.7) compounds were found to be more active than pure IrO₂ and more stable than pure RuO₂