(IrOx – Pt)/Ti bifunctional electrodes for oxygen evolution and reduction

Abstract

Mixed Ir–Pt electrocatalytic films on Ti metal supports were prepared via a galvanic deposition process. Two types of (Ir – Pt)/Ti electrodes were prepared with different Ir–Pt compositions (Ir/Pt atomic composition ratios of 1.74 and 0.44, based on ICP-MS measurements) and of a similar total metal loading (0.15 and 0.12 mg cm−2). The simultaneous deposition of both metallic Ir and Pt occurred spontaneously upon immersion of a freshly etched Ti metal substrate into a composite solution of Ir(IV) and Pt(IV) complexes of variable concentration. This was followed by electrochemical anodization to convert Ir to IrOx. Both electrodes showed homogeneous Ir and Pt dispersion on the Ti surface. The bifunctional electrocatalytic performance of (IrOx/Ir – Pt)/Ti electrodes has been tested towards the oxygen evolution (OER) and reduction (ORR) reactions in acidic solutions. The thus prepared Ti-supported Ir–Pt film electrodes exhibited satisfactory performance towards both reactions, with mass-specific currents for OER being higher than those at a single component IrOx/Ir/Ti electrode and the ones for ORR being comparable to those at a single component Pt/Ti electrode.