Anodic characteristics of amorphous ternary palladium-phosphorus alloys containing ruthenium, rhodium, iridium, or platinum in a hot concentrated sodium chloride solution

Abstract

Amorphous ternary palladium-based alloys containing platinum group metals as an additional element were prepared by rapid quenching from the molten state and their anodic characteristics were investigated in a 4 mol dm⁻³ NaCl solution of pH 4 and 80° C. The amorphous alloys containing sufficient quantities of rhodium, platinum or iridium were passivated by anodic polarization and their corrosion rates at high current densities in the chlorine evolution region were extremely low. This fact was attributed to the formation of a highly protective passive film due to both the transformation to the amorphous structure and the addition of rhodium, platinum or indium. The electrocatalytic activities for chlorine evolution of amorphous alloys were higher than those of pure platinum group metals except palladium. In particular, the amorphous Pd₄₁Ir₄₀P₁₉ alloy had the desired stable, high electrocatalytic activity for chlorine evolution and the high overvoltage for oxygen evolution.