A perspective on the promoting effect of Ir and Au on Pd toward the ethanol oxidation reaction in alkaline media

Abstract

There remain great challenges in developing highly efficient electrocatalysts with both high activity and good stability for the ethanol oxidation reaction in alkaline media. Herein, two architectures of tri-metallic PdIrAu/C electrocatalysts are designed and the promoting effect of Au and Ir on Pd toward the ethanol oxidation reaction (EOR) in alkaline media is investigated in detail. On the one hand, the tri-metallic Pd7Au7Ir/C electrocatalyst with a solid solution alloy architecture is less active relative to Pd7Ir/C and Pd/C while the stabilizing effect of Au leads to both a higher activity and a lower degradation percentage after 3000 cycles of the accelerated degradation test (ADT) on Pd7Au7Ir/C than those on Pd7Ir/C. On the other hand, the tri-metallic Pd7Ir@(1/3Au)/C electrocatalyst with a near surface alloy architecture delivers a much higher activity with an improvement up to 50.4% compared to Pd7Ir/C. It is speculated that for the tri-metallic Pd7Ir@(1/3Au)/C electrocatalyst, certain Au atoms are well designed on surfaces to introduce an electronic modification, thus leading to an anti-poisoning effect and improving the EOR activity.