Stability of Supported Pd-based Ethanol Oxidation Reaction Electrocatalysts in Alkaline Media

TL;DR

This study assesses the dissolution stability of various Pd-based catalysts during ethanol oxidation in alkaline media, highlighting the importance of additive stability for fuel cell applications.

Contribution

It introduces a comprehensive evaluation of Pd-based catalysts' stability using advanced in-situ and ex-situ techniques, emphasizing the role of metal additives.

Findings

Sn and Fe additives improve catalyst activity and stability

Nb dissolution destabilizes Pd, increasing leaching

Additive stability is crucial in catalyst design

Abstract

This study evaluates the dissolution of the supported electrocatalysts Pd/C, PdSn/C, PdNb/C, and PdFe3O4/C during ethanol oxidation reaction for ADLFC applications. A scanning flow cell (SFC) coupled to an inductively coupled mass spectrometry (online ICP-MS) is used to assess the dissolution stability in a broad potential window. Accelerated stress tests with and without ethanol are developed using a rotating disk electrode (RDE) with dissolution products analysis by ex-situ ICP-MS. Potential profiles simulating those experienced by the catalyst during regular fuel cell operation were used. Sn and Fe catalysts demonstrate improved activity and stability compared with the material with Pd alone. For these reasons, PdSn/C and PdFe3O4/C are suitable for ADLFC applications. Severe Nb dissolution destabilizes Pd, increasing its leaching. This work demonstrates that while additional metals and oxides can improve the alcohol oxidation kinetics of Pd, these additives' dissolution stability must already be considered at the catalyst design stage.