Understanding the Crucial Significance of the Temperature and Potential Window on the Stability of Carbon Supported Pt-Alloy Nanoparticles as Oxygen Reduction Reaction Electrocatalysts.

Tina Đukić,Mitja Kostelec,Matija Gatalo,Goran Dražić,Martin Prokop,Nejc Hodnik,Martin Šala,Leonard Jean Moriau,Francisco Ruiz-Zepeda,Luka Pavko

doi:10.1021/acscatal.1c04205

Abstract

The present research provides a study of carbon-supported intermetallic Pt-alloy electrocatalysts and assesses their stability against metal dissolution in relation to the operating temperature and the potential window using two advanced electrochemical methodologies: (i) the in-house designed high-temperature disk electrode (HT-DE) methodology as well as (ii) a modification of the electrochemical flow cell coupled to an inductively coupled plasma mass spectrometer (EFC-ICP-MS) methodology, allowing for highly sensitive time- and potential-resolved measurements of metal dissolution. While the rate of carbon corrosion follows the Arrhenius law and increases exponentially with temperature, the findings of the present study contradict the generally accepted hypothesis that the kinetics of Pt and subsequently the less noble metal dissolution are supposed to be for the most part unaffected by temperature. On the contrary, clear evidence is presented that in addition to the importance of the voltage/potential window, the temperature is one of the most critical parameters governing the stability of Pt and thus, in the case of Pt-alloy electrocatalysts, also the ability of the nanoparticles (NPs) to retain the less noble metal. Lastly, but also very importantly, results indicate that the rate of Pt redeposition significantly increases with temperature, which has been the main reason why mechanistic interpretation of the temperature-dependent kinetics related to the stability of Pt remained highly speculative until now.

Highlights

In humanity’s goal to become a carbon-neutral society, mass adoption of hydrogen as the energy carrier and proton exchange membrane fuel cells (PEMFCs) as the energy production technology are becoming recognized as one of the most important pieces of the puzzle in the fight against the negative impacts of climate change.[1−3] In PEMFCs, hydrogen as a fuel and oxygen from the air are converted into clean electricity with water as the only byproduct
Prior to the interpretation of the results presented as part of the stability study, it is important to state that the main goal of this work was to investigate the stability of the ReCatalyst intermetallic Pt−Co/C electrocatalyst while obtaining the understanding related to the effects of both the temperature and the potential window
While the rate of carbon corrosion follows the Arrhenius law and increases exponentially with temperature, the findings of the present study contradict the generally accepted hypothesis that the kinetics of Pt and subsequently the less noble metal dissolution are supposed to be for the most part unaffected by temperature.[81]

Summary

Introduction

In humanity’s goal to become a carbon-neutral society, mass adoption of hydrogen as the energy carrier and proton exchange membrane fuel cells (PEMFCs) as the energy production technology are becoming recognized as one of the most important pieces of the puzzle in the fight against the negative impacts of climate change.[1−3] In PEMFCs, hydrogen as a fuel and oxygen from the air are converted into clean electricity with water as the only byproduct This makes PEMFCs especially suitable for competing with and eventually replacing conventional internal combustion engines (ICEs) in transport related applications. According to the existing evidence,[7] mass commercialization of PEMFC technology will not be possible

Objectives

Results

Conclusion