"Unraveling the Secret Behind Fuel Cell Catalyst Lifespan Reduction: First Atomic-Level Identification"

Joint Research by KENTECH and POSTECH
A Turning Point in the Development of High-Performance Energy Materials

A joint research team from Korea Institute of Energy Technology (KENTECH) and Pohang University of Science and Technology (POSTECH) has revealed, at the atomic level, the reason why the performance of next-generation fuel cell catalysts degrades over time.

The team successfully tracked, in real time, the entire process from the formation of nanoparticles to their eventual collapse after prolonged use. This achievement is considered a turning point for the development of high-performance and highly durable energy materials in the future.

This research was jointly conducted by Professor Sangho Oh’s team at KENTECH and Professor Hyun Han’s team at POSTECH.

They focused on metallic nanoparticle catalysts formed through the 'exsolution' method. Exsolution refers to a phenomenon in which metal inside an oxide migrates to the surface under a high-temperature reducing environment, spontaneously forming nanoparticles. Compared to conventional deposition methods, these nanoparticles are more firmly anchored to the support, resulting in higher stability.

Schematic diagram showing the formation of eluted nanoparticles, healing of crystal defects, and the degradation process characterized by surface depression and secondary phase formation after prolonged reaction.
[Photo by Korea University of Science and Technology]

The researchers directly observed the entire process, from nanoparticle formation to degradation, using real-time transmission electron microscopy. As a result, they found that, in the initial stages, nickel (Ni) nanoparticles rose to the surface while 'anti-phase boundary (APB)' defects disappeared simultaneously.

This demonstrates that exsolution is a complex process involving not only simple particle formation but also crystal structure rearrangement and defect healing.

However, the situation changed under prolonged high-temperature reduction conditions. Nickel and strontium (Sr) gradually dissipated, causing micro-depressions to form on the surface, followed by the emergence of secondary phases and subsequent structural collapse.

The research team explained this as a continuous process of 'structural equilibrium, re-imbalance, and decomposition.'

This study proved that catalyst performance degradation is not simply due to particle growth or agglomeration, but is the result of a complex interplay of changes in crystal defects, elemental loss, surface structure deformation, and secondary phase formation.

In particular, it clearly highlighted the need to consider not only the initial activity of catalysts but also their long-term stability in design.

Professor Sangho Oh stated, "The significance of this research lies in directly identifying the causes of exsolution catalyst degradation at the atomic level." Professor Hyun Han also expressed hope, saying, "We expect this achievement to lead to new strategies for designing high-performance and highly durable catalysts."

The results of this study were published in 'ACS Nano,' a prestigious journal in the field of nanoscience.

This content was produced with the assistance of AI translation services.