KU–KBSI-UNIST research team develops high-performance electrode catalysts for water-splitting

Results published in leading journal Advanced Materials


▲ Dr. Aram Oh, Ho Young Kim, Dr. Hionsuck Baik, Prof. Sang Hoon Joo, Prof. Kwangyeol Lee (from left)

 

 

Water electrolysis technology, which breaks down water to obtain hydrogen, is recognized as a clean technology that does not produce carbon dioxide or other pollutants. In particular, water electrolysis in acidic media has come under the spotlight for its high activity. However, the high cost and low durability of the iridium or ruthenium catalysts are obstacles to commercialization, but have been overcome thanks to a new electrode catalyst developed by a local research team.

 

The team, comprised of members of Korea University (Prof. Kwangyeol Lee, Department of Chemistry), the Korea Basic Science Institute (Aram Oh and Hionsuck Baik), and the Ulsan National Institute of Science and Technology (Prof. Sang Hoon Joo and Ho Young Kim), fabricated a Pt/Ni/Ru nanocrystal, and utilized it as an electrode catalyst for water electrolysis in acidic media. With this proposed nanocrystal electrode catalyst, they succeeded in achieving the world best standard of activity and durability for water-splitting electrode catalysts.

 

The team fabricated a core double-shell icosahedral Pt/Ni/Ru nanocrystal by applying phase dissociation to a nanoparticle alloy comprised of multiple elements, and examined the structure and composition of the nanoparticles through double modified aberration-corrected transmission electron microscopy. After acid and heat treatment, they produced a new type of nanocrystal, consisting of a Ni/Ru-doped Pt core and a Pt/Ni-doped RuO2 frame shell.

 

The proposed nanocatalyst featured catalytic activity 15 times higher than current commercial iridium catalysts. While commercial iridium catalysts only managed to retain 40% of their initial performance after 10 hours of operation, the proposed catalyst retained 90%, demonstrating its durability.

 

The core and frame shell structure of the proposed catalysts minimizes the use of expensive metal, and has optimal area for high catalytic activity. Through the synergistic Pt/Ni/Ru relationship, the team achieved the world’s highest activity and durability for water electrolysis reactions. They were also able to examine the mechanism behind the formation of frame-type nanoparticles using the high spatial resolution (60 pm) transmission electron microscope owned by the Seoul center of KBSI.

 

Professor Kwangyeol Lee said, “To commercialize this technology, we are conducting follow-up studies on the mass production of catalysts, and the extension of stable operation time. The catalytic activity and improved durability of unstable metal oxides doped with other elements can be applied to various catalytic systems related to energy and the environment, and thereby play a part in overcoming environmental issues.” Professor Sang Hoon Joo of UNIST said, “Further research will be conducted to study the principles behind the improved catalytic activity and durability of the new catalyst.”

 

Supported by the National Research Foundation of Korea and KBSI, the study was published in the online version of Advanced Materials, a leading journal in nanoscience, chemistry and materials science, on October 26 under the title of “Topotactic Transformations in an Icosahedral Nanocrystal to Form Efficient Water‐Splitting Catalysts.”

 

[Fig. 1]

TEM image of the high-performance Pt/Ni/Ru nanocatalyst, and a schematic evaluating the performance of the electrode catalyst for water electrolysis


[Fig. 2]

Schematic of water electrolysis