Paving the Way for Efficient Hydrogen Production: Insights into Catalyst Development

Recent research in the realm of catalyst development for hydrogen production has made significant strides, offering promising directions for future advancements. A collaborative effort between Professor Yong-Tae Kim from the Department of Materials Science and Engineering and the Graduate Institute of Ferrous & Eco Materials Technology, and Kyu-Su Kim, a doctoral student from the Department of Materials Science and Engineering at Pohang University of Science and Technology (POSTECH), has resulted in a breakthrough study featured as the cover article in ACS Catalysis.

Hydrogen production through water electrolysis has emerged as an environmentally friendly and sustainable technology, with the potential to generate hydrogen from the abundant resource of water without emitting carbon dioxide. However, the reliance on precious metal catalysts like iridium (Ir) has presented economic challenges. To address this issue, researchers are actively exploring the development of catalysts in the form of metal alloys.

In the field of water electrolysis catalysis, iridium, ruthenium (Ru), and osmium (Os) are among the primary catalysts under investigation. While iridium offers high stability, it exhibits relatively low activity and comes with a high cost. In contrast, ruthenium displays commendable activity and is more cost-effective than iridium, though it lacks the same level of stability. Osmium, however, dissolves under various electrochemical conditions, leading to the formation of nanostructures that expand the electrochemical active surface area and enhance geometrical activity.

The research team initially developed catalysts by combining iridium and ruthenium, effectively preserving the favorable attributes of each metal. These hybrid catalysts exhibited improvements in both activity and stability. Catalysts incorporating osmium displayed high activity due to the expanded electrochemical active surface area achieved through nanostructure formation while retaining the advantageous properties of iridium and ruthenium.

Subsequently, the team expanded their experimentation to include all three metals. The results showed a moderate increase in activity, but the dissolution of osmium had a detrimental effect, significantly compromising the structural integrity of iridium and ruthenium. In this case, the agglomeration and corrosion of nanostructures were accelerated, leading to a decline in the balance of catalytic performance.

In light of these findings, the research team has proposed several avenues for further catalyst research. They emphasize the need for a metric that can simultaneously evaluate both activity and stability, introducing the concept of the activity-stability factor, initially introduced by Kim's research group in 2017.

Additionally, they advocate for retaining superior catalyst properties even after the formation of nanostructures to enhance the electrochemical active surface area. Careful selection of candidate materials that can synergize effectively when alloyed with other metals is also highlighted. While this study may not present specific outcomes like the development of new catalysts, it offers crucial insights and considerations for future catalyst design.

Professor Yong-Tae Kim, the driving force behind the research, emphasized that this work marks the beginning, not the conclusion, of their journey. He expressed his dedication to the continuous development of efficient water electrolysis catalysts based on the insights gained from this study, reinforcing the commitment to advancing sustainable hydrogen production.

Source: ACS Catalysis

Kyu-Su Kim et al, Deteriorated Balance between Activity and Stability via Ru Incorporation into Ir-Based Oxygen Evolution Nanostructures, ACS Catalysis (2023). DOI: 10.1021/acscatal.3c01497