Aluminum: A new hero of hydrogen production

@ POSTECH

Aluminum (Al) has been considered as a material susceptible to corrosion, but it will become key to core technology in producing clean hydrogen energy. Recently, a POSTECH research team succeeded in dramatically improving the performance of hydrogen production catalysts using this unstable metal.

This research was conducted by the team of: Professor Yong-Tae Kim of the Department of Materials Science and Engineering, and Graduate Institute of Ferrous & Eco Materials Technology at POSTECH; Dr. Sang-Moon Jung of the Department of Materials Science and Engineering, Ph.D. candidate Byeong-Jo Lee, and professor Seoin Back's team of Sogang University. The research was recognized for its excellence and was published as the cover paper of "ACS Catalysis," an academic journal published by the American Chemical Society (ACS). Hydrogen is being spotlighted as a clean energy source replacing fossil fuels, and water electrolysis all of which is used to mass produce hydrogen using water. In particular, researches on alkaline water electrolysis using alkaline solution as an electrolyte are being actively conducted, as it is cost-effective and suitable for mass production.

Water electrolysis requires a catalyst that accelerates 2 important reactions. One of them is "hydrogen evolution reaction" (HER), which produces hydrogen gas (H2) by combining hydrogen ions (H+) and electrons. Another one is "oxygen evolution reaction" (OER), which produces oxygen gas (O2) as hydroxyl ions (OH-) lose electrons. However, nickel-iron (Ni-Fe) is a based catalyst mainly used in oxygen production reaction; it has had difficulties in commercializing due to its lack of activity and durability.

The research team solved the problem using aluminum. Aluminum is generally known to be easily corroded in alkaline environments, but the research team overcame the problem by designing it to form a stable structure on the surface of an electrode. As a result, aluminum efficiently controlled the existing catalytic electron structure without corrosion, accelerating oxygen production reaction.

Experiments conducted in an alkaline water electrolysis cell showed the results that the nickel-iron-aluminum (Ni-Fe-Al) catalyst improved performance by approximately 50% compared to existing catalysts. The research team confirmed that the aluminum catalyst maintained high current density even at low voltage. Additionally it was proven to be applicable in a large-scale hydrogen production process, as it maintained excellent stability in a long-term operation. Professor Yong-Tae Kim, the leader of this research, said, "This research broke the stereotypes of existing catalyst designs. By using this innovative approach of utilizing aluminum, we were able to drastically improve the performance of catalysts used in a hydrogen production system. I expect this research would substantially advance the age of hydrogen economy and become a new milestone of eco-friendly energy technology." Reference Highly Active and Stable Al-Doped NiFe Self-Supported Oxygen Evolution Reaction Electrode for Alkaline Water Electrolysis

Byung-Jo Lee, Sang-Mun Jung, Gwonho Yu, Hyun-Yup Kim, Jaesub Kwon, Kyu-Su Kim, Jaeik Kwak, Wooseok Lee, Dong Hyeon Mok, Seoin Back, Yong-Tae Kim https://pubs.acs.org/doi/10.1021/acscatal.4c04393 POSTECH