Turning waste alkaline water directly into clean hydrogen!

Dr. Sung Mook Choi and his research team at the Energy & Environmental Materials Research Division of the Korea Institute of Materials Science (KIMS) have successfully developed a highly durable non-precious metal-based hydrogen evolution catalyst for use in a direct electrolysis system employing waste alkaline water and anion exchange membranes (AEM). This breakthrough enables the production of clean hydrogen by directly utilizing alkaline wastewater generated from industrial processes. Notably, the developed catalyst was applied to a commercial-scale 64 cm² single-cell electrolysis system and demonstrated high hydrogen production efficiency with less than 5% performance degradation even after more than 2,000 hours of continuous operation—showing strong promise for real-world application.

Waste alkaline water is generated in large volumes from semiconductor manufacturing and metal etching/cleaning processes. However, due to the high cost of treatment and the potential environmental hazards, its reuse has remained economically inefficient. Anion exchange membrane water electrolysis (AEMWE) is considered a suitable method for directly utilizing waste alkaline water without the need for separate purification. Nonetheless, impurities and ions contained in the waste water have long interfered with the electrochemical reactions during electrolysis, significantly reducing hydrogen production efficiency.

 The research team discovered that the interface between nickel and cerium oxide exhibits weak binding energy with impurity ions present in waste alkaline water. This finding was theoretically validated through a collaborative study with Professor Min Ho Seo's group at Pukyong National University using density functional theory (DFT) calculations. Additionally, in collaboration with Professor Jang Yong Lee’s team at Konkuk University, the researchers developed a highly durable anion exchange membrane capable of maintaining performance even in impurity-rich environments.

Through this development process, the research team created a heterostructured non-precious metal catalyst based on nickel and cerium oxide. This catalyst can be directly applied to water electrolysis systems using waste alkaline water, without the need for complex purification processes. As a result, the team has established a technological breakthrough that not only reduces hydrogen production costs but also mitigates environmental pollution.

Conventional freshwater-based electrolysis systems require approximately 18 tons of raw water to produce 1 ton of hydrogen, from which about 9 tons of ultrapure water must be extracted. The cost of purifying this amount of water is estimated to be around USD 2,340. In contrast, the "direct waste alkaline water electrolysis technology" developed by the research team enables the use of large volumes of waste alkaline water without purification, dramatically reducing the cost of hydrogen production.

The research team synthesized the heterostructured, non-precious metal catalyst—based on nickel and cerium oxides—using a co-precipitation method, which allows for easy large-scale production by dissolving multiple substances and precipitating them simultaneously. The final catalyst was obtained through a two-step thermal treatment process. This approach enabled the formation of numerous oxygen vacancies and maximized electron–metal–support interactions (EMSI), thereby enhancing both catalytic performance and durability. The oxygen vacancies facilitate smoother electron flow, accelerating the hydrogen evolution reaction (HER), while the strong interactions between the metal and surrounding materials improve the catalyst’s operational stability and efficiency.

Once commercialized, this technology is expected to accelerate the self-sufficiency of key component materials in future mobility and power industries, while contributing to the creation of new markets for clean hydrogen. Building on this achievement, the research team is also working toward developing next-generation AEMWE technology that directly utilizes seawater as a source.

Dr. Sung Mook Choi, the lead researcher at KIMS, stated, “Through this study, we have demonstrated that industrial waste alkaline water can be effectively recycled for hydrogen production, significantly reducing production costs while also minimizing the risk of leakage accidents during wastewater transport.” He added, “Non-freshwater-based electrolysis technology is expected to garner increasing attention in the field of clean hydrogen production in the future.”

This research was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (No. RS-2024-00467234, National Hydrogen Hub Laboratory), the Nano & Material Technology Development Program through the National Research Foundation of Korea(NRF) funded by Ministry of Science and ICT(RS-2024-00409675), both funded by the National Research Foundation of Korea, as well as the Basic Research Program of the Korea Institute of Materials Science (KIMS). The research findings were published on June 9 in the prestigious international journal Advanced Science (Impact Factor: 14.3).

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About Korea Institute of Materials Science(KIMS)

KIMS is a non-profit government-funded research institute under the Ministry of Science and ICT of the Republic of Korea. As the only institute specializing in comprehensive materials technologies in Korea, KIMS has contributed to Korean industry by carrying out a wide range of activities related to materials science including R&D, inspection, testing&evaluation, and technology support.