Dr. Ji-Hyung Han's research team from the Convergence Research Center of Sector Coupling & Integration at the Korea Institute of Energy Research (President Yi, Chang-Keun, hereinafter "KIER") has developed a high-performance carbon cloth-based electrode that maintains stable performance even under high current conditions. The newly developed electrode is the first seawater electrolysis electrode using a carbon cloth support that has demonstrated successful continuous operation for over 800 hours under high current conditions, highlighting its potential for commercialization.
Water electrolysis is an eco-friendly technology that produces hydrogen by splitting water. Although it primarily relies on freshwater, growing concerns over global water scarcity have drawn increasing attention to seawater electrolysis, which uses seawater directly.
The performance and lifespan of seawater electrolysis systems depend heavily on the catalyst used in the electrode and the electrode support that evenly distributes the catalyst. While precious metal-based catalysts such as platinum and ruthenium are commonly used, recent research has focused on non-precious metal catalysts or approaches that minimize the use of precious metals due to cost concerns.
There are also issues with the electrode support. Metal-based supports are highly vulnerable to corrosion caused by chloride ions, clearly limiting their lifespan. As an alternative, carbon cloth has emerged due to its excellent electrical conductivity, corrosion resistance, flexibility, and cost-effectiveness. However, existing carbon cloth-based catalysts have faced challenges in commercialization, as they suffer from performance degradation and structural damage during high-current operation (above 500 mA/cm²) and long-term use over 100 hours, which are required for industrial applications.
The research team overcame the limitations of conventional electrodes by developing a carbon cloth-based electrode with enhanced hydrogen production efficiency through an optimized acid treatment process. The newly developed electrode reduced the overpotential applied to the electrode by 25%, enabling a 1.3 times more efficient hydrogen evolution reaction (HER) compared to existing electrodes.
To enhance the reactivity of the electrode, the research team focused on acid-treating the carbon cloth. The acid treatment involves immersing the cloth in a highly concentrated nitric acid solution at 100°C for one hour. However, evaporation during the process caused fluctuations in acid concentration, which posed a challenge. To address this, the team designed a specialized acid treatment vessel that prevents concentration changes, successfully optimizing the surface treatment of the carbon cloth support.
The acid-treated carbon cloth support exhibits high hydrophilicity, which promotes the uniform distribution of cobalt, molybdenum, and ruthenium ions across its surface. In particular, the precious metal ruthenium is evenly dispersed throughout the support, enabling excellent electrochemical performance even with a minimal amount.
As a result, the ruthenium-incorporated cobalt-molybdenum (CoMo) catalyst achieved a roughly 25% reduction in overpotential compared to conventional CoMo catalysts, despite using only about 1% ruthenium by weight. By lowering the required overpotential, the catalyst enabled a hydrogen evolution reaction that is approximately 1.3 times more efficient at the same current density.
The catalyst-coated electrode maintained its initial performance even after over 800 hours of continuous operation under high current conditions of 500 mA/cm². Post-operation analysis of the electrode revealed no leaching of metal ions such as ruthenium and cobalt into the electrolyte, indicating excellent corrosion resistance and structural stability. Additionally, the team successfully synthesized a large-area electrode measuring 25 cm², showing potential for scalability and practical application.
Dr. Ji-Hyung Han of KIER stated, "This technology marks the world's first successful case of long-term operation over one month under industrial-level high current conditions in seawater electrolysis using a carbon cloth-based electrode." She added, "We plan to further advance the technology to the demonstration level through extended durability testing beyond 1,000 hours and research on scaling up to large-area cell modules and stacks."
This research was supported by the National Research Council of Science & Technology (NST) under the Ministry of Science and ICT. The results were published in the May 2025 online edition of the prestigious international journal Applied Surface Science (Elsevier).
