Researchers at KAIST have created an innovative hydrogen production system that addresses the existing challenges in green hydrogen generation. Utilizing a water-splitting mechanism with an aqueous electrolyte, this system aims to minimize fire hazards and ensure consistent hydrogen production.
On October 22nd, KAIST, led by President Kwang Hyung Lee, announced that a team under the direction of Professor Jeung Ku Kang from the Department of Materials Science and Engineering has introduced a self-sustained hydrogen production system that leverages a high-efficiency zinc-air battery*.
*Zinc-air battery: A type of primary battery that draws oxygen from the atmosphere to serve as an oxidant. While it boasts a long lifespan, its lower electromotive force is a drawback.
Hydrogen (H2) is a crucial component for producing high-value materials and is emerging as a clean energy source, boasting an energy density (142 MJ/kg) that is over three times greater than that of conventional fossil fuels (like gasoline and diesel). However, traditional hydrogen production techniques often impose environmental strain due to carbon dioxide (CO2) emissions.
While green hydrogen can be generated through water splitting with renewable energy sources like solar and wind, the inconsistent nature of these energy sources—affected by weather and temperature variations—results in low efficiency in water splitting.
To address this challenge, air batteries capable of producing sufficient voltage (over 1.23V) for water splitting have drawn interest. However, achieving the necessary capacity typically requires costly precious metal catalysts, and the efficiency of these catalysts diminishes significantly during prolonged charging and discharging processes. Therefore, it is vital to create catalysts that effectively promote water-splitting reactions (oxygen and hydrogen generation) and to find materials that can sustain repeated charge and discharge cycles (oxygen reduction and generation) in the electrodes of zinc-air batteries.
To tackle this issue, Professor Kang’s research team devised a method to synthesize a non-precious metal catalyst material (G-SHELL) that is effective for three different catalytic processes (oxygen evolution, hydrogen evolution, and oxygen reduction) by cultivating nano-sized metal-organic frameworks on graphene oxide.
The team integrated this newly developed catalyst into the air cathode of a zinc-air battery, demonstrating that it achieved around five times the energy density (797Wh/kg), impressive power capabilities (275.8mW/cm²), and maintained long-term stability even through repeated charging and discharging compared to traditional batteries.
Moreover, the zinc-air battery, which functions with an aqueous electrolyte, is shielded from fire hazards. This system is anticipated to serve as a next-generation energy storage solution linked with water electrolysis systems, providing an eco-friendly approach for hydrogen production.
Professor Kang remarked, “By creating a catalyst material that exhibits high activity and resilience for three different electrochemical catalytic reactions at low temperatures through straightforward methods, we have achieved a self-powered hydrogen production system using zinc-air batteries that represents a significant step forward in overcoming the limitations faced in green hydrogen production.”
PhD candidate Dong Won Kim and Jihoon Kim, a master’s student from the Department of Materials Science and Engineering at KAIST, served as co-first authors for this research, which was published in the international journal Advanced Science on September 17th, within the multidisciplinary materials science arena.
This study received support from the Nano and Material Technology Development Program of the Ministry of Science and ICT and the Future Technology Research Laboratory of the National Research Foundation of Korea.
