Development of a Self-Powered Hydrogen Production System to Overcome Green Hydrogen Limitations

A self-powered hydrogen production system has been developed that overcomes the limitations of existing hydrogen production methods such as green hydrogen, enabling stable hydrogen production.

On the 22nd, KAIST announced that Professor Kang Jeong-gu's research team from the Department of Materials Science and Engineering developed a self-powered hydrogen production system based on a zinc-air battery.

An air battery is a type of primary battery that absorbs oxygen from the air and uses it as an oxidizing agent. Its long lifespan is an advantage, while its low electromotive force is considered a disadvantage.

Schematic diagram of a self-powered hydrogen production system based on a zinc-air battery using a composite functional catalyst material. Provided by KAIST

Hydrogen (H2) is a raw material for synthesizing high value-added substances. In particular, hydrogen's theoretical energy density is more than three times higher than that of conventional fossil fuels such as gasoline and diesel, with an energy density of 142 MJ/kg, drawing attention as a clean fuel.

The importance of the hydrogen economy system is increasing as a fundamental solution to bring about changes in the national economy, global competitiveness, and citizens' lives.

However, most current hydrogen production methods involve the problem of carbon dioxide (CO2) emissions.

For the same reason, clean green hydrogen produced by decomposing water (H2O) using electricity generated from renewable energy sources such as solar and wind power is proposed as a solution.

However, green hydrogen faces challenges in practical use due to irregular power generation depending on environmental factors such as temperature and weather, and the resulting low water-splitting efficiency.

To overcome these issues, air batteries capable of generating sufficient voltage (above 1.23 V) for water splitting and hydrogen production have attracted attention as power sources. However, they also have limitations, such as the need for precious metal catalysts to achieve sufficient capacity and the rapid degradation of catalyst performance during long-term charge-discharge cycles.

Developing catalysts effective for water splitting reactions (oxygen evolution, hydrogen evolution) and materials stable under repetitive charge-discharge reactions of zinc-air battery electrodes (oxygen reduction, oxygen evolution) has emerged as an essential task.

(Front row from left) Dongwon Kim, Ph.D. candidate; Junggu Kang, Professor; Jihoon Kim, Master's candidate. Provided by KAIST

In this regard, the research team proposed a synthesis method for a non-precious metal catalyst material (G-SHELL) that is effective in three different catalytic reactions (oxygen evolution, hydrogen evolution, oxygen reduction) using nanosized metal-organic frameworks grown on graphene oxide.

They also confirmed that when the developed catalyst material was used as the air electrode material in an air battery, it exhibited an energy density five times higher than conventional batteries (797 Wh/kg), high power characteristics (275.8 mW/cm²), and stable operation over long periods under repeated charge-discharge conditions.

Above all, zinc-air batteries operate with an aqueous electrolyte, making them safe from fire hazards and suitable for next-generation energy storage devices. Based on this, the research team expects that the environmentally friendly method of producing hydrogen by linking zinc-air batteries with water electrolysis systems can be practically applied in the field.

Professor Kang said, “The self-powered hydrogen production system based on zinc-air batteries will serve as a new breakthrough to overcome the limitations seen in current green hydrogen production.”

Meanwhile, this research was conducted with support from the Ministry of Science and ICT and the Nano and Materials Technology Development Project Future Technology Research Laboratory of the National Research Foundation of Korea.

The research results (paper), co-authored by PhD candidate Kim Dong-won and master's student Kim Ji-hoon from KAIST's Department of Materials Science and Engineering as joint first authors, were published on the 17th of last month in the international interdisciplinary journal Advanced Science.

This content was produced with the assistance of AI translation services.