A group of Korean researchers from the Pohang University of Science and Technology and Seoul National University has developed a new catalyst based on iron oxide, which has doubled the efficiency of producing green hydrogen without emitting carbon dioxide. The results of the study, which was supported by the Circle Foundation’s Science and Technology Innovation Program, the National Research Foundation of Korea and the Korea Institute of Materials Science, have been published in the journal Acta Materialia.
One of the most promising methods for producing hydrogen is the thermochemical decomposition of water, a process in which water molecules break down into hydrogen and oxygen under the influence of heat. An important role in this process is played by metal oxides, which can absorb and release oxygen repeatedly, serving as oxygen sponges.
However, most known oxides require extremely high temperatures (1,200–1,400 °C) to achieve that, which makes the process expensive and hard to use on an industrial scale. In order to solve this problem, the Korean scientists have created a new material: iron-poor nickel ferrite (Fe-poor NiFe₂O). Unlike conventional oxides, which can only absorb a limited amount of oxygen, this material changes its internal structure when heated, allowing it to absorb and release more oxygen even at temperatures below 1,000 °C.
Experiments showed that the new catalyst produces 0.528% hydrogen per gram of oxide, whereas the previous best result stood at 0.25%. Using a combination of experimental methods and computational modeling, the scientists also managed to accurately determine for the first time the areas in the iron oxide structure that play a key role in hydrogen formation. They found that the amount of hydrogen released depends directly on the transitions of iron atoms between oxidation states (Fe²⁺ and Fe³⁺).
According to study leader Hyungyu Jin, professor of mechanical engineering at the Pohang University of Science and Technology, these results pave the way for cheaper and more environmentally-friendly hydrogen production. The new approach also makes it possible to use solar heat or excess heat from industrial processes as an energy source.
