Professor Jeungku Kang from the Department of Materials Science and Engineering announced on March 31 that his research team has developed a high-efficiency catalyst that produces hydrogen peroxide by using only sunlight, water, and oxygen. Hydrogen peroxide is a useful resource that is used in industries varying from dyeing and pharmaceuticals to even rocket propulsion fuels. 

Currently, production of hydrogen peroxide requires an anthraquinone process, which uses highly pressurized hydrogen gas and palladium catalyst. Not only is this process costly and potentially dangerous, it also releases organic pollutants. Alternatives to palladium catalysts are photocatalysts, which use semiconductor properties of transition metal oxides to produce hydrogen peroxide. They offer an economical and environmental advantage compared to the palladium catalysts currently prevalent in the industry. Photocatalysts use cobalt, titanium, and iron oxides, which are 1,500, 4,500, and 115,000 times cheaper than palladium, respectively. However, pre-existing photocatalysts require an additional oxidizing agent of alcohols to transfer electrons from oxygen in order to produce hydrogen peroxide. This agent, in fact, is more expensive than the hydrogen peroxide itself. Moreover, the resulting hydrogen peroxide rapidly decomposes on the catalyst surface, lowering the catalytic efficiency.

Professor Kang’s team was able to improve on the cost-efficiency of the method by adopting urea-hydrothermal synthesis to form nano-structures of cobalt, titanium, and iron oxides. Rather than conventionally mixing two or more types of metals to form one structure, the research team increased the ratio of cobalt precursors by exploiting the instability of iron oxides to separate iron and cobalt oxides. The resulting triphasic oxide photocatalyst has a unique structure: cobalt oxide in a two-dimensional nanosheet has a core-shell structured iron oxide-titanium oxide nanoparticle arranged on top. Through computational science, the research team succeeded in proving that nanoparticles in such core-shell structure efficiently absorb visible light and ultraviolet rays and transmit electrons.

Professor Kang highlighted that “This eco-friendly technology does not use hydrogen molecules and organic materials, so it is more economical because it uses relatively inexpensive transition metal oxides.” This research was supported by the Hybrid Interface Materials (HIM) Research Group of the Global Frontier Project of the Ministry of Science and ICT. Professor Kang’s research team published their findings online in the journal Advanced Energy Materials.