(a) The figure shows the color change of the photocatalyst developed by the research team. It shows that the reduced titanium dioxide absorbs light more towards the right and the color gets darker. (b) A graph comparing the methane production efficiencies of the photocatalysts developed by the research team and the existing photocatalysts. The methane production efficiency of the photocatalyst (0.35-BT-30) developed by the team is superior to other photocatalysts. (c) The energy level diagram of the photocatalyst developed by the research team. It shows the characteristic that the oxygen atoms on the surface of titanium dioxide are defected and the band gap is controlled by changing oxidation number from 4 to 3.
A research team of Energy Science and Engineering at DGIST has succeeded in developing a titanium dioxide (TiO2)-based high efficiency photocatalyst that converts carbon dioxide to methane using a simple reduction method.
The photocatalysts developed by the research team can be used to convert carbon dioxide to fuels like methane. Therefore, it is expected to be applied to technologies for carbon dioxide abatement and resource reclamation.
As is now well known, anthropogenic emission of greenhouse gases, particularly CO2, is a significant factor driving global climate change; sustainable, low carbon, readily portable fuels are one of the most pressing needs of modern society. To that end, there has been a worldwide effort underway to find ways to convert carbon dioxide, a major contributor to global warming, into a usable fuel, such as hydrogen, methane, ethanol, methanol, and butanol.
In order to utilize carbon dioxide as a resource, it is essential to increase the conversion efficiency and light absorption efficiency when converting carbon dioxide into fuel, and to make photocatalyst help to prevent secondary harmful substances.
High-efficiency photocatalyst development technology that synthesizes materials such as titanium dioxide, copper oxide, and reduced graphene oxide, or controls the structure and surface of photocatalyst material is regarded as the core of carbon dioxide recycling technology.
Surprisingly, DGIST’s research team has discovered a synthesis method which rapidly reduces titanium dioxide (TiO2) at low temperatures using a strong reducing agent, sodium borohydride (NaBH4).
In the study, titanium dioxide-based photocatalysts using this synthesis method showed 12.49% conversion of methane to photochemical carbon dioxide on the gas phase, which represents the highest conversion rate among the introduced photocatalysts so far.
In addition, the photocatalyst developed by the research team has the controlled band gap through the conversion of the oxidation number from 4 to 3 by breaking the oxygen atoms on the surface of titanium dioxide. This change increases the amount of light absorption and efficiently separates the charge, resulting in higher carbon conversion of carbon dioxide. Moreover, the experiment has also proved that the efficiency of methane conversion of carbon dioxide can be increased up to 29 times using platinum nanoparticles.
Professor In stated, “The newly developed titanium dioxide photocatalyst is superior to the other photocatalysts reported so far as it has outstanding carbon dioxide conversion efficiency as well as excellent stability.” He also mentioned, “We would like to contribute to the development of carbon dioxide reduction and recycling technology by conducting further researches to improve conversion efficiency to the extent that it can be commercialized.”
