Scientists developed a photocatalyst that can convert carbon dioxide into methane with solar energy. Courtesy of Daegu Gyeongbuk Institute of Science and Technology

Scientists in Korea and the United States developed a material that harnesses solar energy to efficiently turn carbon dioxide (CO2) into hydrocarbons such as methane, a gas fuel for heating, cooking and powering vehicles.

With further developments, the optimized photocatalyst could be used in reactors installed on top of chimneys of power plants, factories or other major sources of CO2 to directly convert emissions into an energy resource, the lead researcher said.

In 2021, the Earth saw record-high levels of the three main greenhouse gases, namely carbon dioxide, methane and nitrous oxide, according to the World Meteorological Organization. The warming effect on the climate by long-lived greenhouse gases, especially CO2, surged by almost 50 percent between 1990 and 2021.

Scientists have been exploring ways to bring down CO2 concentration in the atmosphere. One potential method is to separate greenhouse gases from emissions and store them underground or under the sea.

In Su-Il, who heads the photo and electrochemical materials science and engineering lab at Daegu Gyeongbuk Institute of Science and Technology, said the capture and underground storage of CO2 might not be the ultimate solution because the gas could leak back into the atmosphere during incidents like earthquakes.

To seek alternative approaches, the professor has been studying the conversion of CO2 into useful hydrocarbons for more than a decade.

In a recent study, his team looked into photocatalysts ― a material that absorbs light to provide energy to a reacting substance. The resulting chemical reaction converts CO2 into methane in this case.

“We don't need to use electricity. We just need solar power, water and the highly efficient solar-driven catalyst,” he said.

To improve the efficiency of commercially available photocatalysts made of titanium dioxide, the team modified the material by incorporating ruthenium and silver nanoparticles as co-catalysts.

They found that the enhanced photocatalyst converts 135 times more methane compared to its original version, according to a study published in the peer-reviewed journal Carbon Energy in July in collaboration with researchers at the University of California?Riverside.

In said the technology could play a role in future CO2 reduction and recycling, a strategy to combat climate change along with lowering energy consumption and switching to renewable and nuclear energy sources.

Apart from using it at fossil-fuel-burning power plants, a major energy supply for Korea, the photocatalyst could also be used to process atmospheric CO2 gathered into tanks, he said, adding that this is also a potential application for Mars exploration.

“This application is not only on the Earth but also on Mars,” he said. The atmosphere on the Red Planet is mainly composed of CO2.

“To live on Mars, we have to utilize carbon dioxide as fuel.”

Holly Chik is a science reporter with the South China Morning Post. She is currently based in Seoul, reporting for both The Korea Times and the South China Morning Post under an exchange program.