Hse scientists discover method to convert CO₂ into fuel without expensive reagents

Researchers at HSE MIEM, in collaboration with Chinese scientists, have developed a catalyst that efficiently converts CO₂ into formic acid. Thanks to carbon coating, it remains stable in acidic environments and functions with minimal potassium, contrary to previous beliefs that high concentrations were necessary. This could lower the cost of CO₂ processing and simplify its industrial application—e.g. in producing fuel for environmentally friendly transportation. The study has been published in Nature Communications. 

The electrochemical reduction of carbon dioxide is a process in which CO₂ is converted into other chemical compounds through the application of an electric current. It has long been regarded not only as a method for recycling CO₂, but also as a source of valuable raw materials such as formic acid, which can serve as a liquid fuel, solvent, or chemical industry feedstock. 

However, a major challenge in the electrochemical reduction of CO₂ is the occurrence of a side reaction that produces hydrogen, thereby reducing the overall efficiency of the process. In alkaline solutions, this issue is typically addressed by adding more potassium ions (K⁺); however, this not only increases the cost of the process but also leads to precipitation, which clogs the system and hinders its operation. Conversely, in an acidic environment, catalysts degrade rapidly and lose their effectiveness.

A team of researchers, including those from HSE University, has proposed an alternative approach. They developed a catalyst that remains stable in acidic environments while requiring only a minimal amount of potassium. The catalyst is made from indium oxide (In₂O₃) and coated with a thin layer of carbon.

First, through computer modelling, the researchers at HSE MIEM determined how to control the distribution of ions on the catalyst's surface. The model revealed that the carbon coating not only protects the catalyst from degradation but also creates an electric field that holds potassium ions on its surface. As a result, potassium does not precipitate, and undesirable side effects are minimised.

To test the model's predictions, Chinese scientists synthesised indium oxide nanoparticles and encapsulated them in a thin layer of carbon. The team then conducted a series of experiments in an electrolyte reactor, using a highly acidic environment and a fraction of the potassium typically used in conventional systems. The tests showed that even under these conditions, the catalyst remained stable, maintaining activity for over 100 hours, with a CO₂ to formic acid conversion efficiency of 98.9%.

Dongyu Liu

'We have demonstrated that it is possible to eliminate excess potassium hindering the system's operation. This approach not only reduces the cost of the process but also improves catalyst stability,' explains Dongyu Liu, Assistant Professor at HSE MIEM.

To verify that the carbon coating is the key factor, the researchers conducted additional tests. They found that without the coating, indium oxide rapidly reduces to metallic indium, which is far less effective at facilitating the electrochemical reduction of CO₂. This confirms that the carbon layer protects the catalyst, preventing its degradation.

This method not only simplifies CO₂ processing technology but also makes it more accessible for industrial applications. Unlike conventional alkaline systems, it does not require a high concentration of potassium and prevents precipitation. The implementation of this technology in real-world systems could make carbon dioxide recycling more environmentally sustainable.

Andrey Vasenko

'We have made the process more stable and scalable, bringing the electrochemical reduction of carbon dioxide closer to real-world industrial applications,' says Andrey Vasenko, Professor at HSE MIEM. 'This technology can be useful not only for synthesising formic acid but also for other processes related to carbon dioxide conversion.'