A research team of Russian scientists from Skoltech, the G. K. Boreskov Institute of Catalysis of the Siberian Branch of the Russian Academy of Sciences, and Tomsk Polytechnic University has developed a novel catalyst for carbon dioxide (CO₂) photocatalysis. Studies have demonstrated that the composite catalyst, based on titanium dioxide and a high-entropy carbide produced at Tomsk Polytechnic University using a vacuum-free electric arc synthesis method, boosts methane yield sevenfold compared to conventionally used titanium oxide. The new photocatalyst holds promise for future applications in CO₂ utilization and clean fuel production. The results have been published in the journal Materials Today Energy.
Developing efficient technologies for carbon dioxide utilization and its conversion into valuable products is one of the most critical challenges facing the global scientific community. Photocatalysis stands out as a highly promising avenue, enabling reactions under ambient conditions. Traditional photocatalysts rely on titanium dioxide combined with expensive noble metals like gold, platinum, or palladium. Meanwhile, several other material classes — such as borides, carbides, transition metals, and, more recently, high-entropy materials based on them — are showing potential for catalytic applications.
In this study, high-entropy carbides demonstrated remarkable potential for catalysis and CO₂ processing via photocatalytic reactions. This is a new class of materials composed of four to five (or more) different metals combined with carbon. Their key feature is their ability to withstand high temperatures and energy flux densities. By combining different elements in their composition, it is possible to achieve the desired balance of properties, such as catalytic activity and selectivity, melting point, oxidation temperature, specific weight, and others.
“In our research, we created and studied composite photocatalysts made of titanium dioxide and a high-entropy carbide synthesized from powders of titanium, zirconium, niobium, hafnium, tantalum, and carbon using a vacuum-free electric arc method. The properties of high-entropy carbides are still poorly understood, and in this work, our colleagues have discovered a potential application for them in the field of photocatalysis,” says one of the paper’s authors, Alexander Pak, head of the Laboratory for Advanced Energy Materials at the School of Energy & Power Engineering.
The vacuum-free electric arc synthesis method is an original approach to material production being developed by scientists at Tomsk Polytechnic University. It allows materials to be synthesized using a direct current arc discharge in open air, without the need for special vacuum or gas equipment. Previously, researchers from Tomsk were the first to successfully produce a high-entropy carbide in atmospheric plasma.
The explanation for why the high-entropy carbide works within the composite photocatalyst was obtained through a study of its electronic and adsorption properties using digital modeling techniques. Modeling of gas adsorption (precursors and reaction products) on the high-entropy carbide revealed that metal atoms within the carbide structure lose their electronic identity. This leads to a greater number of active adsorption sites on the surface of the high-entropy carbide particles.
“We conducted extensive computations to understand how the local structure of the high-entropy carbide’s active center influences its adsorptive and catalytic properties before beginning experimental research. The dataset we obtained allowed us to draw conclusions about the promising application of this material in photocatalytic reactions and will also be used by us to develop new predictive models based on machine learning,” explained the study’s leader, Alexander Kvashnin, a professor at the Skoltech Materials Center.
