Carbon monoxide is invisible, odorless and potentially lethal, yet removing it from exhaust streams is far more complicated than simply exposing it to a catalyst. The reaction that converts CO into carbon dioxide must remain fast under realistic conditions, where water vapor and sulfur dioxide can occupy active sites, block oxygen movement and gradually weaken performance. A study published in Nature Communications reports a strategy designed to confront all three problems at once: placing titanium atoms individually across a manganese oxide–iron oxide support and using them to reshape the electronic structure of oxygen at the catalyst surface.
The material, described as atomically dispersed Ti on MnOx-Fe2O3, brings together three chemically distinct components. Manganese oxides are known for their ability to cycle between oxidation states, a property that can help supply reactive oxygen during CO oxidation. Iron oxide can contribute structural stability and additional redox activity. Titanium, meanwhile, is introduced not as conventional nanoparticles or large crystalline particles, but as isolated atoms dispersed across the mixed oxide surface. At this scale, every titanium atom can interact directly with neighboring manganese, iron and oxygen atoms, creating a highly defined catalytic environment.
The central finding is that these individual titanium atoms do more than provide additional reaction sites. They alter the behavior of oxygen’s 2p orbitals, the electronic states that strongly influence how oxygen atoms bond, move and participate in surface reactions. In a solid catalyst, the energy and distribution of these orbitals help determine whether oxygen can be activated and transferred to an adsorbed molecule. By tailoring the local electronic structure, the dispersed titanium is presented as an atomic-level regulator of the oxygen chemistry needed to convert carbon monoxide efficiently.
CO oxidation generally proceeds when carbon monoxide binds to a catalyst surface and reacts with oxygen supplied by the catalyst or by the surrounding gas. The carbon and oxygen atoms combine to form carbon dioxide, while the catalyst must restore its oxygen supply so the cycle can continue. This requires a carefully balanced surface: oxygen must be reactive enough to participate in the reaction, but not so weakly bound that the catalyst becomes unstable. The MnOx-Fe2O3 support provides a redox-active framework, while isolated titanium centers adjust the electronic conditions around oxygen and help tune this balance.
That electronic tuning may be especially important because catalytic activity is not determined only by the number of exposed atoms. The arrangement of atoms and the energy of their electronic states can control how strongly reactants attach, how easily bonds break and form, and how rapidly oxygen migrates through the surface. The study’s focus on O 2p orbitals therefore points to a deeper design principle: improving a catalyst may depend less on adding more material and more on precisely modifying the orbitals that govern its most important chemical steps.
Industrial exhaust, combustion systems and other gas-treatment environments rarely contain only carbon monoxide and oxygen. Water vapor is common, and sulfur dioxide can be particularly damaging because sulfur-containing species may bind strongly to metal centers and form persistent surface compounds. This phenomenon, often called sulfur poisoning, can suppress the sites responsible for oxygen activation. Water can also compete with CO for adsorption sites or change the surface structure through hydroxyl formation. A catalyst that performs well only in dry, sulfur-free laboratory gas may therefore lose much of its practical value.
The reported titanium-modified catalyst is designed to resist these realistic disturbances. Its resistance to H2O and SO2 is linked to the way atomically dispersed Ti reshapes the surface electronic environment and stabilizes the functional oxygen network. Rather than allowing water or sulfur dioxide to completely disrupt the redox cycle, the modified surface is intended to preserve access to active oxygen and maintain the chemical pathways required for CO oxidation. This combination of activity and durability is crucial for technologies expected to operate continuously, where frequent regeneration or replacement would be costly.
The work also highlights why atomic dispersion has become a major direction in heterogeneous catalysis. When a metal is assembled into nanoparticles, many atoms remain buried inside the particle and contribute little to the surface reaction. Isolated atoms, by contrast, can maximize the use of the added element, provided they remain stable and do not migrate or cluster during operation. Their surrounding support becomes part of the active site, making the catalyst a cooperative system rather than a simple mixture of separate ingredients. In the MnOx-Fe2O3 material, titanium’s performance depends on its interaction with the oxide lattice and the oxygen orbitals around it.
The implications extend beyond one formulation or one pollutant. The study suggests that catalysts for emissions control could be engineered by deliberately tuning orbital structures, rather than relying solely on surface area, particle size or the overall chemical composition. Such an approach could help address the difficult trade-off between high activity and resistance to poisons, a challenge shared by catalysts used for carbon monoxide, volatile organic compounds and other air pollutants. The findings may also encourage researchers to examine how isolated atoms modify oxygen chemistry in other mixed-metal oxide systems.
For now, the significance of the work lies in its atomic-scale explanation of a practical catalytic problem. By dispersing titanium one atom at a time on MnOx-Fe2O3, the researchers connect the electronic structure of oxygen with the ability of a catalyst to oxidize CO while tolerating water and sulfur dioxide. That link offers a blueprint for designing more resilient emission-control materials—catalysts that are not merely active under ideal conditions, but capable of continuing their work in the chemically crowded environments where cleaner air is most urgently needed.
Subject of Research: Atomically dispersed titanium catalysts for carbon monoxide oxidation and resistance to water and sulfur dioxide
Article Title: Atomically dispersed Ti on MnOx-Fe2O3 tailors O 2p orbitals for CO oxidation and H2O/SO2 resistance
Article References: Zhao, Y., Wang, P., Jiang, J. et al. “Atomically dispersed Ti on MnOx-Fe2O3 tailors O 2p orbitals for CO oxidation and H2O/SO2 resistance.” Nature Communications (2026). https://doi.org/10.1038/s41467-026-76406-6
Image Credits: AI Generated
DOI: 10.1038/s41467-026-76406-6
Keywords: carbon monoxide oxidation, atomically dispersed titanium, MnOx-Fe2O3, O 2p orbitals, heterogeneous catalysis, sulfur dioxide resistance, water resistance, emission control
