Bimetallic Catalysis for Carbon Monoxide Oxidation

Bimetallic catalysts integrate two distinct metal elements within a single active phase, yielding synergistic interactions that enhance the adsorption, activation and conversion of carbon monoxide. By tuning the composition, structure and oxidation state of the alloy sites—often supported on oxides such as ceria or titania—it is possible to lower activation barriers, modify reaction pathways and improve resistance to sintering or poisoning. Central to their performance is the dynamic interplay between lattice oxygen (or surface oxygen species) and metal ensembles, which can follow associative or dissociative mechanisms for CO oxidation. These materials find application in emission control, hydrogen purification for fuel cells and indoor air filtration, owing to their ability to achieve complete CO conversion at low temperatures and under variable gas compositions. Advances in nanostructuring and in situ characterisation have revealed the crucial roles of oxygen vacancies, intermetallic bonds and support–metal interactions in governing catalytic rates and stability.

Research from Nature Portfolio

Recent studies have demonstrated that a semiconductor–metal hybrid catalyst comprising copper oxide and silver exhibits markedly improved CO oxidation activity through surface polarisation charges. First-principles calculations indicate that the Schottky barrier at the CuO/Ag interface injects charge into oxygen vacancies, facilitating rapid oxygen recovery via a Mars–van Krevelen process. This synergistic mechanism not only lowers the apparent activation energy but also enhances the resilience of the catalyst under cyclic redox conditions, pointing to a new strategy for designing heterogeneous bimetallic systems with sustained low-temperature performance.

Bimetallic Catalysis for Carbon Monoxide Oxidation publication trend

The graph below shows the total number of articles in bimetallic catalysis for carbon monoxide oxidation across all publications each year (not limited to Nature Index journals).

Technical terms

Bimetallic catalyst: A catalyst composed of two different metals whose interaction produces unique active sites and enhanced performance.

Support: A solid material, typically an oxide, that disperses and stabilises metal nanoparticles and influences catalytic behaviour.

Oxygen vacancy: A defect site in an oxide lattice where an oxygen atom is absent, facilitating oxygen activation and mobility.

Associative reaction mechanism: A pathway where molecular oxygen remains intact as it reacts with adsorbed CO to form CO2.

Dissociative reaction mechanism: A pathway where molecular oxygen splits into atomic oxygen before reacting with CO on the catalyst surface.

Preferential Oxidation (CO-PROX): A selective process in which CO is oxidised in the presence of excess hydrogen, crucial for fuel-cell feed purification.

Mars–van Krevelen mechanism: A redox mechanism in which lattice oxygen from the catalyst directly oxidises reactants and is subsequently replenished by gas-phase oxygen.

References

1. Effect of Reaction Atmosphere on Catalytic CO Oxidation Over Cu-Based Bimetallic Nanoclusters on a CeO2 Support. Physical Review Applied (2023).
2. Ru–Pd Bimetallic Catalysts Supported on CeO2-MnOX Oxides as Efficient Systems for H2 Purification through CO Preferential Oxidation. Catalysts (2018).
3. Carbon Monoxide Oxidation Promoted by Surface Polarization Charges in a CuO/Ag Hybrid Catalyst. Scientific Reports (2020).
4. High-Performing Au-Ag Bimetallic Catalysts Supported on Macro-Mesoporous CeO2 for Preferential Oxidation of CO in H2-Rich Gases. Catalysts (2020).