Catalytic Oxidation Mechanisms in Cobalt Oxide Systems

Cobalt oxide materials, most notably Co₃O₄ and CoO, have emerged as cost-effective catalysts for the oxidation of carbon monoxide and volatile organic compounds. The catalytic activity is underpinned by the facile interconversion of Co²⁺ and Co³⁺ sites, creating a dynamic redox couple that drives oxygen transfer to adsorbed reactants. Lattice oxygen species, mobilised through oxygen vacancies, participate directly in the Mars-van-Krevelen mechanism, while adsorbed CO and O₂ molecules can also react via a Langmuir–Hinshelwood pathway when surface vacancies are scarce. Morphology and particle size exert a strong influence on activity by modulating surface area, defect density and the ease of phase transformation between CoO and Co₃O₄. Operando spectroscopic studies have revealed that active sites are often minority species, with only a few surface cobalt ions undergoing redox cycles under reaction conditions. Stability under cyclic redox environments is enhanced by controlling grain boundaries and by combining cobalt oxides with supports such as TiO₂ or CeO₂. Advanced synthetic approaches, including bio-templated and hybrid nanostructures, have improved oxygen mobility and surface defect chemistry. Applications span vehicle exhaust abatement, indoor air purification and industrial gas treatment, where high conversion rates at low temperatures are critical to global emission-control strategies.

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Catalytic Oxidation Mechanisms in Cobalt Oxide Systems publication trend

The graph below shows the total number of articles in catalytic oxidation mechanisms in cobalt oxide systems across all publications each year (not limited to Nature Index journals).

Technical terms

Mars-van-Krevelen mechanism: Reaction pathway in which lattice oxygen in the catalyst oxidises reactants and is replenished by gas-phase oxygen.

Langmuir–Hinshelwood mechanism: Reaction route involving adsorption of both reactants on the catalyst surface prior to reaction.

Operando spectroscopy: In situ analytical technique that monitors catalyst structure and composition under actual working conditions.

Oxygen vacancy: Defect site in the oxide lattice where an oxygen atom is missing, often serving as an active site for adsorption and reaction.

Redox couple: Paired oxidation states of an element that interconvert during redox processes, crucial for catalytic cycles.

References

1. Operando Insights into CO Oxidation on Cobalt Oxide Catalysts by NAP-XPS, FTIR, and XRD. ACS Catalysis (2018).
2. Operando XAS and NAP-XPS investigation of CO oxidation on meso- and nanoscale CoO catalysts. Catalysis Today (2019).
3. Co3O4−CeO2 Nanocomposites for Low‐Temperature CO Oxidation. Chemistry - A European Journal (2021).
4. Synthesis-Structure-Activity Relationships in Co3O4 Catalyzed CO Oxidation. Frontiers in Chemistry (2018).
5. Microalgae-derived Co 3 O 4 nanomaterials for catalytic CO oxidation. RSC Advances (2024).
6. Flexible Co3O4/TiO2 monolithic catalysts for low‐temperature and long‐term stable CO oxidation. Nano Select (2020).