Microalgae-derived Co₃O₄ nanomaterials for catalytic CO oxidation.

Area of Science:

• Materials Science
• Environmental Chemistry
• Catalysis

Background:

• Efficient carbon monoxide (CO) oxidation is crucial for mitigating health and environmental pollution.
• Developing sustainable synthesis routes for effective catalysts is an ongoing research priority.

Purpose of the Study:

• To synthesize nanosized cobalt oxide (Co3O4) catalysts using microalgae extracts.
• To investigate the impact of microalgae-derived metabolites and calcination temperatures on Co3O4 catalyst properties and CO oxidation activity.

Main Methods:

• Synthesis of Co3O4 nanomaterials using extracts from *Spirulina platensis*, *Chlorella vulgaris*, and *Haematococcus pluvialis*.
• Characterization of synthesized Co3O4 catalysts, including morphology, structure, and surface composition.
• Evaluation of catalytic activity for CO oxidation under various conditions.
• In situ studies to probe reaction mechanisms, including oxygen mobility and carbonate formation.

Main Results:

• Successfully synthesized Co3O4 nanomaterials with diverse morphologies (octahedral, nanosheet, spherical) and structural defects.
• Observed surface segregation of phosphorous (P) and potassium (K) from microalgae extracts, significantly enhancing catalytic CO oxidation activity.
• Microalgae-derived catalysts demonstrated superior performance compared to a commercial benchmark, especially when normalized by specific surface area.
• In situ studies revealed distinct differences in oxygen mobility and carbonate intermediates during CO oxidation over the synthesized catalysts.

Conclusions:

• Microalgae extracts provide a sustainable pathway for producing highly active Co3O4 nanocatalysts.
• The presence of P and K impurities from the extracts plays a vital role in boosting catalytic CO oxidation efficiency.
• These findings offer valuable insights for designing next-generation, high-performance Co3O4 nanocatalysts through eco-friendly synthesis strategies.