Very Low Temperature CO Oxidation over Atomically Precise Au₂₅ Nanoclusters on MnO₂

Area of Science:

• Heterogeneous catalysis
• Nanomaterials science
• Surface chemistry

Background:

• Atomically precise gold nanoclusters (Au25) are of interest in catalysis.
• Au25 nanoclusters have shown limited performance in low-temperature CO oxidation compared to other gold catalysts.
• Manganese oxide (MnO2) is a potential support material for gold catalysts.

Purpose of the Study:

• To develop a highly active and stable gold nanocatalyst for low-temperature CO oxidation.
• To investigate the effect of supporting Au25 nanoclusters on MnO2.
• To optimize catalyst performance through pretreatment temperature adjustments.

Main Methods:

• Deposition of Au25(SR)18 nanoclusters onto a MnO2 support.
• Optimization of catalyst pretreatment temperature.
• Characterization using X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), and X-ray diffraction (XRD).
• In-situ modulation excitation spectroscopy (MES) for active site identification.

Main Results:

• The Au25/MnO2 catalyst demonstrated significantly enhanced activity and stability.
• 100% CO conversion was achieved at -50°C, with 50% conversion below -70°C.
• Au25 nanoclusters remained stable on the MnO2 support even after high-temperature pretreatment.
• MES confirmed Au clusters as the active sites for CO oxidation.

Conclusions:

• Optimized Au25/MnO2 is a highly effective catalyst for low-temperature CO oxidation.
• Atomically precise Au25 nanoclusters can serve as primary active sites for catalysis at very low temperatures.
• The stability and activity of the catalyst highlight its potential for practical applications.