Enabling Specific Photocatalytic Methane Oxidation by Controlling Free Radical Type

Area of Science:

• Catalysis
• Photochemistry
• Sustainable Chemistry

Background:

• Selective oxidation of methane (CH4) to oxygenates (CH3OH, HCHO) is crucial for sustainable chemical synthesis.
• Controlling reaction selectivity and preventing overoxidation remain significant challenges in CH4 oxidation.

Purpose of the Study:

• To develop a highly efficient photocatalyst for selective CH4 oxidation to CH3OH and HCHO.
• To achieve high selectivity and productivity by precisely controlling radical formation.

Main Methods:

• Rational design of Au/In2O3 photocatalysts with tunable band structures and active site sizes (single atoms vs. nanoparticles).
• Investigating the role of as-formed radicals (•OOH and •OH) in directing reaction pathways.
• Evaluating catalyst performance under mild conditions for CH4 photooxidation.

Main Results:

• Au single atoms on In2O3 (Au1/In2O3) achieved 97.62% HCHO selectivity and 6.09 mmol g-1 yield.
• Au nanoparticles on In2O3 (AuNPs/In2O3) achieved 89.42% CH3OH selectivity and 5.95 mmol g-1 yield.
• Demonstrated simultaneous high selectivity and productivity for both products.

Conclusions:

• Precise control over radical formation via photocatalyst design is key to selective CH4 oxidation.
• The developed Au/In2O3 catalysts offer a novel pathway for efficient and selective production of methanol and formaldehyde from methane.
• This strategy opens new avenues for utilizing methane as a sustainable chemical feedstock.