Buffered Hydroxyl Radical for Photocatalytic Non-Oxidative Methane Coupling

Area of Science:

• Photocatalysis
• Oxidation Chemistry
• Green Chemistry

Background:

• Hydroxyl radicals (⋅OH) are potent oxidants for methane activation but are difficult to control, leading to over-oxidation.
• Efficient and selective methane conversion remains a significant challenge in catalysis.

Purpose of the Study:

• To develop a strategy for controlling hydroxyl radical generation and consumption in photocatalysis.
• To achieve selective conversion of methane to C2+ hydrocarbons and hydrogen.

Main Methods:

• Utilized photo-irradiated Fe3+ in an aqueous solution with sulfate ions to buffer ⋅OH.
• Employed a Ru/SrTiO3:Rh photocatalyst for methane oxidation.
• Investigated the interaction between Fe3+ and SO42- to regulate ⋅OH dynamics.

Main Results:

• Achieved controlled ⋅OH participation in methane oxidation by buffering its concentration.
• Reported formation rates of 246 μmol h−1 for C2+ hydrocarbons and 418 μmol h−1 for H2.
• Obtained 10.2% methane conversion and 81% C2+ selectivity with 13.0% apparent quantum efficiency after 80 hours.

Conclusions:

• Demonstrated a novel strategy for controlling reactive radicals in photocatalysis.
• Showcased efficient and selective methane conversion using buffered ⋅OH.
• Opened new avenues for sustainable chemical synthesis via photocatalytic radical control.