fig5

Figure 5. (A) Reaction mechanism of photocatalytic methane conversion over Au–Pd/TiO₂; (B) EPR spectra of the catalyst suspension with DMPO as the spin probe; (C) Photocatalytic methane oxidation over TiO₂, Au/TiO₂, Pd/TiO₂, and Au–Pd/TiO₂ under UV-visible light irradiation (5 mg catalyst, 30 mL water, 3.0 MPa CH₄, 1.0 MPa O₂, 1 h reaction). Reproduced with permission from Ref^[42]. Copyright 2021, Royal Society of Chemistry; (D) Proposed reaction process of photocatalytic CH₄ oxidation on Au/TiO₂ and Au-CoO_x/TiO₂ using O₂ as the oxidant; (E) •OH production of photocatalysts in 1 mM coumarin aqueous solution; (F) In situ EPR spectra of Au-CoO_x/TiO₂ in CH₃OH aqueous solution dissolving O₂ with different light illumination times. Reproduced with permission from Ref^[31]. Copyright 2020, American Chemical Society. EPR: Electron paramagnetic resonance; DMPO: 5,5-dimethyl-1-pyrroline N-oxide; UV: ultraviolet.