Bi₂TiO₄F₂ nanosheets with abundant polarity surfaces make them a good candidate photocatalyst for CH₄ activation. Decorated with AuPd alloy nanoparticles, highly efficient CH₄ to CH₃OH transformation of 277.32 μmol g⁻¹ h⁻¹ with 93.5% selectivity is achieved over a AuPd/Bi₂TiO₄F₂ nanosheet photocatalyst, which is 7.4 times higher than that of the pristine Bi₂TiO₄F₂ nanosheets.