W Single‐Atom Catalyst for CH₄ Photooxidation in Water Vapor

Abstract Solar‐driven high‐efficiency and direct conversion of methane into high‐value‐added liquid oxygenates against overoxidation remains a great challenge. Herein, facile and mass fabrication of low‐cost tungsten single‐atom photocatalysts is achieved by directly calcining urea and sodium tungstate under atmosphere (W‐SA‐PCN‐m, urea amount m = 7.5, 15, 30, and 150 g). The single‐atom photocatalysts can manage H₂O₂ in situ generation and decomposition into ·OH, thus achieving highly efficient CH₄ photooxidation in water vapor under mild conditions. Systematic investigations demonstrate that integration of multifunctions of methane activation, H₂O₂ generation, and decomposition into one photocatalyst can dramatically promote methane conversion to C1 oxygenates with a yield as high as 4956 µmol g_cat⁻¹, superior to that of the most reported non‐precious photocatalysts. Liquid–solid phase transition can induce the products to facilely switch in from HCOOH to CH₃OH by pulling the catalyst above water with CH₃OH/HCOOH ratio from 10% (in H₂O) to 80% (above H₂O).