Photocatalytic Oxidative Coupling of Methane over Au1Ag Single‐Atom Alloy Modified ZnO with Oxygen and Water Vapor: Synergy of Gold and Silver.

C−H dissociation and C−C coupling are two key steps in converting CH4 into multi‐carbon compounds. Here we report a synergy of Au and Ag to greatly promote C2H6 formation over Au1Ag single‐atom alloy nanoparticles (Au1Ag NPs)‐modified ZnO catalyst via photocatalytic oxidative coupling of methane (POCM) with O2 and H2O. Atomically dispersed Au in Au1Ag NPs effectively promotes the dissociation of O2 and H2O into *OOH, promoting C−H activation of CH4 on the photogenerated O− to form *CH3. Electron‐deficient Au single atoms, as hopping ladders, also facilitate the migration of electron donor *CH3 from ZnO to Au1Ag NPs. Finally, *CH3 coupling can readily occur on Ag atoms of Au1Ag NPs. An excellent C2H6 yield of 14.0 mmol g−1 h−1 with a selectivity of 79 % and an apparent quantum yield of 14.6 % at 350 nm is obtained via POCM with O2 and H2O, which is at least two times that of the photocatalytic system. The bimetallic synergistic strategy offers guidance for future catalyst design for POCM with O2 and H2O. [ABSTRACT FROM AUTHOR]