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 singleatom alloy nanoparticles (Au1Ag NPs)-modified ZnO catalyst via photocatalytic oxidative coupling of methane (POCM) with O-2 and H2O. Atomically dispersed Au in Au1Ag NPs effectively promotes the dissociation of O-2 and H2O into *OOH, promoting C H activation of CH4 on the photogenerated O to form *CH3. Electrondeficient 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 mmolg(-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 O-2 and H2O.

Automated summary

Atomically dispersed Au single atoms in Au1Ag NPs effectively promote the dissociation of O2 and H2O, facilitating the activation of CH4 to form C2H6. Electron-deficient Au single atoms also aid in the migration of electron donor from ZnO to Au1Ag NPs, leading to the coupling of *CH3 on Ag atoms of Au1Ag NPs.