High-rate CH₄-to-C₂H₆ photoconversion enabled by Au/ZnO porous nanosheets under oxygen-free system

Photocatalytic CH4 coupling into high-valued C2H6 is highly attractive, whereas the photosynthetic rate, especially under oxygen-free system, is still unsatisfying. Here, we designed the negatively charged metal supported on metal oxide nanosheets to activate the inert C-H bond in CH4 and hence accelerate CH4 coupling performance. As an example, the synthetic Au/ZnO porous nanosheets exhibit the C2H6 photosynthetic rate of 1,121.6 mu mol g(cat)(-1) h(-1) and the CH4 conversion rate of 2,374.6 mu mol g(cat)(-1) h(-1) under oxygen-free system, 2 orders of magnitude higher than those of previously reported photocatalysts. By virtue of several in situ spectroscopic techniques, it is established that the generated Au delta- and O- species together polarized the C-H bond, while the Au delta- and O- species jointly stabilized the CH3 intermediates, which favored the coupling of CH3 intermediate to photosynthesize C2H6 instead of overoxidation into COx. Thus, the design of dual active species is beneficial for achieving high-efficient CH4-to-C2H6 photoconversion.