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 µmol g_cat⁻¹ h⁻¹ and the CH₄ conversion rate of 2,374.6 µmol 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^δ− and O⁻ species together polarized the C–H bond, while the Au^δ− and O⁻ species jointly stabilized the CH₃ intermediates, which favored the coupling of CH₃ intermediate to photosynthesize C₂H₆ instead of overoxidation into CO_x. Thus, the design of dual active species is beneficial for achieving high-efficient CH₄-to-C₂H₆ photoconversion. [ABSTRACT FROM AUTHOR]