Interparticle Oxygen Species Migration Mediates Remote Activation for Photocatalytic Methane Coupling

ABSTRACT The photocatalytic oxidative coupling of methane (OCM) offers a sustainable pathway for converting methane into valuable C2 compounds under ambient conditions. We explore the movement of oxygen species in photocatalytic OCM, particularly the cooperative effects between inert supports loaded with Au and semiconductor compounds (ZnO/TiO 2 , ZTO). The experimental results demonstrate that the coexistence of Au and ZTO is essential for C 2 H 6 production, even without any direct interfacing between the two components. EPR characterization indicates that superoxide radicals (·O 2 − ) may migrate from ZTO to Au sites, forming active Au─O species which activate methane into methyl radicals (·CH 3 ) for subsequent coupling into C 2 H 6 . Interestingly, in the photocatalytic OCM system, the C 2 H 6 yield remained stable upon progressive reduction of the semiconductor content before eventually declining. This trend suggests saturation of ·O 2 − intermediates likely arising from the kinetic balance between generation and quenching of ·O 2 − , where the semiconductor mediates the conversion of O 2 and lattice oxygen to ·O 2 − . We interpret this self‐regulating phenomenon as an Oxygen‐Mediated Self‐Buffering (O‐MSB) mechanism.