Photocatalytic oxidative coupling
of methane (POCM) is a direct
way for the methane transformation into ≥C2 alkanes. However,
the typical oxygen activation path often leads to the formation of
strong oxidizing superoxide radical (O2–) species, which makes the whole reaction face serious selectivity
problems. Herein, we constructed N and oxygen vacancy dual active
sites on TiO2{001} nanosheets (TiO2–NVo) to regulate the oxygen activation pathway and achieve a
high activity and selectivity of photocatalytic OCM. Compared with
ordinary Au/TiO2{001} nanosheets, the alkane yields of
Au/TiO2–NVo are increased from 16 μmol
h–1 to 32 μmol h–1, and
the selectivity of alkanes increased from 61% to 93%. The performance
is superior when compared with the reported till date in photocatalytic
OCM in batch reactors. The superior performance originates from the
unique N–Vo dual active sites for synergistically
cleaving the detrimental O2– into desirable
mono-oxygen active species (O·–) to suppress
undesired overoxidation reaction. The formed O·– species from O2– dissociation, in turn,
is active for the selective H abstraction of CH4 into •CH3 to improve the subsequent C–C coupling reaction on
the Au nanocluster surface. This work provides a new approach of O2 dissociation to address the overoxidation of methane in an
aerobic environment for achieving highly selective CH4 conversion.