Highly efficient, selective, and stable photocatalytic methane coupling to ethane enabled by lattice oxygen looping.

Light-driven oxidative coupling of methane (OCM) for multi-carbon (C) product evolution is a promising approach toward the sustainable production of value-added chemicals, yet remains challenging due to its low intrinsic activity. Here, we demonstrate the integration of bismuth oxide (BiO) and gold (Au) on titanium dioxide (TiO) substrate to achieve a high conversion rate, product selectivity, and catalytic durability toward photocatalytic OCM through rational catalytic site engineering. Mechanistic investigations reveal that the lattice oxygen in BiO is effectively activated as the localized oxidant to promote methane dissociation, while Au governs the methyl transfer to avoid undesirable overoxidation and promote carbon─carbon coupling. The optimal Au/BiO-TiO hybrid delivers a conversion rate of 20.8 millimoles per gram per hour with C product selectivity high to 97% in the flow reactor. More specifically, the veritable participation of lattice oxygen during OCM is chemically looped by introduced dioxygen via the Mars-van Krevelen mechanism, endowing superior catalyst stability.