Size-Engineered Highly Active and Stable Pd/TiO ₂ Photocatalysts for Selective Oxidative Dehydrogenation of Ethane

Photocatalytic oxidative dehydrogenation of ethane (ODHE) offers a promising strategy for ethylene production under mild conditions. However, achieving a high ethylene yield and selectivity remains challenging due to the high activation barrier of ethane C–H bonds and the propensity for overoxidation to CO 2 . Herein, we demonstrate that Pd/TiO 2 -6, a palladium-decorated, 6 nm-sized TiO 2 support, functions as a selective photocatalyst for ODHE using O 2 under continuous-flow conditions. The optimized Pd/TiO 2 -6 catalyst exhibits an ethylene production rate of 69.9 mmol g –1 h –1 with 78.9% selectivity and a high apparent quantum efficiency of 17.9%. It also demonstrates robust stability over 45 h of continuous operation, outperforming most reported photo- and thermocatalysts. In situ and time-resolved characterizations revealed that the highly dispersed, oxidized Pd species serve as essential mediators in promoting charge separation and enabling moderate oxygen activation. This synergistic effect enables the selective activation of C 2 H 6 to form key *C 2 H 4 intermediates, ultimately leading to a high ethylene formation rate. This work reveals key insights into preparing highly efficient ODHE photocatalysts by harnessing the support size effect.