Selective Photocatalytic Oxidative Ethane Dehydrogenation on AuPd Nanoparticle-Decorated TiO₂

Photocatalytic oxidative dehydrogenation of ethane offers a promising approach for producing ethylene under mild conditions. However, achieving high ethylene yields and selectivity is challenging due to the high C-H bond activation barrier in ethane and the tendency for overoxidation to CO₂. In this study, we demonstrate that TiO₂ with highly dispersed AuPd nanoparticles serves as an efficient and selective photocatalyst for the dehydrogenation of ethane with O₂ in a flow reactor. The optimized Au_0.33Pd_0.67/TiO₂ achieves up to 20.3 mmol g^-1 h^-1 of ethylene with 91.5% selectivity, resulting in a 5.9% apparent quantum efficiency at 365 nm. Detailed characterizations reveal that the Au_0.33Pd_0.67 cocatalyst plays a crucial role in facilitating photocarrier separation and regulating the formation of active oxygen species. Au_0.33Pd_0.67 effectively activates lattice oxygen of TiO₂, which serves as the localized oxidant to promote ethane dissociation through a photoassisted Mars-van Krevelen mechanism. Additionally, Au_0.33Pd_0.67/TiO₂ facilitates dioxygen reduction and ensures rapid oxygen replenishment in the TiO₂ lattice, thereby achieving a high yield of ethylene formation. This work provides valuable insights for designing composite photocatalysts for efficient and selective ethane oxidative dehydrogenation.