Metal‐Support Interaction Boosts the Photocatalytic Performance of Pd/TiO ₂ for Acetylene Semi‐Hydrogenation: Modulating the H ^* Reaction Behavior and Ethylene Desorption

Abstract Photocatalytic acetylene (C ₂ H ₂ ) semi‐hydrogenation reaction is an environmentally friendly process for ethylene (C ₂ H ₄ ) production. However, all attempts to enhance the C ₂ H ₄ yield have faced kinetic limitations. Electronic metal‐support interaction (EMSI) is an effective approach to enhance kinetic constants by regulating the adsorption and desorption capabilities of intermediates and reactive species, promoting the reaction in the forward direction. Herein, Pd/TiO ₂ catalysts are constructed by a hydrothermal‐calculation method, forming the EMSI effect between Pd and TiO ₂ . Spectroscopy characterizations and theoretical calculations demonstrate that EMSI promotes the photo‐generated charge carriers from TiO ₂ to Pd. The control of the local electron density on Pd nanoparticles directly influenced the Gibbs free energy of the H ^* reaction and the desorption energy of ^* C ₂ H ₄ . This ultimately enhances the consumption and adsorption kinetics of H ^* , while simultaneously suppressing H ^* desorption and facilitating the desorption of ^* C ₂ H ₄ . Consequently, it modulates the preferential order between H ₂ evolution and the C ₂ H ₂ semi‐hydrogenation, expediting the production of C ₂ H ₄ . Therefore, the Pd/TiO ₂ achieves 99.7% C ₂ H ₂ conversion, 77.3% C ₂ H ₄ selectivity, and TON _C2H4 = 5960 within 3 h. This work provides a reference and guidance for the subsequent construction of efficient photocatalytic C ₂ H ₂ semi‐hydrogenation catalysts.