Mn₃O₄/Pt Oxide‐on‐Metal Inverse Catalyst Facilitates Hydrogen Spillover for CO₂ Hydrogenation Reaction

Abstract Hydrogen spillover, the migration of metal‐activated hydrogen species across support surfaces, is key for many H‐related reactions. However, questions remain about how the metal/oxide interfaces affect hydrogen spillover and hydrogenation reaction. Here, we construct Mn 3 O 4 ‐on‐Pt(111) (Mn 3 O 4 /Pt(111)) inverse catalyst and Pt clusters‐on‐Mn 3 O 4 (Pt/Mn 3 O 4 ) catalyst, and image hydrogen spillover behavior using high‐pressure scanning tunneling microscopy. We find that the onset H 2 partial pressure for hydrogen spillover is two orders of magnitude lower at Mn 3 O 4 /Pt(111) than at Pt/Mn 3 O 4 . This structural promotion effect was leveraged to synthesize MnO x /Pt/C inverse catalyst by depositing MnO x on Pt nanoparticles, which exhibits a 1.8‐fold higher CO 2 conversion compared to conventional Pt/MnO x /C catalyst during CO 2 hydrogenation. Theoretical calculations reveal that the inverse catalysts promote hydrogen spillover via weaker H adsorption and a more favorable transition‐state geometry at interfacial Pt sites, particularly along the Pt─Mn─O pathway. The Pt/Mn 3 O 4 interfaces feature strong H binding on Pt δ ⁺ and high H diffusion barriers, which can be partially mitigated by CO co‐adsorption. These findings demonstrate that inverse structure offers both electronic and geometric advantages at the interfaces, enabling efficient hydrogen spillover for hydrogenation reactions.