Suppressing Reductive Deactivation of Fe₂O₃ via In─O─Fe Motif Formation for CO₂ Hydrogenation

Transition-metal oxides are susceptible to over-reduction under hydrogen-rich conditions, thereby hindering intermediate turnover and accelerating deactivation. Embracing this reaction reality, we show that Fe₂O₃ inevitably converts to Fe₃O₄ during reverse water-gas shift (RWGS) at 300°C, yet can be reactivated by forming interfacial In─O─Fe motifs through in situ oxidation of indium (In). Operando and post-reaction analyses identify In₂O₃/Fe₃O₄ as the working architecture. At these interfaces, strong sp-sp orbital hybridization between In and O atoms weakens the C─O bond within surface formate and accelerates its decomposition, shortening its surface residence and leading to high stability. In contrast, Fe─O─C orbital conjugation in Fe₃O₄ reinforces electronic delocalization, thereby stabilizing the intermediate and poisoning the surface. The In-modified catalyst delivers nearly twofold higher CO yield than Fe₂O₃ and exhibits marked durability at 450°C (activity loss 6% versus 62%). Rather than preventing phase transformation by bulk lattice stabilization (e.g., doping heteroatoms/constructing high-entropy oxides), this interface-motif strategy rebuilds functionality on the reduced steady state of transition metal oxides, providing a concise route to durable CO₂ hydrogenation.