Suppressing Reductive Deactivation of Fe ₂ O ₃ via In─O─Fe Motif Formation for CO ₂ Hydrogenation

Abstract

ABSTRACT 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 Fe 2 O 3 inevitably converts to Fe 3 O 4 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 In 2 O 3 /Fe 3 O 4 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 Fe 3 O 4 reinforces electronic delocalization, thereby stabilizing the intermediate and poisoning the surface. The In‐modified catalyst delivers nearly twofold higher CO yield than Fe 2 O 3 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 CO 2 hydrogenation.