Tracking Dynamics of Supported Indium Oxide Catalysts in CO ₂ Hydrogenation to Methanol by In Situ TEM

Abstract

Abstract Supported reducible oxides, such as indium oxide on monoclinic zirconia (In 2 O 3 /m‐ZrO 2 ), are promising catalysts for green methanol synthesis via CO 2 hydrogenation. Growing evidence suggests that dynamic restructuring under reaction conditions plays a crucial but poorly understood role in catalytic performance. To address this, the direct visualization of the state‐of‐the‐art In 2 O 3 /m‐ZrO 2 catalyst under CO 2 hydrogenation conditions ( T   =  553 K, P   =  1.9 bar, CO 2 :H 2   =  1:4) is pioneered using in situ scanning transmission electron microscopy (STEM), comparing its behavior to In 2 O 3 on supports with similar (tetragonal, t‐ZrO 2 or anatase TiO 2 ) or lower (LSm‐ZrO 2 ) surface areas. Complementary in situ infrared spectroscopy and catalytic tests confirm methanol formation under equivalent conditions. A machine‐learning‐based difference imaging approach differentiates and ranks restructuring patterns, revealing that partially reduced InO x species on m‐ZrO 2 undergo cyclic aggregation‐redispersion via atomic surface migration, maintaining high active phase dispersion. High‐resolution ex situ STEM analysis further shows the epitaxial formation of In 2 O 3 mono‐ and bilayers on (100) m‐ZrO 2 facets, highlighting strong oxide‐support interactions. In contrast, sintering prevails on t‐ZrO 2 , a‐TiO 2 , and low‐surface m‐ZrO 2 , correlating with lower methanol productivity. This work underscores the pivotal role of oxide‐support interfacial interactions in the reaction‐induced restructuring of InO x species and establishes a framework for tracking nanoscale catalyst dynamics.