Reaction-Induced Dynamic Evolution of In₂O₃ During the Reverse Water-Gas Shift (RWGS) Reaction

The In₂O₃ based catalysts are promising for the reverse water-gas shift (RWGS) reaction owing to their high selectivity. However, the dynamic structural and chemical evolution of In₂O₃ under reactive atmosphere remains poorly understood. Herein, we elucidate the nanoscale dynamic evolution of In₂O₃ during the RWGS reaction using in situ transmission electron microscopy (TEM), in situ X-ray diffraction (XRD), quasi in situ X-ray photoelectron spectroscopy (XPS), and in situ Raman spectroscopy. Our results reveal that In₂O₃ undergoes substantial surface reconstruction at the early reaction stage in an H₂/CO₂ atmosphere, forming mobile worm-like In₂O_3-x nanorods even at temperatures as low as 150°C. These nanorods migrate and grow, increasing in width from 2.6 nm at 150°C to 8.5 nm at 400°C. Following this early-stage transformation, the particle size of In₂O₃ remains almost unchanged. The system subsequently enters a steady stage, governed by a dynamic balance between oxygen-vacancy formation by H₂ reduction and vacancy ''re-filling'' by CO₂. This work thus verifies the reaction-induced dynamic evolution of In₂O₃ for the RWGS reaction, where hydrogen acts as a key promoter and reaction temperature serves as a critical accelerator.