Reaction-induced surface/subsurface indium species formation on ZrO2 for enhanced CO2 hydrogenation to methanol.

The complex structural evolution of oxide catalysts during CO2 hydrogenation presents both challenges and opportunities for optimizing catalytic performance. This study demonstrates reaction-induced transformation of In2O3 particles into InOx nanolayers and subsurface In-Zr-O solid solutions on ZrO2 (denoted as In-ZrO2@InOx), significantly enhancing methanol synthesis efficiency. Under CO2/H2 reaction conditions, mobile metallic In0 generated from H2 reduction drives redispersion of In2O3 into surface InOx nanolayers, while subsequent inter-diffusion between In0 and Zr(CO3)2 leads to the formation of subsurface In-Zr-O solid solutions. Through precise control of temperature, pressure, and gas composition, we achieve optimal distribution of three distinct In species: In2O3 nanoparticles, surface InOx nanolayers, and subsurface In-Zr-O solid solutions. The engineered In-ZrO2@InOx catalyst exhibits a methanol space-time yield of 1.1 gmethanol/gcat/h with remarkable stability over 600 hours at 300 °C. Our findings highlight the crucial role of both surface and subsurface oxide species in oxide-catalyzed reactions and demonstrate the effectiveness of reaction-driven restructuring strategies for catalyst optimization.