Unmatched Redox Activity of the Palladium-Doped Indium Oxide Oxygen Carrier for Low-Temperature CO₂ Splitting

Abstract

The chemical conversion of CO2 into value-added products is the key technology to realize a carbon-neutral society. One representative example of such conversion is the reverse water–gas shift reaction, which produces CO from CO2. However, the activity is insufficient at ambient pressure and lower temperatures (<600 °C), making it a highly energy-intensive and impractical process. Herein, we report indium oxide nanofibers modified with palladium catalysts that exhibit significantly potent redox activities toward the reduction of CO2 splitting via chemical looping. In particular, we uncover that the doped palladium cations are selectively reduced and precipitated onto the host oxide surface as metallic nanoparticles. These catalytic gems formed operando make In2O3 lattice oxygen more redox-active in H2 and CO2 environments. As a result, the composite nanofiber catalysts demonstrate the reverse water–gas shift reaction via chemical looping at record-low temperatures (≤350 °C), while also imparting high activities (CO2 conversion: 45%). Altogether, our findings expand the viability of CO2 splitting at lower temperatures and provide design principles for indium oxide-based catalysts for CO2 conversion.