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

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.