Stabilizing vacancy-rich In2O3 by isolated Cr species for durable CO2 hydrogenation

The over-reduction of the vacancy-rich In2O3 phase remains a critical challenge in CO2 hydrogenation over In2O3-based catalysts. Here, we demonstrate that a vacancy-stabilizing ensemble consisting of isolated Cr atoms embedded in the In2O3 lattice can simultaneously provide abundant surface Ov sites, excellent catalytic activity and outstanding structural stability under CO2 hydrogenation conditions. Through experimental and DFT investigations, we identify the active site to be Cr3+-[Ov]2-Inδ+, where paired Ov sites facilitate CO2 adsorption in a bridge configuration and subsequent hydrogenation to HCOO* intermediates. The optimized catalyst with 10 mol% Cr delivers a methanol yield 2.1 times higher than that on pristine In2O3 and maintains structural integrity without detectable metallic In° formation over 110 h time-on-stream, even after strongly reducing treatment. This work highlights the isolated-Cr-stabilized oxygen-vacancy-pair ensembles as an effective strategy to reconcile abundant active vacancies with structural durability in In2O3-based CO2 hydrogenation catalysts.