Rationally Designed Water Enriched Nano Reactor for Stable CO2 Hydrogenation with Near 100% Ethanol Selectivity over Diatomic Palladium Active Sites

CO2 (CO) hydrogenation presents the widest route to synthesis of various valuable organic molecules, but precise carbon-carbon coupling control to targeted products along with the elimination of byproducts remains a challenge. We overcome these limitations by synthesizing a CeO2-supported dual Pd site catalyst that could actively catalyze CO2 conversion into single product ethanol almost without C1 byproducts in a continuous flow fixed-bed reactor. This surprising finding is derived from the observation that the synergistic catalysis between dual Pd atoms leads to extraordinary ability for the cleavage of C-O bond in *CHxOH species and the carbon-carbon coupling between *CHx and *CO species. Furthermore, the dual Pd sites could be stabilized through enriching in situ formed water in the nano reactor with a hydrophobic shell layer, thus leading to remarkably improved catalytic stability for ethanol production. As a result, the as-constructed dual Pd site catalyst exhibited superior selectivity to ethanol at 98.7%, corresponding to a productivity up to 11.6 g per gram of Pd per hour and excellent stability during the continuous test for 60 h. Our results demonstrate that multifunctional synergistic catalysis of dual active sites can break through the restriction of a reaction involving a single active site catalyst.