Selective Electroreductive Amination of 5-HMF Enabled by Facet-Engineered Frustrated Lewis Pair-Type Oxygen Vacancies on CeO2 Nanocrystals.

Electrocatalytic construction of C─N bonds from biomass-derived platform molecules offers a sustainable route to value-added nitrogen-containing chemicals. In particular, the electrocatalytic reductive amination (ERA) of 5-hydroxymethylfurfural (5-HMF) with ethanolamine provides a green alternative to conventional reductive amination by circumventing the use of high-pressure H2 and stoichiometric chemical reductants. Herein, we report a facet-regulated CeO2 catalyst that preferentially exposes vacancy-derived frustrated Lewis pair (FLP) sites on the (100) surface, enabling highly efficient and selective ERA to produce 2-[(5-(hydroxymethyl)furan-2-yl)methylamino]ethanol (HEMF). The optimized catalyst delivers 100% HEMF selectivity and a Faradaic efficiency of 99% at a current density of 20 mA cm-2. Electrochemical measurements, high-resolution transmission electron microscopy, temperature-programmed desorption, and in situ ATR-SEIRAS reveal that the vacancy-derived FLP sites promote the cooperative adsorption of the imine intermediate and activation of its C═N bond, thereby highlighting the decisive role of vacancy configuration in governing catalytic performance. These findings establish vacancy-derived FLP sites as the key catalytic motifs for selective ERA and identify vacancy configuration engineering as an effective strategy for the rational design of highly efficient CeO2 electrocatalysts.