Bifunctional confinement strategy for sintering-resistant Ag catalysts: synergy of B2O3 electrophilicity and NH2-spacial limitation in steering C = O bond activation dynamics

A mesoporous SiO 2 -supported Ag catalyst co-modified with B 2 O 3 and amino groups (B/Ag@NH 2 −MS) was synthesized through the grafting of amino group onto silica and subsequent impregnation with 10 wt.% Ag and 5 wt.% B 2 O 3 . Density functional theory (DFT) calculations and Bader charge analysis showed that boron (B) doping triggered extensive electronic changes in the modified support. It implied that B atoms gained a partial positive charge, showing Lewis acidic nature, while nearby Ag atoms had a partial negative charge. This electronic redistribution led to a downward movement of the Ag d -band center and a decrease in the work function, which in turn modulated the binding energies of adsorbates and reduced the desorption barrier of MG. Such dual-site cooperation strengthened the adsorption and polarization of the DMO carbonyl group at the adjacent Ag and B sites, thus promoting the activation of the C = O bond. Moreover, the anti-sintering capacity of Ag nanoparticles could be ascribed to their efficient stabilization mechanism, resulting from the synergistic action of oxygen-bridged B/O/Ag species and –NH 2 functional groups.Consequently, it is noted that the catalyst is able to maintain a conversion of about 99% DMO and a selectivity of about 94% MG, and it was able to maintain a conversion rate of over 96% for >350 h. These observations highlight a dual-site electron synergy strategy for developing very active and long-lasting Ag catalysts for ester hydrogenation.