Atomically dispersed silver on nanosheet-stacked amorphous alumina for enhanced NOx reduction

Abstract

Tailoring anchoring sites in Al2O3 to strengthen metal-support interactions (MSI) remains a challenge yet essential for designing robust single-atom catalysts. Herein, nanosheet-stacked amorphous alumina (mAl2O3) with enhanced surface area and abundant hydroxyl groups was prepared by controlling the thermal treatment protocol of an Al-containing MOF. Loading 1 wt% Ag onto mAl2O3 led to atomically dispersed Ag species due to strong MSI, enabled by effective anchoring onto terminal hydroxyl groups uniquely distributed on mAl2O3, where both OH-μ1-AlIV and OH-μ1-AlVI sites coexist, unlike conventional Al2O3, predominantly featuring OH-μ1-AlVI alone. In hydrocarbon selective catalytic reduction, Ag(1)/mAl2O3 demonstrated markedly higher deNOx activity, exceptional water resistance, and durability. Detailed surface studies confirmed the facilitated formation of reactive enolic species and surface nitrates (NO3−) on Ag(1)/mAl2O3, which accelerated isocyanate (−NCO) formation, the key intermediate for selective NOx reduction. This work introduces an innovative method to produce Al2O3 with tunable surface structures, fostering highly active single-atom catalysts.