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

https://www.sciencedirect.com/science/article/abs/pii/S138589472507891X

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-Al_IV and OH-μ₁-Al_VI sites coexist, unlike conventional Al₂O_3, predominantly featuring OH-μ₁-Al_VI 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.