Modulating the anchoring states of Ag on TiO2 by SiO2 to boost the NH3-SCO activity over Ag-based catalysts

Ag-based catalysts show high activity in NH 3 -selective catalytic oxidation (NH 3 -SCO). The anchoring states of Ag species determines its valence and dispersion, thereby influencing the performance of Ag-based catalysts. Herein, we elucidated that the content and anchoring strength of the hydroxyl (OH) groups on support together affect the anchoring states of Ag. TiO 2 has few OH groups but high anchoring strength, the anchored Ag is in a highly dispersed oxidized state, while the unanchored Ag is aggregated in a metallic state (Ag 0 ), so it presents an unevenly sized dispersion and mainly in oxidized state. SiO 2 has abundant OH groups but weak anchoring, and can excessively agglomerate into large Ag 0 nanoparticles (Ag 0 NPs). Therefore, the introduction of SiO 2 can regulate the anchoring states of Ag on the TiO 2 support, making Ag presents highly dispersed Ag 0 NPs, thus following a reaction mechanism with lower energy barriers and significantly improving the NH 3 -SCO performance.