The role of interfacial lattice Ag+ on titania based photocatalysis

Ag0/Ag+/TiO2 composites were prepared via alkalescent hydrothermal process in aqueous ammonia, and Ag+/TiO2 was prepared by eluting the Ag0 cluster from the Ag0/Ag+/TiO2 composites with K3[Fe(CN)6]/aqueous ammonia. Methyl orange (MO) and Rhodamine B (RhB) were used to test the photocatalytic activity of the photocatalysts. The photocatalytic activity of the composites was greatly improved after eluting Ag0 clusters from the Ag0/Ag+/TiO2 composites. Interfacial lattice Ag+ cations but not Ag0 clusters are responsible for improving the photocatalytic performance of the composites in this work. XPS measurement shows that the chemical state of the interfacial lattice Ag+ cation is different with the surface chemical adsorbed Ag+ cation. Surface chemical adsorbed Ag+ cation is invalid to promote the photocatalytic activity of TiO2 while Na+ cation can cancel the promotional effect of the interfacial lattice Ag+ cation by competitively occupying the interfacial lattice defects. The 2 h turn over numbers of the interfacial lattice Ag+ cations to the degradation of MO and RhB reach 8 and 10, respectively, which show that the interfacial lattice Ag+ cations act as recyclable catalytic sites but not one-time consumptive species.

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► Ag+/TiO2 was prepared by eluting the Ag0 cluster from the Ag0/Ag+/TiO2.
► Ag+/TiO2 shows higher photocatalytic activity than Ag0/Ag+/TiO2.
► Interfacial lattice Ag+ is crucial for the superior activity of Ag+/TiO2.
► Interfacial lattice Ag+ acts as recyclable catalytic sites in photocatalysis.