Effect of Multiply Twinned Ag Nanoparticles on Photocatalytic Properties of TiO Nanosheets and TiO Nanostructured Thin Films.

Ag-decorated TiO nanostructured materials are promising photocatalysts. We used non-standard cryo-lyophilization and ArF laser ablation methods to produce TiO nanosheets and TiO nanostructured thin films decorated with Ag nanoparticles. Both methods have a common advantage in that they provide a single multiply twinned Ag characterized by {111} twin boundaries. Advanced microscopy techniques and electron diffraction patterns revealed the formation of multiply twinned Ag structures at elevated temperatures (500 °C and 800 °C). The photocatalytic activity was demonstrated by the efficient degradation of 4-chlorophenol and Total Organic Carbon removal using Ag-TiO nanosheets, because the multiply twinned Ag served as an immobilized photocatalytically active center. Ag-TiO nanostructured thin films decorated with multiply twinned Ag achieved improved photoelectrochemical water splitting due to the additional induction of a plasmonic effect. The photocatalytic properties of TiO nanosheets and TiO nanostructured thin films were correlated with the presence of defect-twinned structures formed from Ag nanoparticles with a narrow size distribution, tuned to between 10 and 20 nm. This work opens up new possibilities for understanding the defects generated in Ag-TiO nanostructured materials and paves the way for connecting their morphology with their photocatalytic activity.