Hydrothermal growth of nanorod arrays and in situ conversion to nanotube arrays for highly efficient Ag-sensitized photocatalyst

• TiO2 NRAs were hydrothermally grown on FTO substrate, and were in situ converted into NTAs by hydrothermally etching.
• Novel Ag-TiO2 NTAs with high specific surface area were successfully synthesized.
• The Ag-TiO2 NTAs showed dramatic photocatalytic activity than Ag-TiO2 NRAs, pure TiO2 NTAs, and NRAs.
• Improving activity is from a combination of SPR effect and high specific surface area effects.

TiO2 nanorod arrays (NRAs) were hydrothermally grown on transparent fluorine-doped tin oxide (FTO) substrates, and were converted into nanotubes (NTAs) by hydrothermally in situ etching. Ag nanoparticles (NPLs) were sensitized on the NRAs and NTAs by a simple photodeposition approach (products were denoted as Ag-TiO2 NRAs and NTAs). The Ag-TiO2 NTAs samples possessed a large specific surface area (116 m2 g-1) with Ag NPLs homogeneously dispersed among the TiO2 NTAs. The Ag-TiO2 NTAs exhibited significantly enhanced photocatalytic activities (98.8%) in degradation of methyl orange (MO) compared to Ag-TiO2 NRAs (92.6%), TiO2 NTAs (86.2%), and NRAs (81.7%). The enhanced photocatalytic activities can be attributed to the large specific surface area of TiO2 NTAs and strong surface plasmon resonance (SPR) of Ag NPLs. In addition, Ag-TiO2 NTAs showed easy recovery feature in the recovery process and high durability in the recycling test, which was expected to be an efficient and practical photocatalyst used for waste water treatment.

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