TiO2 nanotube/Ag-AgBr three-component nanojunction for efficient photoconversion

A TiO2 nanotube/Ag-AgBr three-component nanojunction with enhanced visible-light activity was synthesized by a two-step approach including an electrochemical anodization technique followed by an in situ photo-assisted dipping and deposition approach. Ag/AgBr nanoparticles with good dispersion were effectively deposited on both the inside and outside of the TiO2 nanotubes. Surface photovoltage measurements and luminescence spectra demonstrated that the Ag/AgBr loading enhanced the visible spectral absorption of TiO2 nanotube arrays, as well as their separation efficiency of photoinduced electron-hole pairs, which may due to the nanojunction built between Ag/AgBr and TiO2 in this system. The photoelectrochemical investigations verified that the TiO2 nanotube/Ag-AgBr nanojunction showed enhanced photocurrent generation efficiency and had a more effective photoconversion efficiency of 0.71% than the aligned TiO2 nanotube arrays alone. The enhanced photoelectrochemical properties can be attributed to the extended absorption in the visible light region resulting from Ag/AgBr nanoparticles, and the effective separation of photogenerated carriers driven by the photoinduced potential difference generated at the TiO2/Ag-AgBr nanojunction interface.