Influence of Ag-Au microstructure on the photoelectrocatalytic performance of TiO2 nanotube array photocatalysts

In this work, vertically-aligned TiO2 nanotube arrays (TiO2 NTs) were grown on Ti substrates via a facile electrochemical anodization method followed by calcinations. Then, Ag-Au alloy nanoparticles and Ag@Au core-shell nanoparticles were deposited on the obtained TiO2 NTs via UV reduction and displacement reaction, respectively. X-ray diffraction, scanning electron microscopy and transmission electron microscopy indicated that Ag-Au alloy nanoparticles and Ag@Au core-shell nanoparticles grew uniformly on the walls of TiO2 NTs. Investigation results from removal of methyl orange (MO) and Cr(IV) ions indicated that the as-prepared bimetal plasmonic photocatalysts exhibited excellent photoelectrocatalytic (PEC) activities. The influences of Ag-Au alloy and core-shell microstructures on PEC properties of TiO2 NTs were investigated and the TiO2 NTs/Ag@Au photocatalyst showed more outstanding PEC removal efficiency than that of TiO2 NTs/Ag-Au due to the regular core-shell microstructure and low recombination of photogenerated electrons and holes.