Ag-TiO2 nanotube arrays prepared by electrochemical deposition with high photocatalytic hydrogen evolution efficiency

Abstract

A series of Ag-TiO₂ nanotube catalysts were prepared by electrochemical deposition. Doping of Ag nanoparticles was regulated by adjusting the deposition voltage, which altered the photocatalytic performance of the sample. The electrochemical properties of the Ag-TiO₂ nanotubes were characterized using X-ray photoelectron spectroscopy, scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy, and ultraviolet–visible (UV–vis) diffuse reflection spectroscopy. PL and UV–vis spectroscopy showed that the Ag-TiO₂ nanotubes had a higher visible-light absorption activity and a lower photogenerated electron–hole pair recombination rate. SEM analysis showed that the highly ordered tubular structure of the TiO₂ nanotubes was not disrupted after electrochemical deposition, and the size and quantity of the Ag nanoparticles deposited on the TiO₂ nanotubes increased with increasing deposition voltage. The Ag-TiO₂ nanotubes prepared at a deposition voltage of 1 V exhibited the highest hydrogen evolution efficiency, with a theoretical hydrogen production rate of 12.59 µmol∙cm⁻²∙h⁻¹ under UV irradiation. This was 2.1-fold higher than that of pure TiO₂ nanotubes and was attributable to the local surface plasmon resonance effect of Ag nanoparticles, which enhanced the visible light absorption by the TiO₂ nanotubes.