Plasmonic silver nanoparticles matched with vertically aligned nitrogen-doped titanium dioxide nanotube arrays for enhanced photoelectrochemical activity

Abstract

The plasmonic Ag nanoparticles match with vertically aligned N-doped TiO2 nanotube arrays, which display improving photoelectrochemical performance. N-doped anatase nanotube arrays are fabricated firstly, and then cubic Ag nanoparticles of diameter 5 nm are deposited on TiO2 nanotubes without organic additives at room temperature. X-ray photoelectron spectroscopy shows that the oxygen vacancies and N impurity are revealed in N-doped TiO2. The electrical properties of samples are investigated by systematic photoelectrochemical measurement. The charge transfer ability of TiO2, N-doped TiO2 and Ag/N-doped TiO2 is presented directly by Electrochemical impedance spectroscopy and Mott–Schottky measurement, respectively. The carrier density of Ag/N-doped TiO2 is higher 2 orders of magnitude enhancement of TiO2. Furthermore, its photocurrent responds rapidly with illumination owing to fast photoelectron transport. And photocurrent density is 0.14 mA cm−2 at 1.23 VRHE, which is the highest among samples. Finally, the mechanism of improving photoelectrochemical activity is schematically displayed. The plasmonic Ag/N-doped TiO2 composties are favorable for the separation for photoelectron-hole pairs and increasing electron transfer, leading to a considerably photoelectrochemical performance under sunlight. The modified nanotube arrays provide potential application in photoelectrochemical cell.