Effect of annealing on UV‐visible absorption and photoluminescence behavior of liquid phase deposited TiO₂ nanorods

Abstract

In this work, anatase and rutile TiO 2 nanorods were fabricated using one-step liquid phase deposition process, followed by heat treatment in the range 300-800°C.The direct and indirect band gap of the TiO 2 nanorods was estimated form optical absorption data which illustrated a red shift at higher temperatures owing to the different nature of excitons in anatase and rutile phases. The photoluminescence (PL) spectra revealed the presence of two main emission bands consisting of four peaks.It was found that two high-energy peaks located at 2.95-3.30 eV could be generated from exciton transitions from the conduction band to the valence band of TiO 2 nanorods, while two low-energy peaks located at 2.43-2.64 eV may arise from surface state transitions. The PL intensity firstly increased with temperature and at 500°C reached a maximum value, then decreased through increasing temperature up to 800°C. These variations in the intensity of PL emission could be explained in terms of changes in phase structure, crystallinity, and amount of the oxygen vacancies, which are all dependent to the annealing temperature based on X-ray diffractometer and X-ray photoelectron spectrometer studies. These results indicated that annealing temperature allows to manipulate the properties of TiO 2 nanorods for opto-electronic applications. K E Y W O R D Sannealing temperature, photoluminescence, polycrystalline TiO 2 nanorods, UV-visible absorption, XPS analysis 2430 |

Template Based Synthesis of Plasmonic Ag‐modified TiO2/SnO2 Nanotubes with Enhanced Photostability for Efficient Visible‐Light Photocatalytic H2 Evolution and RhB Degradation

“…[57] However, when the Ag content exceeds 4%, the great amount of Ag may cover the surface of TiO 2 /SnO 2 nanotubes beyond monolayer leading to an exponential decrease in the electric field intensity with increasing the distance between TiO 2 /SnO 2 nanotubes and surface of Ag nanoparticles. [43] Therefore, the electrons and holes cannot be separated effectively leading to a decrease in the photocatalytic activity.…”

“…Here, the LPD method was used to coat the walls of SnO 2 nanotubes with a thin layer of TiO 2 nanotubes. This method involved immersing an alumina membrane in a treatment solution of (NH 4 ) 2 SnF 6 for up to 4 h, and then dipping of obtained SnO 2 nanotube arrays in a solution of (NH 4 ) 2 TiF 6 for up to 4 h. The formation of hybrid TiO 2 /SnO 2 nanotubes can be described by the following chemical reactions: …”

“…Hence, the generated electrons would transfer from the TiO 2 to Ag nanoparticles due to the fact that the work function of TiO 2 (4.2 eV) is lower than that of Ag (4.52 to 4.74 eV), so conduction band of Ag nanoparticles behaves as a trap for photogenerated electrons . However, when the Ag content exceeds 4%, the great amount of Ag may cover the surface of TiO 2 /SnO 2 nanotubes beyond monolayer leading to an exponential decrease in the electric field intensity with increasing the distance between TiO 2 /SnO 2 nanotubes and surface of Ag nanoparticles . Therefore, the electrons and holes cannot be separated effectively leading to a decrease in the photocatalytic activity.…”

Enhanced photocatalytic hydrogen evolution by novel Nb-doped SnO2/V2O5 heteronanostructures under visible light with simultaneous basic red 46 dye degradation

“…The Figure 5(a) reveals that highly-ordered tubular structure, uniform and parallel to each other with an outer diameter of about 100 nm and a wall thickness of about 35 nm is formed in the alumina membrane pores by the LPD process. Hydrous-SnO 2 can be deposited in situ on the alumina membrane using both a hydrolysis equilibrium reaction of [SnF 6 ] 2− , and an F − consuming reaction of the alumina membrane, which act as scavengers for F − according to following reactions [32,33]:…”

Photocatalytic degradation evaluation of N-Fe codoped aligned TiO2 nanorods based on the effect of annealing temperature

“…To overcome the drawback of low photocatalytic efficiency, considerable efforts have been taken, such as dimensionality reduction [4], metal and non-metal doping [5], and semiconductor coupling [6]. Onedimensional (1D) TiO 2 nanostructures, including nanobelts, nanofibers, nanorods, nanowires, and nanotubes [7][8][9][10][11] can be considered as one of good 108…”