Heat Treatment Effect on Crystalline Structure and Photoelectrochemical Properties of Anodic TiO₂ Nanotube Arrays Formed in Ethylene Glycol and Glycerol Based Electrolytes

Abstract

The effect of annealing temperature on crystal structure of anodic titanium dioxide (ATO) layers prepared via anodization in the ethylene glycol and glycerol based electrolytes was studied. Then samples were annealed in air at the temperatures ranging from 400 to 1000 °C. The XRD measurements proved that a gradual phase changes from anatase to rutile occurs with increasing annealing temperature. The anatase-to-rutile transformation occurs between 500 and 600 °C. The changes in the average crystallite sizes of anatase and rutile occurring during heat treatment of ATO layers were correlated with the mechanism of rutile phase nucleation. It was found also that the transition to the rutile phase in the samples formed in the ethylene glycol based electrolyte is considerably retarded and takes place at higher annealing temperatures due to the higher content of the embedded fluoride ions. The photoelectrochemical performance of ATO layers were studied under pulsed UV illumination. Photocurrent vs. incident light wavelength and applied potential plots were recorded. The highest photocurrents were observed for the samples annealed at 400 °C, regardless the electrolyte. It was demonstrated that the decrease in photocurrent values is related with the decreasing amount of the anatase phase in ATO samples. The enhanced photocurrent response was observed for ATO layers decorated with Ag nanoparticles. The highest photoconversion efficiencies, determined by incident photon-to-current efficiency (IPCE) calculations, were observed for the wavelength of 350 nm.

Enhanced simultaneous PEC eradication of bacteria and antibiotics by facilely fabricated high-activity {001} facets TiO2 mounted onto TiO2 nanotubular photoanode

“…S2). As reported, the anatase-to-rutile phase transformation prefer to occurring at higher temperatures (Jarosz et al, 2015). The eroded {001} facets were due to the HF etching/ dissolution effect at high recalcination temperature (Zhang et al, 2011a).…”

Structural, Morphological, and Electrochemical Corrosion Properties of TiO2 Formed on Ti6Al4V Alloys by Anodization

“…TiO 2 is a polymorphic ceramic material, which could exist, in three well‐known structural forms: rutile (tetragonal), anatase (tetragonal), and brookite (orthorhombic). In the literature, the oxide layers elaborated by anodizing technique are mainly in an amorphous form, but can also contain some crystalline phases, depending on the anodizing parameters . The crystalline oxide phase can be the anatase, rutile, brookite, or a mixture of them, which can be obtained by anodizing under subsequent heat treatments.…”

Fast diffusion of silver in TiO2 nanotube arrays

“…This result reveals the highly crystalline nature of the TiO 2 nanotubes in accord with the SAED pattern. The heat treatment can lead to a transition of TiO 2 nanotubes from the amorphous phase to a crystalline phase, which has been observed by Jarose et al [32]. …”