Photocatalytic behaviour of anodised titanium using different cathodes

Abstract

In the last decades, titanium dioxide (TiO 2) has been widely researched, because of its applications in photocatalytic environmental pollution removal and in hydrogen generation. Hence, this work deals with the synthesis of titanium dioxide by anodising titanium sheets, however using different cathodes, which may induce differences in the composition and structure of the obtained oxide layers so that these suspected differences can be observed. All specimens were equally thermally treated after anodising to enhance their photocatalytic activity since this step allows the titanium dioxide to crystallise. Their morphology and crystal structure were characterised by X-ray diffraction and FTIR, and optical properties were characterised by ultraviolet-visible absorption spectroscopy. Furthermore, tests of their photocatalytic properties in the degradation of organic dyes were performed in order to have a first evaluation. Indeed, differences in the photocatalytic behaviour of the anodised specimens using different cathodes were found and evaluated.

Evolution of anodised titanium for implant applications

“…[ 147 ] performed anodic oxidation at 5 V and 10 V in NH 4 F/NaCl electrolyte to produce TiO 2 nanotubes. The diameters of nanotubes increased from 24-30 nm for 5 V to 35–53 nm for 10 V which matches trends in other studies with similar electrolytes [ 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 ]. Michalska-Domańska et al.…”

“…Hsu et al [147] performed anodic oxidation at 5 V and 10 V in NH 4 F/NaCl electrolyte to produce TiO 2 nanotubes. The diameters of nanotubes increased from 24-30 nm for 5 V to 35-53 nm for 10 V which matches trends in other studies with similar electrolytes [75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96]. Michalska-Doma nska et al [169] reported that the diameter of nanotubes did not grow linearly with applied voltage when fabrication was done at 30-60 V in ethanol-based electrolyte containing NH 4 F and deionised water.…”

“…5.2. Testing techniques to measure the anodic TiO 2 mechanical stability Titanium-based anodised implants will have a chemically roughened hard TiO 2 oxide layer on the surface (known as anodised titanium; either in microstructured or nano surfaced TNTs, or feasibly both [311,312]) to improve their durability [3,4,313,6,16,53,87,120,240,263,264]. The general perspective for mechanical stability of anodised titanium deduced from recent in vitro and in/ex vivo studies has been summarised in Table 3.…”

“…The anodising variables that influence the characteristics of the oxide layer are: (i) process parameters i.e. applied voltage, current density, anodising time, ultrasonic and stirring effect, bath temperature, types and concentration of electrolytes; (ii) alloying elements of titanium substrate; (iii) pre- and/or post-treatment such as acid/alkaline treatment [ 45 , 82 ], hydrothermal [ 83 , 84 , 85 ], heat [ 86 , 87 , 88 ], ultraviolet irradiation or photocatalytic [ 18 , 87 ], ultrasonic [ 50 , 89 ], microwave [ 44 , 90 ] also two-step oxidation [ 91 , 93 ].…”

“…The anodised titanium is a structurally an advanced semiconductor [ 87 , 167 , 332 , 335 , 336 ]. Precise electronic fitting of its electrochemical characteristics, which could reduce the high-sensitivity of χ 2 , could result in improved analysis of the porous anodic properties of the crystallised TiO 2 semiconductor, validating the measured surface stability in the electrochemical circuit, which was neglected in other studies [ 138 , 141 , 144 , 189 , 209 , 214 , 331 , 332 , 333 ].…”