Effects of NH4F and distilled water on structure of pores in TiO2 nanotube arrays

Abstract

In this study, we report the influences of distilled water and ammonium fluoride (NH4F) on morphology of pores in honeycomb-like titanium dioxide (TiO2) nanotube arrays. We observed the structure and arrangement of pores in the TiO2 nanotube arrays based on scanning electron microscopy images and analyzed the spatial distribution of the pores using fast Fourier transform and Voronoi diagram. We studied the individual pore properties including pore diameter, wall thickness, and interpore distance and found that locally connected ordering defects decreased with increasing distilled water concentration. Furthermore, we found that the optimum conditions of well-ordered hexagonal pore arrangement were 2 and 10 vol% distilled water with 0.2 and 0.4 wt% NH4F, respectively. Throughout this study, we provide a better understanding about the roles of distilled water and NH4F in forming well-ordered nanoscale pore structure with less ordering defects in the honeycomb-like TiO2 nanotube arrays.

Suitability of Different Titanium Dioxide Nanotube Morphologies for Photocatalytic Water Treatment

“…The first generation of anodic nanotubes is represented by TiO 2 NT-P, whereas TiO 2 NT-S belongs to the second generation. Titanium dioxide formed in the organic electrolyte ethylene glycol (TiO 2 NT-O) forms part of the third generation fluoride-containing electrolytes [ 28 , 29 ]. The photocatalytic efficiency of these three surfaces was assessed and the most suitable material for water treatment was identified.…”

Modification of charge transport in nanostructured TiO2−x Schottky diodes via post fabrication annealing

“…Although there are many techniques to prepare TiO 2 -NTs, such as sol-gel and template assisted methods, electrochemical anodization offers a high control over the pore diameter, interpore distance, wall thickness, as well as the regularity and defect ratios. Recent studies, for example, have analyzed the effects of NH 4 F and water concentrations in an ethylene glycol electrolyte and reported on the optimum conditions to grow self-organized, hexagonally arranged NTs with a low defect ratio [5][6][7][8]. TiO 2 crystalizes into three distinct polymorphs where anatase is generally accepted to have higher electronic efficiencies in nanostructures compared to its rutile and brookite phases.…”

Formation of the hollow nanopillar arrays through the laser-induced transformation of TiO2 nanotubes

“…The titanium dioxide nanotubes (TiO 2 NTs) have been excessively studied for years since their first synthesis by Assefpour-Dezfuly et al 1 due to their excellent photocorrosion resistance 2 , non-toxicity, and outstanding optical properties 3 . Moreover, the TiO 2 NTs exhibit very high surface area and have easily tuneable nanotube length 4 , spacing 5,6 , and pore size [7][8][9] , all influencing properties of the nanotube array. Because of that, they have found immense success in research involving gas sensors 10 , filtering systems 11 , solar cells 12 , and photocatalysis 13,14 .…”