Y-branched TiO₂Nanotubes Prepared by Electrochemical Anodization

Barrier-oxide layer engineering of TiO2 nanotube arrays to get single- and multi-stage Y-branched nanotubes: Effect of voltage ramping and electrolyte conductivity

“…3a). This value is significant and comparable to the previously reported branched nanostructures [37]. At 40-to-30 V ramping down process, only ∼40% branching (Inset of Fig.…”

“…The growth mechanism of Y-branching of TNAs, modeled and explained in terms of BOL thinning under non-steady-state regime, is reported for the first time. The main difference between the current report and all the previous reports that dealt with the TNA branching and stacking [17][18][19][20]26,27,[33][34][35][36][37] is that, most of these reports presented the engineering and electrochemical aspects of the branching in terms of the variations in the overall lateral dimension of the nanotubes, whereas, the current report presents a novel physicochemical aspect of the relative movement of the interfaces (electrolyte-TiO 2 and TiO 2 -Ti interfaces of the Ti-TiO 2 -electrolyte ternary system) across the BOL to create a 'pinching effect' to produce highly uniform branching. Therefore, the uniqueness of the current work is that, it deals with the dynamics of the BOL at the pore propagation front where the branching is actually initiated.…”

“…It is to be noted that the step (6) is one of the main reasons for the formation of titania nanotube arrays, whereas under comparable anodization conditions, ordered nanopores are formed in anodic alumina membrane. The overall oxidation and dissolution reactions during TNA growth are furnished below [8,37,41,42]:…”

“…This growth model is further justified by using several ramping steps as well as electrolytes (having different conductivity, imposed via aging processes) to get well-developed Y-branched as well as stacked double-layer of TNAs. Similar models have been adopted for the growth and BOL thinning of AAMs [37][38][39]. Yang et al [37] reported the formation of branched TNAs by reducing the anodization voltage and explained in terms of electric field distribution and 'core hole enlargement' at the nanotube growth front.…”

“…Similar models have been adopted for the growth and BOL thinning of AAMs [37][38][39]. Yang et al [37] reported the formation of branched TNAs by reducing the anodization voltage and explained in terms of electric field distribution and 'core hole enlargement' at the nanotube growth front. The voltage reduction changes the oxidation and dissolution equilibrium at the oxide barrier layer to create some 'core-holes' for the growth of branched nanotubes.…”