## 4 Discussion  
High-quality surfaces were produced using the three electrolytes and correspondingly different process parameters. The nanotube tops were completely etched open and devoid of any significant debris. The separation of the nanotubes produced in ethylene glycol into separate bundles shown in Figure 3C,D is due to the accelerated etching over the highly reactive grain boundaries. The grain boundaries are etched at a faster rate than the areas within the grain. The absence of this separation in Figure 3A,B is due to the lower potentials used. In Figure 3A,B, bright areas can be seen, which indicate that the nanotubes are growing over the high energy grain boundaries. The high potential used to produce TiO\({}_{2}\)NT and TiO\({}_{2}\)NT-Ag sustained a high dissolution rate, causing the separation of the tubes into bundles. The coverage of the TiO\({}_{2}\)NT-Ag surface with silver nanoparticles was relatively low, indicating that the dipping time was not sufficient or that the deposition could be aided by employing an electrophoretic method [28]. The effect of the potential on the layer thickness and tube diameter is immediately evident when the parameters presented in Table 1 are assessed. The higher potentials employed in the synthesis of TiO\({}_{2}\)NT-O and TiO\({}_{2}\)NT-Ag resulted in thicker arrays with wider tube diameters. The longer duration required for the production of TiO\({}_{2}\)NT-S resulted in a thicker layer than that in TiO\({}_{2}\)NT-P; however, the lower potential used still could not support the formation of layers as thick as those produced in ethylene glycol. The approximate elemental compositions presented in Table 2 show that the differences between TiO\({}_{2}\)NT, TiO\({}_{2}\)NT-S and TiO\({}_{2}\)NT-P are due to the electrolyte being used. The phosphorus and sulfur detected in TiO\({}_{2}\)NT-P and TiO\({}_{2}\)NT-S, respectively, indicate the impregnation of the structure with the electrolyte. The efficiency of the cleaning process is limited by the nanostructure in the material that is trapped within the tubes and requires a more laborious process for its complete removal. Similarly, the silver content in TiO\({}_{2}\)NT-Ag can be attributed to the component of the solution that did not coalesce to produce nanoparticles. This might limit the effect of the integration process as the silver in this shape might not be suitable to form the Schottky junction required for the increased charge transfer separation [29; 30]. Figure 9: Percentage survivability of various microorganisms classified according to their group. The application of electron-based antioxidant assays on TiO\({}_{2}\)-NT surface allowed for the determination of the surface activity towards the stabilisation of DPPH and ABTS radicals. Figure 3, Figure 5 and Table 3 show that surface synthesised at 20V (TiO\({}_{2}\)NT-S and TiO\({}_{2}\)NT-P) had a significantly lower rate of DPPH and ABTS radical stabilisation potential when compared to TiO\({}_{2}\)NT and TiO\({}_{2}\)NT-Ag. The stabilisation of these radicals was attributed to the photogenerated electrons, as well as other intermediates generated from the participation of the solvent and oxygen present in the solution. The latter reacted with surface generating free radicals stabilising ABTS\({}^{\bullet+}\) and DPPH radicals. This indicates that the surfaces produced in the organic medium had a higher electron and reactive oxygen species production rate. The direct interaction of the oxidizing agent with the excited conduction band electrons were considered for these molecular probe experiments. In the case of ABTS\({}^{\bullet+}\), the reaction was possible by considering the standard potential of ABTS\({}^{\bullet+}\) (Equation (1)) reduction coupled with water oxidation in aqueous media, along with the TiO\({}_{2}\) conduction band potentials (Equation (4)) as determined by [PERSON] [31] and [PERSON] [32].