## 3 Results and Discussion
### Intensification by Photocatalyst Formulation  
Following Micro-Raman spectroscopy, a sample of pure MWCNT (C) showed the characteristic G, D peak and 2D (or G') bands (second-order two-phonon process), at 1340, 1580 and 2680 cm\({}^{-1}\), characteristic for carbon nanotubes, indicating stacking order (Figure 4). Glass fiber mesh alone does not show Raman bands (not shown). Titania sample (T) showed bands characteristic for TiO\({}_{2}\) at 148, 286, 399 and 633 cm\({}^{-1}\) assigned to anatase, with a very weak band at 286 cm\({}^{-1}\), possibly belonging to the rutile second order process [52]. Basically, TiO\({}_{2}\) bands dominate the composite sample (TiO\({}_{2}\)/CNT-GF). For TiO\({}_{2}\)/CNT-GF, sample bands related to MWCNT (D band and G band) are affected and appear at 1290 and 1620 cm\({}^{-1}\). A new band was observed at 1730 cm\({}^{-1}\) due to rearrangement of carbonaceous bonding due to specific MWCNT to mesh surface bonding (Figure 4a). The appearance of the band at 1730 cm\({}^{-1}\) is quite indicative in terms of achieving chemical bonds between the constituents in the TiO\({}_{2}\)/CNT-GF sample. In order to determine the bonding of the TiO\({}_{2}\) and MWCNT immobilized on fiber glass mesh, SEM analysis with different magnifications was performed on the TiO\({}_{2}\)/CNT-GF sample (Figure 4b). From the SEM results, it can be seen that a successful immobilization of TiO\({}_{2}\) and MWCNT on carriers occurred. Note that immobilization is not uniform: some parts of fibers are coated with TiO\({}_{2}\)/CNT aggregates, while others appeared clean. However, they were still coated with nanoparticles along the whole length, which can be seen by detailed analysis of higher magnifications (results not shown). As shown in the embedded figure, bonding of TiO\({}_{2}\) and MWCNT is clearly observed at higher magnification (200,000\(\times\)), which is in correlation with the presumption given from Raman spectra. The DRS spectra of the samples clearly depict differences. From Figure 5a, one can observe that all samples exhibit photoabsorption in the range between 250 and 400 nm. The Kubelka-Munk function was applied to relatively enhance the absorption bands of different samples of photocatalytic films. Generally, different types of constituents display different behavior: e.g., MWCNT absorption is characteristic for conducting materials, while TiO\({}_{2}\) absorption is characteristic for semiconducting materials. In order to evaluate the type of transitions, extent of transitions and bandgaps for derived composite samples (with respect to the constituents), the Tauc equation was applied (Figure 5b). Namely, anatase is an unquestionably semiconducting material, and it is widely accepted as it undergoes indirect allowed transitions (n = 1/2) (bandgap near the value of 3.2 eV). Other constituents are generally not semiconducting materials but may hinder or contribute to the semiconducting behavior of the composite. For that matter, they may be evaluated as semiconductors, although they are generally not semiconductors. Therefore, conventional calcium silicate glass undergoes indirect  
Figure 4: (a) Raman spectra of the photocatalytic constituents and composite film on glass fiber mesh; (b) SEM image of TiO\({}_{2}\)/CNT-GF at 1000 magnification and 200,000\(\times\) (given as embedded figure). allowed transitions (n = 1/2) (bandgap near the value of 3.85 eV). Among carbon-based substances, depending on the treatment, MWCNT shows direct allowed transitions (n = 2) (bandgap value from 2.9 to 3.6 eV). Bandgaps determined from the Tauc plot show 3.22 and 3.48 eV for pure TiO\({}_{2}\) (T) and glass-fibre (GF) constituents, respectively. For the composite sample, different transitions were tested, and those that dominate (best describe the sample optoelectronic performance and photocatalytic behavior) were selected. For the TiO\({}_{2}\)/CNT-GF sample, the situation is somewhat ambiguous.