The limitations of TiO₂ as a photocatalyst such as the larger bandgap energy, which only activates under the UV region, give a lower photocatalytic activity. This study reports the role of the N and Pt co-dopant on the modification of the TiO₂ photocatalyst for photocatalytic degradation of methylene blue dye under different mode preparations, i.e., sequential and vice-versa modes. The sequential mode preparation of the N and Pt co-dopant TiO₂ photocatalyst consisted of the initial preparation of the N-doped TiO₂ (N-TiO₂) under the calcination method, which was then further doped with platinum (Pt) through the photodeposition process labeled as NP_seq-TiO₂, while the vice-versa mode was labeled as PN_rev-TiO₂. About 1.58 wt.% of N element was found in the NP_seq-TiO₂ photocatalyst, while there was no presence of N element detected in PN_rev-TiO₂, confirmed through an elemental analyzer (CHNS-O) and (EDX) analysis. The optimum weight percentage of Pt for both modes was detected at about ±2.0 wt.%, which was confirmed by inductively coupled plasma-emission spectroscopy (ICP-OES). The photoactivity under methylene blue (MB) dye degradation of the NP_seq-TiO₂ photocatalyst was 2 and 1.5 times faster compared to the unmodified TiO₂ and PN_rev-TiO₂, where the photodegradation rates were, ca., 0.065 min⁻¹ and 0.078 min⁻¹, respectively. This was due to the N elements being incorporated with the TiO₂ lattice, which was proven by UV-Vis/DRS where the bandgap energy of NP_seq-TiO₂ was reduced from 3.2 eV to 2.9 eV. In addition, the N generated a stronger PL signal due to the formation of oxygen vacancies defects on the surface of the NP_seq-TiO₂ photocatalyst. The higher specific surface area as well as higher pore volume for the NP_seq-TiO₂ photocatalyst enhanced its photocatalytic activity. Moreover, the NP_seq-TiO₂ showed the lowest COD value, and it was completely mineralized after 7 h of light irradiation. The preparation order did not affect the Pt dopant but did for the N element. Therefore, it is significant to investigate different mode preparations of the N and Pt co-dopant for the modification of TiO₂ to produce a good-quality photocatalyst for photocatalytic study under the photodegradation of MB dye.

Polyaniline (PANI) and Kronos C doped Titanium dioxide (TiO₂) was fabricated as PANI/TiO₂ solar cell and reported on its simple photovoltaic performance detected by using voltameter and tested for stability for 12 months. The PANI and TiO₂ were coated onto different indium tin oxide (ITO) glass plates by using a drop-casting method and sandwich attached for simple solar cell preparation. PT4 sample was the optimum solar cell with 0.2: 0.2 g of PANI: TiO₂ ratio under 2 cm² surface area based on the highest voltage produces from 100 mW cm^-1 of light intensity metal highlight lamp. No voltage was detected for PT7 where the single layer TiO₂ coated without PANI attached for solar cell system using same fabrication. It shows that PANI has a significant role in functionalizing the photovoltaic system. The C-N stretching of aromatic amine and C-N stretching for the benzenoid at peaks of 1222 and 1166 cm^-1 respectively in FTIR spectra has confirmed the PANI structure supported by an XRD pattern. TP4 has the highest photovoltaic performance compared to other types of TiO₂ based on the electron lifetime (τe) and the voltage produced was sustained up to 12 months.

The textile industry is suffering a great challenge regarding wastewater management, primarily due to the implementation of improper systems, specifically for dye wastewater treatment. Photocatalysis is one of approaches that have been used to treat wastewater. Titanium dioxide (TiO₂) was immobilized by using the dip-coating technique in this research. Epoxidized natural rubber (ENR) and polyvinyl chloride (PVC) were used as a polymer to bind the TiO₂ on the glass substrate. This immobilized TiO₂/ENR/PVC underwent a photoetching process at various times to study the crosslink and porosity formations. Reactive red 4 dye was used as a model pollutant for photocatalytic performance. All immobilized TiO₂/ENR/PVC samples under 12, 24 and 30 h of photoetching process (TEP12, TEP24 and TEP30 samples, respectively) showed higher photocatalytic activity compared to those without photoetching process (TEP0 sample) due to the intermediate charge in crosslinking reaction after the photoetching process. The TEP24 sample showed the highest photocatalytic degradation; light harvesting; photocatalytic degradation.

Titanium dioxide (TiO 2 ) was immobilized by using the dip-coating technique in this research. Epoxidized natural rubber (ENR) and polyvinyl chloride (PVC) were used as a polymer to bind the TiO 2 on the glass substrate. This immobilized TiO 2 /ENR/PVC underwent a photoetching process at various times to study the crosslink and porosity formations. Reactive red 4 dye was used as a model pollutant for photocatalytic performance. All immobilized TiO 2 /ENR/PVC samples under photoetching process were showed higher photocatalytic activity compared to those without photoetching process (TEP0 sample). TEP24 sample has shown the highest photocatalytic degradation where the 1 st order rate constant (k) value was 0.1066 min -1 which is 7 times faster as compared with TEP0. The increment of photocatalytic degradation of TEP24 also due to the significant increment of porosity and the formation of C-O-C aliphatic from crosslinking reaction of ENR/PVC or ENR/ENR from the FESEM and FTIR analysis respectively. XPS analysis was performed to support the FTIR where C-O-C aliphatic was detected on TEP24. The electron injection of TEP24 was identified from PL analysis due to the present of C-O-C aliphatic. The crosslink reaction has increased the durability of the immobilized TiO 2 /ENR/PVC where it can be reused for more than 30 cycles.