## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c} \hline \multirow{2}{*}{**Sample**} & **Concentration of** & **Heating** & **Duration of** & **Time Required to Fully Degrade** \\  & **TiO\({}_{2}\) Precursor (mM)** & **Temperature (\({}^{\circ}\)C)** & **Spraying (min)** & **500 ppm of Acetaldehyde under** \\  & & & & **UV Irradiation (min)** \\ \hline
1 & 3.42 & 460 & 12 & 700 \\
2 * & 6.83 & 460 & 12 & 90 \\
3 & 13.66 & 460 & 12 & 40 \\
4 & 6.83 & 500 & 12 & 90 \\
5 & 6.83 & 550 & 12 & 35 \\
6 & 6.83 & 460 & 6 & 800 \\
7 & 6.83 & 460 & 24 & 50 \\ \hline \end{tabular}  
* The standard parameters used in the preparation of TiO\({}_{2}\) layer on substrates by Spray-ILGAR method for the preparation of solar cells.  
\end{table} 
Table 2: Photocatalytic decomposition of acetaldehyde by using TiO\({}_{2}\) on stainless steel prepared by Spray-ILGAR technique using different concentrations of TiO\({}_{2}\) precursor, different heating temperatures and different spraying durations. Figure 4: XRD pattern of TiO\({}_{2}\) coated on stainless steel by Spray-ILGAR technique using 6.83 mM of titanium diisopropyloxide bis(acetylacetone) alcoholic solution and heated at 460 \({}^{\circ}\)C.  
Figure 5 shows the graph for the photocatalytic decomposition of acetaldehyde by using TiO\({}_{2}\) on stainless steel prepared by the Spray-ILGAR technique using different concentrations of TiO\({}_{2}\) precursor (3.42, 6.83 and 13.66 mM), heated at 460 \({}^{\circ}\)C and spraying time of 12 min. As expected, the sample prepared with TiO\({}_{2}\) precursor with concentration of 3.42 mM showed the slowest decomposition rate. The highest photodecomposition rate was shown by the sample prepared with TiO\({}_{2}\) precursor with concentration of 6.83 mM, instead of that by the sample prepared using 13.66 mM of TiO\({}_{2}\) precursor. As shown in the SEM results (Figure 2a,b), the sample prepared with 13.66 mM of TiO\({}_{2}\) precursor showed a very compact and dense layer. The compactness would have caused a decrease in the surface area, hence the lower photodecomposition rate. Figure 6 shows the graph for the photocatalytic decomposition of acetaldehyde by using TiO\({}_{2}\) on stainless steel prepared by the Spray-ILGAR technique using different heating temperatures (460, 500 and 550 \({}^{\circ}\)C), 6.83 mM of TiO\({}_{2}\) precursor and spraying time of 12 min. It was shown that the higher the heating temperature, the faster the decomposition rate. As discussed above, the possible cause for this could be caused by the crystallinity of the TiO\({}_{2}\). However, as the crystallinity could not be properly determined using XRD analysis carried out, the reason remains a hypothesis. Figure 5: Photocatalytic decomposition of acetaldehyde by using TiO\({}_{2}\) on stainless steel prepared by Spray-ILGAR technique using different concentrations of TiO\({}_{2}\) precursor (3.42, 6.83 and 13.66 mM), heated at 460 \({}^{\circ}\)C and spraying time of 12 min. Figure 6: Photocatalytic decomposition of acetaldehyde by using TiO\({}_{2}\) on stainless steel prepared by Spray-ILGAR technique using different heating temperatures (460, 500 and 550 \({}^{\circ}\)C), 6.83 mM of TiO\({}_{2}\) precursor and 12 min of spraying time. The photocatalytic decomposition of acetaldehyde by using TiO\({}_{2}\) on stainless steel prepared by the Spray-ILGAR technique using different spraying durations (6, 12 and 24 min), 6.83 mM of TiO\({}_{2}\) precursor and heating temperature of 460 \({}^{\circ}\)C is shown in Figure 7. Based on the graph, it can be seen that the sample prepared using 24 min of spraying time showed the highest photodecomposition rate, while the slowest was shown by the sample prepared using 6 min of spraying time. This pattern was expected, as when the sample was prepared using 24 min of spraying time, a dense and compact layer of TiO\({}_{2}\) was formed (Figure 3b), hence providing more TiO\({}_{2}\) to act as the photocatalyst.