**4.1 Procedure for the PENQ: TiO2 nanosystems synthesis**

During the solvothermal synthesis method in a clean and dry beaker appropriate amount of titanium tetra-isopropoxide is stirred in methanol and minimum amount of hydrazine hydrate. To the another dry beaker guanidine carbonate is dissolved in acetic acid and added to the first beaker dropwise with continuous stirring for next 30 min. The PENQ which is taken for all the above compositions were taken from earlier reported methods. Further, all the solution is added to the Teflon coated autoclave reactor and kept at 145–150°C around 15-hour reaction time. Lastly, the solids were filtered and dried in vacuum oven. All the photocatalysts systems are well grinded in pestle mortar before the actual photocatalysis experiments.

## **4.2 Characterization of PENQ: TiO2 nanosystems**

This unique and hybrid nanosystems has been characterized further for phase identification. Powdered X-ray diffractometry (PXRD) tells the story about phase and crystal structure of given materials **Figure 3**. Highlights the PXRD of novel PENQ: TiO2 photocatalyst nanosystems materials. As the concentration of TiO2 over the surface of PENQ increases the peak intensity is also increases. Both the peaks are highlighted with the help of different shapes in the figure. Diffraction peaks which are present at θ = 25.28, 38.01, 47.9, 54.01 and 54.89 are can be indexed for (101), (004), (200), (105) & (211) planes by corresponding to JCPDS card No. 21-1272 which confirms the Anatase TiO2. Furthermore, the PXRD peaks θ =14.4, 23.3 & 27.9° are due to the following planes (012), (112) & (104) which matches with the monoclinic crystal structure phase of PENQ. The JCPDS card No.47-2123 is corresponds to monoclinic PENQ in previous reports.

Also, PXRD width in the peaks of inorganic material (TiO2) highlights the reduction of particle sized to nano level, these sizes are in the range from 5 to 10 nm. After PXRD study same powdered samples were also analyzed using SEM analysis which is shown in the **Figure 2** (a and b). From the SEM pictures it can be clearly seen that these clear PENQ images are having size in the range of 60–250 nm thickness.

Further, SEM pictures of first nanocomposite system for 5 mmol showed the formation very tiny nanoparticles of 5 nm TiO2 on all over the flakes of organic PENQ sheets. On the other hand, for 10 and 17 mmol nanocomposites systems are showing 6–10 nm sizes, respectively (2 e-h). All the above SEM micrographs shows the uniform stacking of nanoparticles on the surface of sheet like PENQ photocatalyst material. From these images it is observed that the comparative density of nanomaterials is increases as the concentration of TiO2 is increases.

After the morphological analysis using SEM study nanosystems were subjected to for TEM characterization and SAED pattern analysis as shown in the **Figure 3**. From

**Figure 3.** *XRD and UV diffraction analysis. Reproduced with copyright permission from Royal Society of Chemistry.*

**Figure 4.** *FESEM and TEM analysis. Reproduced with copyright permission from Royal Society of Chemistry.*

the TEM photos it is clear that the nano sized round particles of TiO2 are responsible for the covering of all the sheets of PENQ with 3 nm size. It is observed that at higher concentration of mmol the size of TiO2 is also increases from 3 to 10 nm and covers the sheets like surface of PENQ. Clear and prominent lattice fringes can be seen in high resolution TEM photos (in the **Figure 3b, d** and **f**) with 0.33 nm of inter-planer distance in between the planes corresponds to (101) crystal planes of inorganic nano TiO2. The ED (Energy Dispersive) patterns clearly shows the high intense rings which also increases from 5 mmol to 17 mmol. When these round particles showed the close connection over the surface gives idea about the effective charge migration mechanism during the catalytic reactions (**Figure 4**).

*Organic Semiconductor for Hydrogen Production DOI: http://dx.doi.org/10.5772/intechopen.107008*

For optical study diffuse reflectance UV-Visible (UV-DRS) absorbance spectra of PENQ and TiO2 is given in **Figure 3**. The pure PENQ takes the absorbance edge at 450, 451 attributed the band gap around 2.9 and 2.7 eV. Band gap of TiO2 in 10 mmol and 17 mmol is high because of blue shift in nano particle.
