To study the synthesis and characterization of photocatalyst TiO 2 /SiO 2 nanocomposite prepared by Co-Precipitation method

. We report here the synthesis of Nanocomposites of TiO 2 /SiO 2 by the wet chemical method i.e. Coprecipitation method. The sample of TiO 2 and SiO 2 and composite of TiO 2 /SiO 2 calcined at 600 o C and were structurally analyzed by X-Ray Diffraction. The values of cell parameter, Wyckoff position, sites etc. of prepared samples were also calculated. The size of the crystal of TiO 2 /SiO 2 nanocomposites was obtained as 33.2 nm. The visualization of crystal structure of both TiO 2 and SiO 2 were also discussed in this paper.


Introduction
To meet the demand of many developing industries, a variety of small and big scale industries are thriving.These industries generate a lot of harmful chemical waste.These substances became dangerous for both aquatic and terrestrial life as a result of improper management and lack of knowledge [1].The nanocrystalline Tio2 has drawn constant attention because of its many uses in optical devices, sensors, catalysis, and photocatalysis, among others.It has several benefits, especially in dye sensitized solar cells.Large surface areas are needed for materials in dye sensitized solar cells in order to enable adequate light absorption and charge separations, which are the two crucial steps in the solar-electric conversion process.[2] Removing the color from industrial waste water is a topic of concern right now in every country on earth.One to twenty percent of the total amount of dye used is thought to be lost during the dying process and enters the receiving bodies [3].Titanium Oxide which is a semiconductor, frequently employed for photo catalysis because of its superior nontoxic, chemical stability, and cost-effective qualities [4].Photocatalytic property of TiO2 is influenced by size of crystal, phase of crystal, and surface area.Nano sized TiO2 can be synthesized by various techniques like Sol-gel, Sputtering, Combustion flame, and thermal plasma etc. [5] The purpose of adding amorphous SiO2 was because of its mechanical characteristics, superior adsorption capacity, and high surface area [6].
Numerous scientists want to boost the effectiveness of TiO2 photocatalytic activity.It is generally known that a good photocatalyst should have high specific surface area for absorbing and degrading the pollutants.And keeping this in mind, we use silica (SiO2) because of its large surface area and small pores and it might increase the TiO2 absorption capacity.
In 2010, Bellardita M et.al. prepared TiO2/SiO2 composite mesoporous nanomaterial.[7] In 2012, D. Arun Kumar et.al. prepared nanocomposites of TiO2/SiO2.They found that the surface area of TiO2 was 60m2/g.They also found that the surface area has raised more as a result of the composite SiO2 was formed.[8] In 2021, V Thongpool et.al. prepared nanocomposites of TiO2/ SiO2 by using the Sol Gel Method.When TiO2 engages in photocatalytic activity, it absorbs photon energy (hv), which causes electrons to move from the valence band to the conduction band, leaving holes in the former.Superoxide radicals are produced when electrons interact with the oxygen in the immediate vicinity (O2-)*, while hydroxyl radicals (OH*) were produced when holes contact with the water in the immediate vicinity.When photon energy interacts with hydrogen peroxide (H2O2), a hydroxyl radical (OH*) was also produced.The organic component is then broken down by this hydroxyl radical (OH*) into water (H2O) and carbon dioxide (CO2).[9] As per the above literature review, in the present work, it was reported that Nanocomposite of TiO2/ SiO2 was synthesized by the co-precipitation Method i.e. wet chemical precipitation Method.The results of prepared sample were observed with the help of XRD.The molecular and crystal structure of TiO2 and SiO2 were also discussed.

Synthesis of TiO2/SiO2
Three steps are required to produce the final product of nanocomposite i.e.TiO2/SiO2.These three steps are:- • Step 1:-TiO2 production: All chemicals were bought from the Sigma Aldrich firm.None of the compound were further purified or altered before being employed.The approach described in the literature was used to add the precursors at a controlled drop rate.[10] • Step 2:-Synthesis of Amorphous SiO2:-The suspension of amorphous silica dioxide (SiO2) was created using the procedure described in literature.[11] • Step 3:-For obtaining the final suspension of TiO2/SiO2, Step 1 was doped in the suspension of Step 2 and was mixed smoothly with the help of Stirrer for the seven hours at a constant speed.

XRD Analysis
XRD pattern of TiO2, SiO2 and TiO2/SiO2 calcined at 600 o C was shown in Figure 1.The parameters like hkl plane, size of crystal and intensity, Lattice strain, dislocation density of the TiO2/SiO2 was shown in Table 1.The final prepared sample contained peaks of TiO2 i.e. at 23.3 ∘ , 38.9 ∘ 43 ∘ , 55.1 ∘ , 62.6 ∘ was matched by JCPDS No. 711167.The XRD diffraction pattern of SiO2 showed the hump at around 21 o corresponding to the amorphous matrix with no certain crystalline peaks.The crystal size and dislocation density was calculated by formula given by equation 1 and 2 as mention below.Crystal size was evaluated by the Scherrer's formula:- And the Dislocation density was calculated by formula given below:- Fig.  The average size of the crystal of TiO2/SiO2 nanocomposites calculated by Scherrer's formula mentioned above and was obtained as 33.2 nm.The visualization of crystal structure of both TiO2 and SiO2 was shown in Figure 2. Atomic parameters i.e.Wyck.Position, x/a, y/b, z/c etc. value of the nanocomposite TiO2/SiO2 was shown in Table 2.

Conclusion
In this chapter, the nanocomposite of TiO2/SiO2 was prepared successfully.The average of crystal size was obtained as 33.

Table 1 .
Parameters of TiO2/SiO2 sample from X-Ray Diffraction Pattern