## 3 Results and Discussion
### Structure, Morphology, Surface and Spectroscopic Studies
In P25/Zn\({}_{0.15}\)Cd\({}_{0.85}\)S nanocomposite with P25:Cd ratio of 1:5 with an approximate diameter around 3 \(\upmu\)m, P25 particles are deposited onto the Zn\({}_{0.15}\)Cd\({}_{0.85}\)S nanoflowers surface, as shown in Figure 2g. The structural analysis of the P25/Zn\({}_{0.15}\)Cd\({}_{0.85}\)S nanocomposite with P25:Cd ratio of 1:5 is done by HRTEM. As shown in Figure 2h, the lattice of both TiO\({}_{2}\) and CdS can be clearly distinguished; the lattice planes correspond to (002) crystal plane with a \(d\)-spacing of 0.335 nm matching with the hexagonal structure of CdS, whereas the spacing of 0.352 nm can be ascribed to the (101) crystal face of anatase TiO\({}_{2}\). It can be clearly observed that the TiO\({}_{2}\) is deposited onto the nanoflowers substrate, which may promote a synergistic effect towards photocatalysis by enhancing a wide optical absorption and also ensure structural stability of the composite [29]. Figure 1: (a) XRD patterns of pure CdS nanoparticles, Zn\({}_{0.15}\)Cd\({}_{0.85}\)S nanoflowers and P25/Zn\({}_{0.15}\)Cd\({}_{0.85}\)S nanocomposite with P25:Cd of 1:10, 1:5 and 1:3, and the enlarged peaks corresponding to (**b**) (110) and (**c**) (112) crystal plane for CdS nanoparticles and Zn\({}_{0.15}\)Cd\({}_{0.85}\)S nanoflowers. The UV-vis absorbance spectra of the pure CdS, Zn\({}_{0.15}\)Cd\({}_{0.85}\)S nanoflowers and P25/Zn\({}_{0.15}\)Cd\({}_{0.85}\)S nanocomposite are shown in Figure 3. The band gaps are calculated according to the Kubelka-Munk \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sample Label** & **Molar Ratio P25 Cd** & **BET (m\({}^{2}\)g\({}^{-1}\))** & **Band Gap (eV)** \\ \hline CdS & - & 0.26 & 2.20 \\ Zn\({}_{0.15}\)Cd\({}_{0.85}\)S & - & 0.63 & 2.23 \\ P25/Zn\({}_{0.15}\)Cd\({}_{0.85}\)S 1-10 & 1:10 & 7.50 & 2.24 \\ P25/Zn\({}_{0.15}\)Cd\({}_{0.85}\)S 1-5 & 1:5 & 21.4 & 2.28 \\ P25/Zn\({}_{0.15}\)Cd\({}_{0.85}\)S 1-3 & 1:3 & 37.8 & 2.30 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Sample label, molar ratio, Bruauer–Emmett–Telle (BET) surface area, and band gap of pure CdS, Zn\({}_{0.15}\)Cd\({}_{0.85}\)S nanoflowers, and P25/Zn\({}_{0.15}\)Cd\({}_{0.85}\)S nanocomposite. Figure 2: Scanning electron microscopy images of (**a**) pure CdS nanoparticles, (**b**) Zn\({}_{0.15}\)Cd\({}_{0.85}\)S nanoflowers and (**c**) P25/Zn\({}_{0.15}\)Cd\({}_{0.85}\)S nanocomposite with P25:Cd of 1:10, (**d**) 1:5 and (**e**) 1:3, bright field TEM image of (**f**) Zn\({}_{0.15}\)Cd\({}_{0.85}\)S nanoflowers, and (**g**) P25/Zn\({}_{0.15}\)Cd\({}_{0.85}\)S 1-5 and (**h**) HRTEM image of P25/Zn\({}_{0.15}\)Cd\({}_{0.85}\)S 1-5.  
model [30] shown in Table 1. The absorption edge of pure CdS is at about 565 nm, with the corresponding band gap of 2.2 eV, which is slightly smaller than the value of 2.4 eV reported previously [31]. The absorption capability in the visible light range of the Zn\({}_{0.15}\)Cd\({}_{0.85}\)S nanoflowers is enhanced as compared to pure CdS and there is an obvious absorption edge shift to 557 nm, which corresponds to a band gap of 2.23 eV, that may be due to the charge transfer between CdS valence band and Zn-3d doping level [32]. All of P25/Zn\({}_{0.15}\)Cd\({}_{0.85}\)S nanocomposite with various P25 contents could absorb light in visible light region, which may be due to the charge transfer between CdS and TiO\({}_{2}\) conduction bands [33]. XPS technique is used to investigate the chemical states of the pure CdS nanoparticles and P25/Zn\({}_{0.15}\)Cd\({}_{0.85}\)S nanocomposite (Figure 4). XPS survey spectrum of pure CdS indicates the presence of Cd 3d, S 2p, O 1s, and C 1s peaks, as shown in Figure 4a, while the survey scan of P25/Zn\({}_{0.15}\)Cd\({}_{0.85}\)S nanocomposite confirms the existence of Cd, S, O, C, as well as Ti and Zn elements. The Cd 3d core level spectra in Figure 4b indicate that there are two peaks in pure CdS nanoparticles and P25/Zn\({}_{0.15}\)Cd\({}_{0.85}\)S nanocomposite [34].