## 2 Results and Discussion
### Characterization of TiO\({}_{2}\), TC, and PPTC  
The SEM images of the as-prepared TiO\({}_{2}\), TC, and PPTC are shown in Figure 2. It can be seen that the as-prepared TiO\({}_{2}\) nanoparticles exhibit uneven sizes and tend to form aggregates (Figure 2A). The doping of Cu\({}^{2+}\) leads to some change in the fine structure of TiO\({}_{2}\) while the doped Cu\({}^{2+}\) tends to be gradually adhered onto the surface of TiO\({}_{2}\) matrix (Figure 2B). After TiO\({}_{2}\)/Cu nanocomposite is incorporated into the pores of PP via in-situ hydrothermal process, the resultant PPTC exhibits uniform nanoporous structure and the incorporated TiO\({}_{2}\)/Cu composite is free of aggregation (Figure 2C). Such a nanoporous structure of PPTC is favorable for increasing the contact area between the photocatalyst and organic pollutants, thereby improving the adsorption capacity and photocatalytic activity of the photocatalyst[8; 11; 14; 15]. Figure 1: Schematic diagram for preparing ketch porous polymers and PPTC. Figure 2: SEM images of (**A**) TiO\({}_{2}\), (**B**) TC, and (**C**) PPTC. Figure 3 displays typical TEM micrographs of TiO\({}_{2}\), TC, and PPTC. It is seen that TiO\({}_{2}\) has an irregular structure (Figure 3A). Cu nanoparticles with size of approximately 10 nm are doped into the structure of TiO\({}_{2}\) and prevented from aggregation in the as-formed TC composite (Figure 3B), and TC is embedded into the pores of PP to form PPTC while the structure of TiO\({}_{2}\) nanoparticle is kept nearly unchanged (Figure 3C). Moreover, the TC nanoparticles exhibit good dispersion in the as-prepared PPTC composite, which is because PP with a nanoporous structure can hinder their aggregation therein well. Figure 4 shows the XRD patterns of TiO\({}_{2}\), TC, and PPTC. The XRD peaks around 2\(\theta\) = 25.3\({}^{\circ}\), 38\({}^{\circ}\), 47.7\({}^{\circ}\), 54.8\({}^{\circ}\), 62.8\({}^{\circ}\), and 68.8\({}^{\circ}\) correspond to the (101), (004), (200), (105), (104), and (200) crystal faces of nano-TiO\({}_{2}\), respectively [5; 6; 7], and they prove that the as-prepared TiO\({}_{2}\) nanoparticle is of an anatase structure. The two peaks at about 43.5\({}^{\circ}\) and 50.6\({}^{\circ}\) possibly correspond to metallic Cu of TC [8; 18]. IN addition, doping Cu leads to little change in the crystal structure of TiO\({}_{2}\), and the TiO\({}_{2}\)/Cu composite embedded in the pores of PP via calcination of TBT and CuSO\({}_{4}\)5H\({}_{2}\)O in vacuum retains the initial state [16; 17], which could be beneficial for enhancing the contact area between TiO\({}_{2}\)/Cu composite and organic compound. Furthermore, we calculate the crystallization size of PPTC, TC, and TiO\({}_{2}\) from the XRD by using Scherrer formula and the sizes are 7.19 nm, 8.01 nm, and 7.22 nm, respectively. Thus, these results are almost equal to that of TEM. Moreover, the as-prepared PPTC do not obviously show the XRD signal of Cu, possibly because their content of doped Cu is too low, furthermore, that was covered by PP. Figure 5 illustrates the UV-vis absorbance spectra of TiO\({}_{2}\), TC, and PPTC. There are great differences in the optical absorbance behaviors of TiO\({}_{2}\), TC, and PPTC. On the one hand, the gradient decrease of  
Figure 4: XRD patterns of TiO\({}_{2}\), TC, and PPTC. Figure 3: TEM images of (**A**) TiO\({}_{2}\), (**B**) TC, and (**C**) PPTC. the reflectance at approximately 277 nm after the incorporation of Cu could be attributed to surface plasmon resonance that leads to enhanced photon capture at the visible region that is obviously stronger than TiO\({}_{2}\)[19]. On the other hand, TC has much stronger visible light absorbance than TiO\({}_{2}\) while PPTC shows broader photoresponse range as well as stronger visible light absorbance at about 425 nm as compared with TiO\({}_{2}\) and TC.