## 3 Results and Discussion  
The XRD patterns of Fe\({}_{3}\)O\({}_{4}\), TiO\({}_{2}\), Fe\({}_{3}\)O\({}_{4}\)@SiO\({}_{2}\), and FS-FT (0 g) are displayed in Figure 1a. The diffraction peak position of TiO\({}_{2}\) on the outer layer of FS-FT (0 g) is the same as that of TiO\({}_{2}\). According to JCPDS 65-3369, the peaks of FS-FT (0 g) are observed at 25.2\({}^{\circ}\), 38.7\({}^{\circ}\), 48\({}^{\circ}\), 54\({}^{\circ}\), and 55.14\({}^{\circ}\), which are attributed to the (101), (004), (200), (105), (211), and (204) crystal planes of TiO\({}_{2}\), respectively. The findings reveal that TiO\({}_{2}\) displays an anatase structure [17]. According to JCPDS 02-0387, the peaks of Fe\({}_{3}\)O\({}_{4}\) are observed at 30.1\({}^{\circ}\), 35.5\({}^{\circ}\), 43.1\({}^{\circ}\), 53.4\({}^{\circ}\), 56.9\({}^{\circ}\), and 62.5\({}^{\circ}\). These peaks are attributed to the (220), (311), (400), (422), (511), and (440) planes of the magnetite phase, respectively [18]. The XRD pattern of Fe\({}_{3}\)O\({}_{4}\)@SiO\({}_{2}\) exhibits diffraction peaks identical to those of Fe\({}_{3}\)O\({}_{4}\). In Figure 1a, the peak absorption of Fe\({}_{3}\)O\({}_{4}\) in FS-FT (0 g) and Fe\({}_{3}\)O\({}_{4}\)@SiO\({}_{2}\) is lower than that of Fe\({}_{3}\)O\({}_{4}\), due to Fe\({}_{3}\)O\({}_{4}\) being coated in the inner layer of FS-FT (0 g) and Fe\({}_{3}\)O\({}_{4}\)@SiO\({}_{2}\). Figure 1b shows the XRD patterns of FS-FT (0.18-0.45 g). The peaks of TiO\({}_{2}\) appear at 25.3\({}^{\circ}\), 39.2\({}^{\circ}\), 48.5\({}^{\circ}\), and 55.3\({}^{\circ}\), which relate to the (101), (004), (200), and (211) crystal planes, respectively (JCPDS No. 65-3369). In comparison with the peak intensity and the FWHM of FS-FT (0 g), the intensity of FS-FT (0.18-0.45 g) decreases and the FWHM increases; especially at 25.3\({}^{\circ}\), the change is very obvious. The characteristic peaks of the XRD represent the number of crystal faces aligned along the same direction, and Fe atoms enter into the lattice arrangement of TiO\({}_{2}\). The substitution of part of Ti\({}^{4+}\) by Fe\({}^{3+}\) caused a change in the crystal morphology and resulted in a reduction in the number of crystal planes [19]. It is also apparent that the peaks of TiO\({}_{2}\) (101) move to the right; the observed structural modification originates from the ionic radius discrepancy between Fe\({}^{3+}\) (0.055 nm) and Ti\({}^{4+}\) (0.061 nm), where smaller Fe\({}^{3+}\) ions induce lattice contraction through substitutional doping in the TiO\({}_{2}\) matrix [19]. The substitution of Fe\({}^{3+}\) ions introduces defect states within the bandgap of TiO\({}_{2}\), thus affecting the peak intensity. The characteristic diffraction peaks of the (311), (440), and (533)crystal planes of Fe\({}_{5}\)O\({}_{4}\) in the core of Fe\({}_{5}\)O\({}_{4}\)@SiO\({}_{2}\)@Fe-TiO\({}_{2}\) appear, thus indicating that Fe\({}_{5}\)O\({}_{4}\)@SiO\({}_{2}\)@Fe-TiO\({}_{2}\) can provide magnetic solid responsiveness for subsequent cycling experiments [20]. The TEM of FS-FT (0 g) and FS-FT (0.36 g) are shown in Figure 2a,b. It is evident that the samples exhibit a distinct core-shell morphology. As illustrated in Figure 2c, the HRTEM image of FS-FT (0 g) reveals the interplanar distance of 0.355 nm, attributable to the (101) plane of TiO\({}_{2}\), and the distance between the crystal planes is 0.176 nm, related to the (422) plane of Fe\({}_{5}\)O\({}_{4}\)[21]. Figure 2d shows the HRTEM image of FS-FT (0.36 g), where the crystal plane distance is 0.354 nm. It can be attributed to the (101) plane of TiO\({}_{2}\), and 0.253 nm can be attributed to the (311) plane of Fe\({}_{5}\)O\({}_{4}\). The interplanar distance of the (101) plane of TiO\({}_{2}\) in FS-FT (0.36 g) is slightly smaller than that in FS-FT (0 g); the reason for this may be that the scale of Fe\({}^{3+}\) in the lattice arrangement is more minor than that of Ti\({}^{4+}\), or it may be caused by a measurement error.