The N2 adsorption–desorption isotherm can be categorized as type IV curve, with a distinct hysteresis loop observed in the range of 0.45–1.0 P/P0[28]. The average pore diameter was 2.5 nm. The BET area and total pore volume were calculated to be 321 m2/g and 0.29 cm3/g, respectively. The small angle X-ray diffraction pattern (SAXRD) of the SH-mSi@Fe3O4 (Fig. S1 of supplementary information) shows only one peak at 2θ degree of 2.55, indicating the wormhole-like pore structure within the prepared mesoporous framework, rather than long-range mesopore channels [29]. This is probably due to the cross-linked organic group being homogeneously distributed in the silica matrix, which results in less condensed organic-silica framework [30], [31] and [32]. Fourier infrared spectrum (Fig. 2) shows the characteristic peaks of the SH-mSi@Fe3O4 at 890 cm−1 (Si–C), 1090 cm−1 (Si–O stretch of Si–O–Me), 2825 cm−1(C–H stretches of O–CH3), and 2935 cm−1 (normal C–H stretch of propyl). The double peaks of S–H were found at 2358 and 2345 cm−1, which are typically very weak due to the aggregation of mercapto groups within the monolayer and hydrogen binding effects. The absorption bands at 586 and 636 cm−1 are usually attributed to the Fe–O stretches[27] and [33].Both SEM and TEM images (Fig. 3) illustrate the spherical morphology of SH-mSi@Fe3O4. The average diameter of the particles is around 500 nm. It is observed from Fig. 3b that the skirt of the particles is lighter than the central part, indicating the less compact outer mesoporous shell and the condensed inner magnetic cores. Element mass contents of Si, S and Fe (Fig. S2 of supplementary information) in SH-mSi@Fe3O4 were 17.95%, 1.23% and 38.03%, respectively.