Fabrication of magnetic Fe3O4@SiO2@Bi2O2CO3/rGO composite for enhancing its photocatalytic performance for organic dyes and recyclability.

A novel magnetic Fe3O4@SiO2@Bi2O2CO3/rGO composite comprising of uniform core-shell-structured Fe3O4@SiO2@Bi2O2CO3 microspheres mounted on reduced graphene oxide (rGO) sheets was successfully fabricated by using a facile hydrothermal method. The adsorption-desorption isotherm of Fe3O4@SiO2@Bi2O2CO3/rGO belonged to type IV with an H4-type hysteresis loop. The specific surface areas and magnetization saturation value (Ms) of Fe3O4@SiO2@Bi2O2CO3/rGO (x = 0.15 g) were 102.12 m2/g and 25.4 emu/g, respectively. Fe3O4@SiO2@Bi2O2CO3/rGO (x = 0.15 g) exhibited remarkable photocatalytic degradation activity and mineralization effect for MO and decolorization performance for the mixed solution of MO, Rh B, and MB. MO degradation by Fe3O4@SiO2@Bi2O2CO3/rGO conformed to a first-order kinetic reaction, and the corresponding kapp value was 0.05553 min-1. A suitable amount of rGO in Fe3O4@SiO2@Bi2O2CO3/rGO could decrease the energy band gap, inhibit the recombination of photo-induced electron/hole (e-/h+) pair, and broaden and enhance the response of the catalyst to visible light, thereby enhancing the visible-light catalytic degradation of organic dyes. The active species produced in the photocatalysis included •O2-, •OH, and h+, with •O2- being the dominant active species. The as-prepared photocatalyst also showed excellent magnetic separation performance and stability. Results show that the as-prepared Fe3O4@SiO2@Bi2O2CO3/rGO composite is a promising photocatalyst with considerable application potential in organic dyes removal.