Influence of semiconductor/insulator/semiconductor structure on the photo-catalytic activity of Fe3O4/SiO2/polythiophene core/shell submicron composite

• Fe3O4/SiO2/polythiophene (FSP) with a SIS structure was obtained.
• The rate constant is 2.5 times higher than that of TiO2 due to its SIS structure.
• The energy band change of SIS structure and the effective radicals were studied.
• Their photochemical stability and magnetic recovery are beneficial for application.

The Fe3O4/SiO2/polythiophene (FSP) submicron composite (SC) with a structure of semiconductor/insulator/semiconductor (SIS) was obtained. The characterization results showed that the FSP SC had a spherical core/shell shape with an average diameter of 506 nm. The high saturated magnetization value (∼39 emu/g) ensured the easy separation of FSP SC from aqueous solution. The photo-catalytic activity of the FSP SC was evaluated by the degradation of methyl orange (MO) under UV-irradiation in the presence of H2O2. Due to the SIS structure, the degradation rate constant by FSP SC (0.02177 min−1) was 6.4, 1.6, and 2.5 times higher than that of Fe3O4/polythiophene (FP), polythiophene (P), and TiO2, respectively. The repetition results suggested the good photochemical stability of FSP SC. The mechanism was proposed by investigating the energy band variation of the SIS structure, the transfer of light generated carriers and the formation of effective hydroxyl radicals in the photo-catalysis progress.

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