Modulating negative magnetoresistance via inducing vacancy for regulates electron transport under magnetic ambient conditions

The introduction of external magnetic field is one of the most widely studied strategies for photogenerated carrier separation in recent years. However, magnetic materials have great disadvantages in terms of photocatalytic performance. Semiconductor materials with magnetic properties are also extremely rare. It is extremely peculiar to research the magnetism of semiconductor photocatalyst triggered by vacancy. Here, the first example of ferromagnetic Bi₂S₃ is achieved by controlled Bi vacancy (Bi₂S₃-V_Bi). The magnetism properties depends largely on the spin polarization of p electrons in S atoms, and its magnetic moment is mainly distributed on S atoms around cation vacancies. Under the induction of external magnetic field, the tunneling of spin-polarized electrons in S-2p orbital makes Bi₂S₃-V_Bi have negative magnetoresistance effect. The ferromagnetic arrangement of Bi₂S₃-V_Bi particles can reduce the resistivity and increase the tunneling of electrons. Meanwhile, Lorentz force generated by external magnetic field acts reversely on photogenerated electrons and holes, thus effectively inhibiting the recombination of carriers in photocatalyst. Moreover, the influence of Bi vacancy on Bi₂S₃ magnetism is investigated by DFT calculation. This study provides a new strategy for effective carrier separation in photocatalysis.