Synchronous Regulation of Ferroelectric and Spin Polarization for High-Efficiency Photocatalytic Water Splitting

Enhancing the ferroelectric polarization field and tuning the electron spin polarization as novel approaches to improve photocatalytic performance have sparked considerable research interest. Obviously, a straightforward strategy to simultaneously regulate ferroelectric and spin polarization will have a very attractive application prospect. In this study, a series of Bi₄NbO₈Cl-Ni photocatalysts are synthesized by doping different concentrations of magnetic element Ni into ferroelectric semiconductor Bi₄NbO₈Cl. Due to the significant difference in atomic radius, Ni doping induces greater structural distortion and enhances the deviation of positive and negative charge centers in the crystal, thereby resulting in a stronger ferroelectric polarization field. Moreover, spin polarization is induced in the electrons, and photogenerated carriers exhibit higher spatial separation efficiency under magnetic field. Thanks to the synchronous regulation of ferroelectric and spin polarization by Ni doping, the average rates of H₂ and O₂ production from photocatalytic water splitting over Bi₄NbO₈Cl-Ni under visible light are 342.6 and 207.1 µmol g^-1 h^-1, respectively, which are 10.6 and 2.7 times those of pure Bi₄NbO₈Cl. Notably, under an applied magnetic field of 300 mT, the average production rates are further promoted up to 616.7 and 331.4 µmol g^-1 h^-1. This study offers a novel strategy to significantly improve photocatalytic performance.