Electron Spin Polarization-Enhanced Photoinduced Charge Separation in Ferromagnetic ZnFe₂O₄

Investigating a high-efficiency photoelectrochemical (PEC) system is an essential strategy to realize solar energy conversion, and the catalytic activity is mostly regulated by the intrinsic electronic structure. Here, we synthesize a ferromagnetic ZnFe2O4 (ZFO) photoelectrode with an improved ferromagnetic property by introducing cation disorder and oxygen vacancies. Ferromagnetic ZnFe2O4 with an improved ferromagnetic property enables significant enhancement of PEC performance simply by placement of a permanent magnet to provide the photoelectrode with a magnetic field. The improvement is assigned to electron spin polarization of the ferromagnetic ZFO photoelectrode regulated by the magnetic field. Because of the spin state loss of excited electrons, there are many photoinduced electrons in the same spin state as holes, which is unfavorable for their recombination during the light excitation process. The polarization also benefits the charge transfer based on the magnetoresistance effect. This work extends the strategy of enhancing the separation of photoinduced charges.