A Spin-Polarized Electron-Induced MXene-KBi0.9Co0.1Fe2O5 Photocatalyst for Enhanced Dye Degradation

In photocatalysts aimed to degrade environmental pollutants, photons are generally used as primary stimuli to generate electron–hole pairs to target the chemical bonds to disintegrate. Recently, electron spin has been reported as an essential degree of freedom to improve the performance of photocatalysts. In this work, spin-polarized electrons and holes are introduced into a brownmillerite KBi_0.9Co_0.1Fe₂O₅ semiconductor and a two-dimensional (2D) MXene composite system by application of an external magnetic field. The spin polarization properties are monitored by measuring the magnetoresistance effect of the MXene-KBCFO device, which is related to the carrier transfer efficiency. Remarkably, the photocatalytic performance of MXene-KBCFO is significantly enhanced by the simultaneous application of an external magnetic field and illumination due to the increased number of spin-polarized photoexcited carriers caused by the synergy effect of the 2D MXene heterostructure together with the ferromagnetic spin ordering. This results in increased reaction hotspots, effective built-in electric field, extended carrier lifetime, and reduced charge recombination owing to parallel alignment of electron spin orientation. The results show that the efficiency and stability of photocatalytic dye degradation can be effectively enhanced by manipulating the spin-polarized electrons in the MXene-based oxide-perovskite heterostructure photocatalyst.