Spin polarization in Fe-doped CsPbBr₃ perovskite nanocrystals for enhancing photocatalytic CO₂ reduction

Spin manipulation offers an effective strategy to enhance photocatalytic activity in metal halide perovskites by suppressing the recombination of photo-excited electrons. However, the scope of the magnetic dopant inducing spin polarization is still limited. Here, we introduce synergetic strategies to polarize the spin in photo-excited electrons and boost their photocatalytic activity for CO₂ reduction. We dope iron cation (Fe²⁺) into CsPbBr₃ perovskite nanocrystals (PNCs). Fe ions induce paramagnetism, fostering spin polarization within the Fe-doped CsPbBr₃ PNCs (Fe-CsPbBr₃ PNCs) under magnetic fields. The magnetic compositions in PNC tend to stabilize the spin polarized electrons within the PNC, mitigate the recombination of photo-excited electrons and enhance the redox reaction for photocatalytic CO₂ reduction. The synergistic effects of magnetic element doping and the application of magnetic fields resulted in a photocatalytic CO₂ reduction of 133.04 μmol g⁻¹, which is 1.68-fold increase compared to the Fe-PNC without a magnetic field. This work provides a simple and environmentally friendly approach to CO₂ reduction based on PNCs.