Zeeman Effect-Boosted Spin-Polarized Band Splitting in Diluted Magnetic Photocatalysis Semiconductors for Efficient CO₂ Photoreduction

Magnetic field regulation is an effective strategy to improve the photocatalytic activity of magnetic semiconductor photocatalysts, but it is not suitable for widely used nonmagnetic photocatalytic semiconductors. Here, we report a Zeeman effect-driven spin-polarized band splitting phenomenon in diluted magnetic semiconductors that show efficient photocatalytic CO₂ reduction under visible-light irradiation. A flexible Ni²⁺-doped BaTiO₃ nanofiber film is used as the diluted magnetic semiconductor model to prove this concept. The interstitial Ni²⁺ dopant induces the spin-polarized bands in Ni-BaTiO₃ nanofibers to split under light excitation, generating spin-excited electrons and holes. This Zeeman effect induced by the magnetic field is more obvious since it intensifies the spin-polarized band splitting and generates more spin-excited electrons and holes, suppressing the carrier recombination and extending the carrier lifetime for CO₂ photoreduction. As a result, the evolution rates of CO and CH₄ are as high as 86.47 and 96.06 μmol/g/h under a small magnetic field of 50 mT. The proposed mechanism of Zeeman effect-driven spin-polarized band splitting is feasible to improve the CO₂ photoreduction efficiency of broadly applied diluted magnetic semiconductors.