Spin-Polarized Photocatalytic CO₂ Reduction of Mn-Doped Perovskite Nanoplates

Abstract

"Spin" has been recently reported as an important degree of electronic freedom to improve the performance of electrocatalysts and photocatalysts. This work demonstrates the manipulations of spin-polarized electrons in CsPbBr₃ halide perovskite nanoplates (NPLs) to boost the photocatalytic CO₂ reduction reaction (CO₂RR) efficiencies by doping manganese cations (Mn²⁺) and applying an external magnetic field. Mn-doped CsPbBr₃ (Mn-CsPbBr₃) NPLs exhibit an outstanding photocatalytic CO₂RR compared to pristine CsPbBr₃ NPLs due to creating spin-polarized electrons after Mn doping. Notably, the photocatalytic CO₂RR of Mn-CsPbBr₃ NPLs is significantly enhanced by applying an external magnetic field. Mn-CsPbBr₃ NPLs exhibit 5.7 times improved performance of photocatalytic CO₂RR under a magnetic field of 300 mT with a permanent magnet compared to pristine CsPbBr₃ NPLs. The corresponding mechanism is systematically investigated by magnetic circular dichroism spectroscopy, ultrafast transient absorption spectroscopy, and density functional theory simulation. The origin of enhanced photocatalytic CO₂RR efficiencies of Mn-CsPbBr₃ NPLs is due to the increased number of spin-polarized photoexcited carriers by synergistic doping of the magnetic elements and applying a magnetic field, resulting in prolonged carrier lifetime and suppressed charge recombination. Our result shows that manipulating spin-polarized electrons in photocatalytic semiconductors provides an effective strategy to boost photocatalytic CO₂RR efficiencies.