Strong Spin Polarization Effect of Atomically Dispersed Metal Site Boosts the Selective Photocatalytic Nitrobenzene Hydrogenation to Aniline over Graphitic Carbon Nitride.

Atomically dispersed catalysts (ADCs) with a well-defined structure are theoretically desirable for a high-selectivity photocatalytic reaction. However, achieving high product selectivity remains a practical challenge for ADCs-based photocatalysts. Herein, we reveal a spin polarization effect on achieving high product selectivity (95.0%) toward the photocatalytic nitrobenzene (PhNO 2 ) hydrogenation to aniline (PhNH 2 ) on atomically dispersed Fe site-loaded graphitic carbon nitride (Fe/g-C 3 N 4 ). In combination with the Gibbs free energy diagram and electronic structure analysis, the origin of the photocatalytic performance is attributed not only to the strong metal-support interaction between the Fe site and g-C 3 N 4 , but more importantly to the strong spin polarization effect that promotes the potential-determining step (PDS) of *PhNO to *PhNOH. This work could be helpful for the design of ADCs-based photocatalysts in view of the spin polarization effect.