Spin Polarization-Boosting Ultrafast Carrier Dynamics and Exciton Dissociation in Fe Nanoparticle-Loading Graphitic Carbon Nitride toward Efficient CO2 Photoreduction

Abstract

The regulation of exciton properties plays a crucial role in enhancing the activity of photocatalysts, primarily due to the rapid recombination of photoinduced electron–hole pairs caused by the strong Coulomb interaction between them. In this study, we explore the spin polarization effect in nanohybrids composed of graphitic carbon nitride (g-C3N4) and iron (Fe) nanoparticles, which accelerates exciton dissociation and spin-selective electron transfer, thereby improving the selective photoreduction of CO2 into CO. Mechanistic studies reveal that the Fe2+/Fe3+ redox pairs, embedded in the iron oxide layer on the surface of Fe nanoparticles, function as ultrafast charge transfer shuttles via a double exchange interaction (Fe2+–O–Fe3+). This process facilitates spin-selective electron transfer from g-C3N4 to Fe species, thereby contributing to the efficient conversion of CO2. This work provides novel insights into the design of spin-dependent photocatalysts for efficient solar energy conversion.